This document presents an approach for online monitoring of voltage stability margin in power systems using synchrophasor measurements from phasor measurement units (PMUs). The approach fits quadratic curves to the P-V and Q-V curves of each load bus using three sets of PMU measurements and pseudo-measurements. It determines the real and reactive power loading margins of each bus, and takes the minimum of these across all buses as the system's overall loading margins. It also identifies the most critical bus based on these margins. The approach updates the loading margins and critical bus identification regularly as system conditions change using new PMU measurements. Case studies on IEEE test systems and a large Indian power grid validate the effectiveness of the proposed online monitoring approach.
This document discusses using a Unified Power Flow Controller (UPFC) to improve the performance and reliability of a transmission line in Rajkot, India. It first reviews Flexible AC Transmission Systems (FACTS) and the UPFC. It then describes a transmission network model of Rajkot created in MATLAB based on real system data. Various hypothetical future load conditions are simulated both with and without a UPFC to study how it can help control power flow in the network more efficiently. Results show the UPFC improves utilization of the existing infrastructure by allowing more optimal power flow.
This document proposes an artificial neural network and fuzzy logic controller tool for online voltage stability monitoring and estimating reactive power (VAR) support needs in deregulated power systems. The tool uses bus voltage angles and reactive power loads as inputs to the ANN, which then outputs the voltage stability margin and voltage stability factor of the most vulnerable bus. The ANN is trained offline using patterns from continuation power flow simulations. The tool can estimate stability margins and determine minimum VAR support for different system conditions and contingencies in deregulated markets. It has been tested on IEEE 14 bus and 30 bus systems.
This document discusses a proposed tool using support vector regression (SVR) and fuzzy logic controller (FLC) for online voltage stability monitoring and estimation of reactive power (VAR) support in deregulated power systems. The tool uses bus voltage angle and reactive power load as inputs to SVR to predict the voltage stability margin index (VSMI) and voltage stability factor (VSF) of the most critical bus. The results of SVR are compared to artificial neural networks in terms of accuracy and computation time on IEEE 14 bus and 30 bus test systems. The tool estimates voltage stability margins for different transactions and contingencies and determines the minimum VAR support needed to enhance stability.
Series of blackouts encountered in recent years in power system have been occurred because either of voltage or angle instability or both together was not detected within time and progressive voltage or angle instability further degraded the system condition, because of increase in loading. This paper presents the real-time assessment methodology of voltage stability using Phasor Measurement Unit (PMU) with observability of load buses only in power network. PMUs are placed at strategically obtained location such that minimum number of PMU’s can make all load buses observable. Data obtained by PMU’s are used for voltage stability assessment with the help of successive change in the angle of bus voltage with respect to incremental load, which is used as on-line voltage stability predictor (VSP). The real-time voltage phasors obtained by PMU’s are used as real time voltage stability indicator. The case study has been carried out on IEEE-14 bus system and IEEE-30 bus systems to demonstrate the results.
This paper presents a real-time emulator of a dual permanent magnet synchronous motor (PMSM) drive implemented on a field-programmable gate array (FPGA) board for supervision and observation purposes. In order to increase the reliability of the drive, a sensorless speed control method is proposed. This method allows replacing the physical sensor while guaranteeing a satisfactory operation even in faulty conditions. The novelty of the proposed approach consists of an FPGA implementation of an emulator to control the actual system. Hence, this emulator operates in real-time with actual system control in healthy or faulty mode. It gives an observation of the speed rotation in case of fault for the sake of continuity of service. The observation of the rotor position and the speed are achieved using the dSPACE DS52030D digital platform with a digital signal processor (DSP) associated with a Xilinx FPGA.
The inverter is the principal part of the photovoltaic (PV) systems that assures the direct current/alternating current (DC/AC) conversion (PV array is connected directly to an inverter that converts the DC energy produced by the PV array into AC energy that is directly connected to the electric utility). In this paper, we present a simple method for detecting faults that occurred during the operation of the inverter. These types of faults or faults affect the efficiency and cost-effectiveness of the photovoltaic system, especially the inverter, which is the main component responsible for the conversion. Hence, we have shown first the faults obtained in the case of the short circuit. Second, the open circuit failure is studied. The results demonstrate the efficacy of the proposed method. Good monitoring and detection of faults in the inverter can increase the system's reliability and decrease the undesirable faults that appeared in the PV system. The system behavior is tested under variable parameters and conditions using MATLAB/Simulink.
Optimal Placement of DG for Loss Reduction and Voltage Sag Mitigation in Radi...IDES Editor
This paper presents the need to operate the power
system economically and with optimum levels of voltages has
further led to an increase in interest in Distributed
Generation. In order to reduce the power losses and to improve
the voltage in the distribution system, distributed generators
(DGs) are connected to load bus. To reduce the total power
losses in the system, the most important process is to identify
the proper location for fixing and sizing of DGs. It presents a
new methodology using a new population based meta heuristic
approach namely Artificial Bee Colony algorithm(ABC) for
the placement of Distributed Generators(DG) in the radial
distribution systems to reduce the real power losses and to
improve the voltage profile, voltage sag mitigation. The power
loss reduction is important factor for utility companies because
it is directly proportional to the company benefits in a
competitive electricity market, while reaching the better power
quality standards is too important as it has vital effect on
customer orientation. In this paper an ABC algorithm is
developed to gain these goals all together. In order to evaluate
sag mitigation capability of the proposed algorithm, voltage
in voltage sensitive buses is investigated. An existing 20KV
network has been chosen as test network and results are
compared with the proposed method in the radial distribution
system.
Improved predictive current model control based on adaptive PR controller for...IJECEIAES
This paper investigates an improved current predictive model control (PCMC) strategy with a prediction horizon of one sampling time for voltage regulation in standalone system based on diesel engine driven fixed speed synchronous generator. An adaptive PR controller with anti-windup scheme is employed to achieve high performance regulation without saturation issues. In addition, new method to obtain the optimal parameters of the adaptive PR controller to achieve high performance during the transition and in steady state, is provided. Furthermore, to balance the power at the point of common coupling (PCC), as well as, to fulfilling a clean power to the connected loads, a three-phase voltage source inverter (VSI) with LRC filter is controlled using the developed improved PCMC strategy. The output filter current is controlled using the predicting of the system behaviour model in the future step, at each sampling prediction time. The performances of the developed control strategy are verified using Matlab/Simulink interface.
This document discusses using a Unified Power Flow Controller (UPFC) to improve the performance and reliability of a transmission line in Rajkot, India. It first reviews Flexible AC Transmission Systems (FACTS) and the UPFC. It then describes a transmission network model of Rajkot created in MATLAB based on real system data. Various hypothetical future load conditions are simulated both with and without a UPFC to study how it can help control power flow in the network more efficiently. Results show the UPFC improves utilization of the existing infrastructure by allowing more optimal power flow.
This document proposes an artificial neural network and fuzzy logic controller tool for online voltage stability monitoring and estimating reactive power (VAR) support needs in deregulated power systems. The tool uses bus voltage angles and reactive power loads as inputs to the ANN, which then outputs the voltage stability margin and voltage stability factor of the most vulnerable bus. The ANN is trained offline using patterns from continuation power flow simulations. The tool can estimate stability margins and determine minimum VAR support for different system conditions and contingencies in deregulated markets. It has been tested on IEEE 14 bus and 30 bus systems.
This document discusses a proposed tool using support vector regression (SVR) and fuzzy logic controller (FLC) for online voltage stability monitoring and estimation of reactive power (VAR) support in deregulated power systems. The tool uses bus voltage angle and reactive power load as inputs to SVR to predict the voltage stability margin index (VSMI) and voltage stability factor (VSF) of the most critical bus. The results of SVR are compared to artificial neural networks in terms of accuracy and computation time on IEEE 14 bus and 30 bus test systems. The tool estimates voltage stability margins for different transactions and contingencies and determines the minimum VAR support needed to enhance stability.
Series of blackouts encountered in recent years in power system have been occurred because either of voltage or angle instability or both together was not detected within time and progressive voltage or angle instability further degraded the system condition, because of increase in loading. This paper presents the real-time assessment methodology of voltage stability using Phasor Measurement Unit (PMU) with observability of load buses only in power network. PMUs are placed at strategically obtained location such that minimum number of PMU’s can make all load buses observable. Data obtained by PMU’s are used for voltage stability assessment with the help of successive change in the angle of bus voltage with respect to incremental load, which is used as on-line voltage stability predictor (VSP). The real-time voltage phasors obtained by PMU’s are used as real time voltage stability indicator. The case study has been carried out on IEEE-14 bus system and IEEE-30 bus systems to demonstrate the results.
This paper presents a real-time emulator of a dual permanent magnet synchronous motor (PMSM) drive implemented on a field-programmable gate array (FPGA) board for supervision and observation purposes. In order to increase the reliability of the drive, a sensorless speed control method is proposed. This method allows replacing the physical sensor while guaranteeing a satisfactory operation even in faulty conditions. The novelty of the proposed approach consists of an FPGA implementation of an emulator to control the actual system. Hence, this emulator operates in real-time with actual system control in healthy or faulty mode. It gives an observation of the speed rotation in case of fault for the sake of continuity of service. The observation of the rotor position and the speed are achieved using the dSPACE DS52030D digital platform with a digital signal processor (DSP) associated with a Xilinx FPGA.
The inverter is the principal part of the photovoltaic (PV) systems that assures the direct current/alternating current (DC/AC) conversion (PV array is connected directly to an inverter that converts the DC energy produced by the PV array into AC energy that is directly connected to the electric utility). In this paper, we present a simple method for detecting faults that occurred during the operation of the inverter. These types of faults or faults affect the efficiency and cost-effectiveness of the photovoltaic system, especially the inverter, which is the main component responsible for the conversion. Hence, we have shown first the faults obtained in the case of the short circuit. Second, the open circuit failure is studied. The results demonstrate the efficacy of the proposed method. Good monitoring and detection of faults in the inverter can increase the system's reliability and decrease the undesirable faults that appeared in the PV system. The system behavior is tested under variable parameters and conditions using MATLAB/Simulink.
Optimal Placement of DG for Loss Reduction and Voltage Sag Mitigation in Radi...IDES Editor
This paper presents the need to operate the power
system economically and with optimum levels of voltages has
further led to an increase in interest in Distributed
Generation. In order to reduce the power losses and to improve
the voltage in the distribution system, distributed generators
(DGs) are connected to load bus. To reduce the total power
losses in the system, the most important process is to identify
the proper location for fixing and sizing of DGs. It presents a
new methodology using a new population based meta heuristic
approach namely Artificial Bee Colony algorithm(ABC) for
the placement of Distributed Generators(DG) in the radial
distribution systems to reduce the real power losses and to
improve the voltage profile, voltage sag mitigation. The power
loss reduction is important factor for utility companies because
it is directly proportional to the company benefits in a
competitive electricity market, while reaching the better power
quality standards is too important as it has vital effect on
customer orientation. In this paper an ABC algorithm is
developed to gain these goals all together. In order to evaluate
sag mitigation capability of the proposed algorithm, voltage
in voltage sensitive buses is investigated. An existing 20KV
network has been chosen as test network and results are
compared with the proposed method in the radial distribution
system.
Improved predictive current model control based on adaptive PR controller for...IJECEIAES
This paper investigates an improved current predictive model control (PCMC) strategy with a prediction horizon of one sampling time for voltage regulation in standalone system based on diesel engine driven fixed speed synchronous generator. An adaptive PR controller with anti-windup scheme is employed to achieve high performance regulation without saturation issues. In addition, new method to obtain the optimal parameters of the adaptive PR controller to achieve high performance during the transition and in steady state, is provided. Furthermore, to balance the power at the point of common coupling (PCC), as well as, to fulfilling a clean power to the connected loads, a three-phase voltage source inverter (VSI) with LRC filter is controlled using the developed improved PCMC strategy. The output filter current is controlled using the predicting of the system behaviour model in the future step, at each sampling prediction time. The performances of the developed control strategy are verified using Matlab/Simulink interface.
Transmission lines react to an unexpected increase in power, and if these power changes are not controlled, some lines will become overloaded on certain routes. Flexible alternating current transmission system (FACTS) devices can change the voltage range and phase angle and thus control the power flow. This paper presents suitable mathematical modeling of FACTS
devices including static var compensator (SVC) as a parallel compensator and high voltage direct current (HVDC) bonding. A comprehensive modeling of SVC and HVDC bonding in the form of simultaneous applications for power flow is also performed, and the effects of compensations are compared. The comprehensive model obtained was implemented on the 5-bus test system in MATLAB software using the Newton-Raphson method, revealed that generators have to produce more power. Also, the addition of these devices stabilizes the voltage and controls active and reactive power in the network.
Direct current (DC) electronic load is a useful equipment for testing the electrical system. It can emulate various load at a high rating. The electronic load requires a power converter to operate and a linear regulator is a common option. Nonetheless, it is hard to control due to the temperature variation. This paper proposed a DC electronic load using the boost converter. The proposed electronic load operates in the continuous current mode and control using the integral controller. The electronic load using the boost converter is compared with the electronic load using the linear regulator. The results show that the boost converter able to operate as an electronic load with an error lower than 0.5% and response time lower than 13 ms.
The hardware implementation of sensorless brushless direct current motor drive incorporating H-infinity control strategy with optimized weights by particle swarm optimization in the speed control is carried out in this work. The methodology involved in the design of brushless direct current (BLDC) motor control with sensorless position detection technique, the design of H-infinity speed controller, steps involved in particle swarm optimization for optimizing coefficients of its weights and the hardware implementation is discussed in detail in this paper. Texas Instruments microcontroller board C2000 Delfino Launchpad LAUNCHXL F28377S and driver BOOSTXL DRV8301 are used for realization of the speed controller. The code is developed using C2000 hardware support package in MATLAB/SIMULINK platform. A comprehensive performance analysis is accomplished during starting of the motor and during the fast application and removal of load. This strategy is found to be robust resulting in faster load disturbance rejection and better reference speed tracking. The experimental results of the proposed strategy are compared with that of conventional proportional-integral (PI) controller. The time domain parameters are also compared. It is found that the proposed strategy exhibits better performance characteristics during transients and sudden disturbances in load.
An inverter system applied with the PV source typically has a problem of lower input voltage due to constraint in the PV strings connection. As a countermeasure a DC-DC boost converter is placed in between to achieve a higher voltage at the inverter DC link for connection to the grid and to realize the MPPT operation. This additional stage contributes to losses and complexity in control thus reducing the overall system efficiency. This work discussed on the design and development of a grid-connected quasi-Z-source PV inverter which has different topology and control method compared to the conventional voltage source inverter and able to overcome the above disadvantages. Modelling and performance analysis of the voltage and current controller to achieve a good power transfer from the PV source, as well sycnchronization with the grid are presented in detail. Results from both simulation and experimental verification demonstrate the designed and developed grid-connected qZSI PV inverter works successfully equivalent to the conventional voltage source inverter system.
Impact of hybrid FACTS devices on the stability of the Kenyan power system IJECEIAES
Flexible alternating current transmission system (FACTS) devices are deployed for improving power system’s stability either singly or as a combination. This research investigates hybrid FACTS devices and studies their impact on voltage, small-signal and transient stability simultaneously under various system disturbances. The simulations were done using five FACTS devices-static var compensator (SVC), static synchronous compensator (STATCOM), static synchronous series compensators (SSSC), thyristor controlled series compensator (TCSC) and unified power flow controller (UPFC) in MATLAB’s power system analysis toolbox (PSAT). These five devices were grouped into ten pairs and tested on Kenya’s transmission network under specific contingencies: the loss of a major generating machine and/or transmission line. The UPFC-STATCOM pair performed the best in all the three aspects under study. The settling times were 3 seconds and 3.05 seconds respectively for voltage and rotor angle improvement on the loss of a major generator at normal operation. The same pair gave settling times of 2.11 seconds and 3.12 seconds for voltage and rotor angle stability improvement respectively on the loss of a major transmission line at 140% system loading. From the study, two novel techniques were developed: A performance-based ranking system and classification for FACTS devices.
The emerging of inductive wireless power transfer (IWPT) technology provides more opportunities for the electric vehicle (EV) battery to have a better recharging process. With the development of IWPT technology, various way of wireless charging of the EV battery is proposed in order to find the best solution. To further understand the fundamentals of the IWPT system itself, an ample review is done. There are different ways of EV charging which are static charging (wired), static wireless charging (SWC) and dynamic wireless charging (DWC). The review starts with a brief comparison of static charging, SWC and DWC. Then, in detailed discussion on the fundamental concepts, related laws and equations that govern the IWPT principle are also included. In this review, the focus is more on the DWC with a little discussion on static charging and SWC to ensure in-depth understanding before one can do further research about the EV charging process. The in-depth perception regarding the development of DWC is elaborated together with the system architecture of the IWPT and DWC system and the different track versions of DWC, which is installable to the road lane.
Mainly the DC motors are employed in most of the application. The main objective is to Regulate the DC motor system. A motor which displays the appearances of a DC motor but there is no commutator and brushes is called as brushless DC motor. These motors are widespread to their compensations than other motors in relationships of dependability, sound, efficiency, preliminary torque and longevity. To achieve the operation more reliable and less noisy, brushless dc motors are employed. In the proposed work, dissimilar methods of speed control are analysed. In real time submission of speed control of BLDC motor, numerous strategies are executed for the speed control singularity. The modified approaches are the employment of PI controller, use of PID controller and proposed current controller.
Design and Experimental Results of Universal Electric Vehicle Charger Using DSPTELKOMNIKA JOURNAL
Owing to the growing concerns over energy depletion and environmental issues around the
world, more and more attention is given on replacing the fuel -based automobiles with electric vehicles
(EVs) which have the characteristics of zero-emission and low noise. As a result, various countries have
taken specific initiatives to de-carbonize their transport sectors by developing their own EV industry.
Regardless of the environmental and economic benefits, substantial scales of grid-connected EVs impose
incredible difficulties to the power grid. The main issues caused by EV charging to the power grid include
harmonics, voltage drop, system instability, system losses and grid overloading. Therefore, this paper
presents design and development of a novel method, which is by applying voltage-oriented control (VOC)
algorithm in battery charging of electric bus.The power system of this work consists of three-phase PWM
rectifier. The proposed method is based on mathematical analysis. Simulation and experimental works are
performed to investigate behavior and performance of the proposed algorithm. This paperclearly described
implementation of low and medium power laboratory prototype and operation of digital signal processor
(DSP) via MATLAB / Simulink for the proposed method.
Design and Performance Analysis of Genetic based PID-PSS with SVC in a Multi-...IDES Editor
Damping of power system oscillations with the help
of proposed optimal Proportional Integral Derivative Power
System Stabilizer (PID-PSS) and Static Var Compensator
(SVC)-based controllers are thoroughly investigated in this
paper. This study presents robust tuning of PID-PSS and
SVC-based controllers using Genetic Algorithms (GA) in
multi machine power systems by considering detailed model
of the generators (model 1.1). The effectiveness of FACTSbased
controllers in general and SVC-based controller in
particular depends upon their proper location. Modal
controllability and observability are used to locate SVC–based
controller. The performance of the proposed controllers is
compared with conventional lead-lag power system stabilizer
(CPSS) and demonstrated on 10 machines, 39 bus New England
test system. Simulation studies show that the proposed genetic
based PID-PSS with SVC based controller provides better
performance.
Alternating current (AC) electrical drives mainly require smaller current (or torque) ripples and lower total harmonic distortion (THD) of voltage for excellent drive performances. Normally, in practice, to achieve these requirements, the inverter needs to be operated at high switching frequency. By operating at high switching frequency, the size of filter can be reduced. However, the inverter which oftenly employs insulated gate bipolar transistor (IGBT) for high power applications cannot be operated at high switching frequency. This is because, the IGBT switching frequency cannot be operated above 50 kHz due to its thermal restrictions. This paper proposes an alternate switching strategy to enable the use of IGBT for operating the inverter at high switching frequency to improve THD performances. In this strategy, each IGBT in a group of switches in the modified inverter circuit will operate the switching frequency at one-fourth of the inverter switching frequency. The alternate switching is implemented using simple analog and digital integrated circuits.
The growing demand for electricity and the increasing integration of clean energies into the electrical grids requires the multiplication and reinforcement of high-voltage direct current (HVDC) projects throughout the world and demonstrates the interest in this electricity transmission technology. The transmitting system of the voltage source converter-high-voltage direct current (VSC-HVDC) consists primarily of two converter stations that are connected by a dc cable. In this paper, a nonlinear control based on the backstepping approach is proposed to improve the dynamic performance of a VSC-HVDC transmission system, these transport systems are characterized by different complexities such as parametric uncertainties, coupled state variables, neglected dynamics, presents a very interesting research topic. Our contribution through adaptive control based on the backstepping approach allows regulating the direct current (DC) bus voltage and the active and reactive powers of the converter stations. Finally, the validity of the proposed control has been verified under various operating conditions by simulation in the MATLAB/Simulink environment.
Recently, LCL has become amongst the most attractive filter used for grid-connected flyback inverters. Nonetheless, the switching of power devices in the inverter configuration creates harmonics that affect the end application behavior and might shorten its lifetime. Furthermore, the resonance frequencies produced by the LCL network contribute to the system instability. This paper proposes a step-by-step guide to designing an LCL filter by considering several key aspects such as the resonance frequency and maximum current ripple. A single-phase grid-connected flyback microinverter with an LCL filter was designed then constructed in the MATLAB/Simulink environment. Several different parameter variations and damping solutions were used to analyze the performance of the circuit. The simulation result shows a promising total harmonic distortion (THD) value below 5% and harmonic suppression up to 14%.
A Review on Various Topologies of Generators, Power Converters and Control Sc...ijtsrd
In the field of renewable energy, conversion of wind energy has become a point of major interest to the researcher. Converters are no more a small part of the wind energy system WES due to the development of generators in the WES and advancement in applications of power electronics in the WES. This paper presents a review of different topologies of converts used in the extraction of energy from wind using various generators and their combination with different converter topologies. Control scheme complexity, cost, the power consumed, and efficiency are the points considered for the comparison of converters-generator combination schemes. Tanuj Jhankal "A Review on Various Topologies of Generators, Power Converters and Control Schemes in Wind Energy Systems" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-6 , October 2021, URL: https://www.ijtsrd.com/papers/ijtsrd47510.pdf Paper URL : https://www.ijtsrd.com/engineering/electrical-engineering/47510/a-review-on-various-topologies-of-generators-power-converters-and-control-schemes-in-wind-energy-systems/tanuj-jhankal
International Journal of Engineering Research and Development is an international premier peer reviewed open access engineering and technology journal promoting the discovery, innovation, advancement and dissemination of basic and transitional knowledge in engineering, technology and related disciplines.
Online Voltage Stability Analysis using Synchrophasor Technologyijsrd.com
Voltage instability has been a major problem in all the emerging power systems across the world. Several instances of blackouts in North America, including the 1996 Western Interconnection and the 2003 North East US /Canada blackout are primarily due to voltage collapse. So Monitoring and maintaining voltage stability in real-time is extremely important for operating a power system reliably. In this paper Synchrophasor technology is introduced. Synchrophasor technology has the capability to monitor voltage stability over a wide area in real time. In this paper different methods are introduced for finding the voltage collapse point in the system and also one new method given for identification of voltage collapse point.
A new bidirectional multilevel inverter topology with a high number of voltage levels with a very reduced number of power components is proposed in this paper. Only TEN power switches and four asymmetric DC voltage sources are used to generate 25 voltage levels in this new topology. The proposed multilevel converter is more suitable for e-mobility and photovoltaic applications where the overall energy source can be composed of a few units/associations of several basic source modules. Several benefits are provided by this new topology: Highly sinusoidal current and voltage waveforms, low Total Harmonic Distortion, very low switching losses, and minimum cost and size of the device. For optimum control of this 25-level voltage inverter, a special Modified Hybrid Modulation technique is performed. The proposed 25-level inverter is compared to various topologies published recently in terms of cost, the number of active power switches, clamped diodes, flying capacitors, DC floating capacitors, and the number of DC voltage sources. This comparison clearly shows that the proposed topology is cost-effective, compact, and very efficient. The effectiveness and the good performance of the proposed multilevel power converter (with and without PWM control) are verified and checked by computational simulations.
IRJET- Enhancement of Power Flow Capability in Power System using UPFC- A RevieWIRJET Journal
This document reviews the use of a Unified Power Flow Controller (UPFC) to enhance power flow capability in power systems. The UPFC is a flexible AC transmission system (FACTS) device that can control both real and reactive power flows on a transmission line. It consists of two voltage source converters connected by a DC link: a static synchronous compensator (STATCOM) and a static synchronous series compensator (SSSC). The STATCOM controls reactive power and the DC link voltage, while the SSSC injects a controlled AC voltage in series with the transmission line to vary the transmission line impedance and power flow. Simulation results show that a UPFC installed on the IEEE 5 bus test system can control power flows and
CONTROL OF BATTERY OPERATED SYSTEM WITH A DC-DC BOOSTCONVERTER FED DSTATCOM U...ijiert bestjournal
This paper presents a comprehensive survey of DSTATCOM control strategies put forward recently. It is
aimed at providing a broad perspective on the status of DSTATCOM control methods to researchers and
application engineers dealing with harmonic suppression issues. Many control techniques have been
designed, developed, and realized for active filters in recent years. The proposed DSTATCOM consists of a
three-leg Voltage Source Converter (VSC) with a dc bus capacitor. The PV array or battery operated boost
converter is proposed to maintain the dc link voltage of the dc bus capacitor for continuous compensation
for the load. This paper presents to evaluate the performance comparison of two control strategies for
extracting the reference currents to control the proposed DSTATCOM. The two control methods are
Synchronous Reference Frame (SRF) theory and IcosΦ algorithm. The performance of the DSTATCOM is
validated using MATLAB software with its simulink and Power System Block set (PSB) toolboxes. The
simulation results for the two control methods are compared to validate the superior performance of the
IcosΦ algorithm.
This document summarizes research determining the optimal location for installing a unified power flow controller (UPFC) in an electric transmission system using particle swarm optimization (PSO) to minimize oscillations. The UPFC regulates voltages and controls power flows. PSO is an efficient method for solving nonlinear optimization problems with constraints. By varying parameters like power angle and incorporating time delays, the approach presents an innovative control scheme to apply UPFC beneficially for economical operation with reduced costs. Sensitivity analysis on the UPFC controller finds the optimal buses to place it and regulate flows.
Voltage Stability Assessment using Phasor Measurement Units in Power Network ...Satyendra Singh
This paper presents the assessment methodology for
voltage stability using Phasor Measurement Unit (PMU) with
complete system observability. For full power system
observability, the PMU placement is considered with and without
conventional power flow as well as injection measurement such
that minimum number of PMU’s is used. Data obtained by
PMU’s are used for voltage stability assessment with the help of
L-Index. As the PMU gives real time voltage and current phasors
and L-index is dependent on voltage and admittance values, thus
the L-index so obtained can be used as real time voltage stability
indicator. The case study has been carried out on IEEE-14 bus
system.
IRJET- Monitoring Against Voltage Instabilities using Line Voltage Stability ...IRJET Journal
This document summarizes methods for monitoring voltage stability in power systems using line voltage stability indices. It analyzes the IEEE 14 bus and IEEE 30 bus test systems to identify weak lines using four indices: line stability index (LMN), fast voltage stability index (FVSI), line stability factor (LQP), and voltage collapse point indicators (VCPI). The results are used to determine which lines are most prone to voltage instability under heavy loading conditions in order to rectify issues by implementing FACTS devices on those lines.
IRJET- A Placement Method of Fuzzy based UPFC to Enhance Voltage Stability Ma...IRJET Journal
This document presents a method for placing a fuzzy logic-based unified power flow controller (UPFC) in a power system network to enhance dynamic voltage stability. Voltage stability indices, including the LQP index and voltage collapse point indicators (VCPI), are used to determine the weakest transmission line under dynamic load variations. The UPFC's shunt and series converters are controlled using fuzzy logic and PI controllers, respectively. Simulations in PSCAD show that placing the fuzzy-based UPFC on the weakest line identified by the indices significantly improves voltage stability in IEEE 5-bus and 14-bus test systems.
Transmission lines react to an unexpected increase in power, and if these power changes are not controlled, some lines will become overloaded on certain routes. Flexible alternating current transmission system (FACTS) devices can change the voltage range and phase angle and thus control the power flow. This paper presents suitable mathematical modeling of FACTS
devices including static var compensator (SVC) as a parallel compensator and high voltage direct current (HVDC) bonding. A comprehensive modeling of SVC and HVDC bonding in the form of simultaneous applications for power flow is also performed, and the effects of compensations are compared. The comprehensive model obtained was implemented on the 5-bus test system in MATLAB software using the Newton-Raphson method, revealed that generators have to produce more power. Also, the addition of these devices stabilizes the voltage and controls active and reactive power in the network.
Direct current (DC) electronic load is a useful equipment for testing the electrical system. It can emulate various load at a high rating. The electronic load requires a power converter to operate and a linear regulator is a common option. Nonetheless, it is hard to control due to the temperature variation. This paper proposed a DC electronic load using the boost converter. The proposed electronic load operates in the continuous current mode and control using the integral controller. The electronic load using the boost converter is compared with the electronic load using the linear regulator. The results show that the boost converter able to operate as an electronic load with an error lower than 0.5% and response time lower than 13 ms.
The hardware implementation of sensorless brushless direct current motor drive incorporating H-infinity control strategy with optimized weights by particle swarm optimization in the speed control is carried out in this work. The methodology involved in the design of brushless direct current (BLDC) motor control with sensorless position detection technique, the design of H-infinity speed controller, steps involved in particle swarm optimization for optimizing coefficients of its weights and the hardware implementation is discussed in detail in this paper. Texas Instruments microcontroller board C2000 Delfino Launchpad LAUNCHXL F28377S and driver BOOSTXL DRV8301 are used for realization of the speed controller. The code is developed using C2000 hardware support package in MATLAB/SIMULINK platform. A comprehensive performance analysis is accomplished during starting of the motor and during the fast application and removal of load. This strategy is found to be robust resulting in faster load disturbance rejection and better reference speed tracking. The experimental results of the proposed strategy are compared with that of conventional proportional-integral (PI) controller. The time domain parameters are also compared. It is found that the proposed strategy exhibits better performance characteristics during transients and sudden disturbances in load.
An inverter system applied with the PV source typically has a problem of lower input voltage due to constraint in the PV strings connection. As a countermeasure a DC-DC boost converter is placed in between to achieve a higher voltage at the inverter DC link for connection to the grid and to realize the MPPT operation. This additional stage contributes to losses and complexity in control thus reducing the overall system efficiency. This work discussed on the design and development of a grid-connected quasi-Z-source PV inverter which has different topology and control method compared to the conventional voltage source inverter and able to overcome the above disadvantages. Modelling and performance analysis of the voltage and current controller to achieve a good power transfer from the PV source, as well sycnchronization with the grid are presented in detail. Results from both simulation and experimental verification demonstrate the designed and developed grid-connected qZSI PV inverter works successfully equivalent to the conventional voltage source inverter system.
Impact of hybrid FACTS devices on the stability of the Kenyan power system IJECEIAES
Flexible alternating current transmission system (FACTS) devices are deployed for improving power system’s stability either singly or as a combination. This research investigates hybrid FACTS devices and studies their impact on voltage, small-signal and transient stability simultaneously under various system disturbances. The simulations were done using five FACTS devices-static var compensator (SVC), static synchronous compensator (STATCOM), static synchronous series compensators (SSSC), thyristor controlled series compensator (TCSC) and unified power flow controller (UPFC) in MATLAB’s power system analysis toolbox (PSAT). These five devices were grouped into ten pairs and tested on Kenya’s transmission network under specific contingencies: the loss of a major generating machine and/or transmission line. The UPFC-STATCOM pair performed the best in all the three aspects under study. The settling times were 3 seconds and 3.05 seconds respectively for voltage and rotor angle improvement on the loss of a major generator at normal operation. The same pair gave settling times of 2.11 seconds and 3.12 seconds for voltage and rotor angle stability improvement respectively on the loss of a major transmission line at 140% system loading. From the study, two novel techniques were developed: A performance-based ranking system and classification for FACTS devices.
The emerging of inductive wireless power transfer (IWPT) technology provides more opportunities for the electric vehicle (EV) battery to have a better recharging process. With the development of IWPT technology, various way of wireless charging of the EV battery is proposed in order to find the best solution. To further understand the fundamentals of the IWPT system itself, an ample review is done. There are different ways of EV charging which are static charging (wired), static wireless charging (SWC) and dynamic wireless charging (DWC). The review starts with a brief comparison of static charging, SWC and DWC. Then, in detailed discussion on the fundamental concepts, related laws and equations that govern the IWPT principle are also included. In this review, the focus is more on the DWC with a little discussion on static charging and SWC to ensure in-depth understanding before one can do further research about the EV charging process. The in-depth perception regarding the development of DWC is elaborated together with the system architecture of the IWPT and DWC system and the different track versions of DWC, which is installable to the road lane.
Mainly the DC motors are employed in most of the application. The main objective is to Regulate the DC motor system. A motor which displays the appearances of a DC motor but there is no commutator and brushes is called as brushless DC motor. These motors are widespread to their compensations than other motors in relationships of dependability, sound, efficiency, preliminary torque and longevity. To achieve the operation more reliable and less noisy, brushless dc motors are employed. In the proposed work, dissimilar methods of speed control are analysed. In real time submission of speed control of BLDC motor, numerous strategies are executed for the speed control singularity. The modified approaches are the employment of PI controller, use of PID controller and proposed current controller.
Design and Experimental Results of Universal Electric Vehicle Charger Using DSPTELKOMNIKA JOURNAL
Owing to the growing concerns over energy depletion and environmental issues around the
world, more and more attention is given on replacing the fuel -based automobiles with electric vehicles
(EVs) which have the characteristics of zero-emission and low noise. As a result, various countries have
taken specific initiatives to de-carbonize their transport sectors by developing their own EV industry.
Regardless of the environmental and economic benefits, substantial scales of grid-connected EVs impose
incredible difficulties to the power grid. The main issues caused by EV charging to the power grid include
harmonics, voltage drop, system instability, system losses and grid overloading. Therefore, this paper
presents design and development of a novel method, which is by applying voltage-oriented control (VOC)
algorithm in battery charging of electric bus.The power system of this work consists of three-phase PWM
rectifier. The proposed method is based on mathematical analysis. Simulation and experimental works are
performed to investigate behavior and performance of the proposed algorithm. This paperclearly described
implementation of low and medium power laboratory prototype and operation of digital signal processor
(DSP) via MATLAB / Simulink for the proposed method.
Design and Performance Analysis of Genetic based PID-PSS with SVC in a Multi-...IDES Editor
Damping of power system oscillations with the help
of proposed optimal Proportional Integral Derivative Power
System Stabilizer (PID-PSS) and Static Var Compensator
(SVC)-based controllers are thoroughly investigated in this
paper. This study presents robust tuning of PID-PSS and
SVC-based controllers using Genetic Algorithms (GA) in
multi machine power systems by considering detailed model
of the generators (model 1.1). The effectiveness of FACTSbased
controllers in general and SVC-based controller in
particular depends upon their proper location. Modal
controllability and observability are used to locate SVC–based
controller. The performance of the proposed controllers is
compared with conventional lead-lag power system stabilizer
(CPSS) and demonstrated on 10 machines, 39 bus New England
test system. Simulation studies show that the proposed genetic
based PID-PSS with SVC based controller provides better
performance.
Alternating current (AC) electrical drives mainly require smaller current (or torque) ripples and lower total harmonic distortion (THD) of voltage for excellent drive performances. Normally, in practice, to achieve these requirements, the inverter needs to be operated at high switching frequency. By operating at high switching frequency, the size of filter can be reduced. However, the inverter which oftenly employs insulated gate bipolar transistor (IGBT) for high power applications cannot be operated at high switching frequency. This is because, the IGBT switching frequency cannot be operated above 50 kHz due to its thermal restrictions. This paper proposes an alternate switching strategy to enable the use of IGBT for operating the inverter at high switching frequency to improve THD performances. In this strategy, each IGBT in a group of switches in the modified inverter circuit will operate the switching frequency at one-fourth of the inverter switching frequency. The alternate switching is implemented using simple analog and digital integrated circuits.
The growing demand for electricity and the increasing integration of clean energies into the electrical grids requires the multiplication and reinforcement of high-voltage direct current (HVDC) projects throughout the world and demonstrates the interest in this electricity transmission technology. The transmitting system of the voltage source converter-high-voltage direct current (VSC-HVDC) consists primarily of two converter stations that are connected by a dc cable. In this paper, a nonlinear control based on the backstepping approach is proposed to improve the dynamic performance of a VSC-HVDC transmission system, these transport systems are characterized by different complexities such as parametric uncertainties, coupled state variables, neglected dynamics, presents a very interesting research topic. Our contribution through adaptive control based on the backstepping approach allows regulating the direct current (DC) bus voltage and the active and reactive powers of the converter stations. Finally, the validity of the proposed control has been verified under various operating conditions by simulation in the MATLAB/Simulink environment.
Recently, LCL has become amongst the most attractive filter used for grid-connected flyback inverters. Nonetheless, the switching of power devices in the inverter configuration creates harmonics that affect the end application behavior and might shorten its lifetime. Furthermore, the resonance frequencies produced by the LCL network contribute to the system instability. This paper proposes a step-by-step guide to designing an LCL filter by considering several key aspects such as the resonance frequency and maximum current ripple. A single-phase grid-connected flyback microinverter with an LCL filter was designed then constructed in the MATLAB/Simulink environment. Several different parameter variations and damping solutions were used to analyze the performance of the circuit. The simulation result shows a promising total harmonic distortion (THD) value below 5% and harmonic suppression up to 14%.
A Review on Various Topologies of Generators, Power Converters and Control Sc...ijtsrd
In the field of renewable energy, conversion of wind energy has become a point of major interest to the researcher. Converters are no more a small part of the wind energy system WES due to the development of generators in the WES and advancement in applications of power electronics in the WES. This paper presents a review of different topologies of converts used in the extraction of energy from wind using various generators and their combination with different converter topologies. Control scheme complexity, cost, the power consumed, and efficiency are the points considered for the comparison of converters-generator combination schemes. Tanuj Jhankal "A Review on Various Topologies of Generators, Power Converters and Control Schemes in Wind Energy Systems" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-6 , October 2021, URL: https://www.ijtsrd.com/papers/ijtsrd47510.pdf Paper URL : https://www.ijtsrd.com/engineering/electrical-engineering/47510/a-review-on-various-topologies-of-generators-power-converters-and-control-schemes-in-wind-energy-systems/tanuj-jhankal
International Journal of Engineering Research and Development is an international premier peer reviewed open access engineering and technology journal promoting the discovery, innovation, advancement and dissemination of basic and transitional knowledge in engineering, technology and related disciplines.
Online Voltage Stability Analysis using Synchrophasor Technologyijsrd.com
Voltage instability has been a major problem in all the emerging power systems across the world. Several instances of blackouts in North America, including the 1996 Western Interconnection and the 2003 North East US /Canada blackout are primarily due to voltage collapse. So Monitoring and maintaining voltage stability in real-time is extremely important for operating a power system reliably. In this paper Synchrophasor technology is introduced. Synchrophasor technology has the capability to monitor voltage stability over a wide area in real time. In this paper different methods are introduced for finding the voltage collapse point in the system and also one new method given for identification of voltage collapse point.
A new bidirectional multilevel inverter topology with a high number of voltage levels with a very reduced number of power components is proposed in this paper. Only TEN power switches and four asymmetric DC voltage sources are used to generate 25 voltage levels in this new topology. The proposed multilevel converter is more suitable for e-mobility and photovoltaic applications where the overall energy source can be composed of a few units/associations of several basic source modules. Several benefits are provided by this new topology: Highly sinusoidal current and voltage waveforms, low Total Harmonic Distortion, very low switching losses, and minimum cost and size of the device. For optimum control of this 25-level voltage inverter, a special Modified Hybrid Modulation technique is performed. The proposed 25-level inverter is compared to various topologies published recently in terms of cost, the number of active power switches, clamped diodes, flying capacitors, DC floating capacitors, and the number of DC voltage sources. This comparison clearly shows that the proposed topology is cost-effective, compact, and very efficient. The effectiveness and the good performance of the proposed multilevel power converter (with and without PWM control) are verified and checked by computational simulations.
IRJET- Enhancement of Power Flow Capability in Power System using UPFC- A RevieWIRJET Journal
This document reviews the use of a Unified Power Flow Controller (UPFC) to enhance power flow capability in power systems. The UPFC is a flexible AC transmission system (FACTS) device that can control both real and reactive power flows on a transmission line. It consists of two voltage source converters connected by a DC link: a static synchronous compensator (STATCOM) and a static synchronous series compensator (SSSC). The STATCOM controls reactive power and the DC link voltage, while the SSSC injects a controlled AC voltage in series with the transmission line to vary the transmission line impedance and power flow. Simulation results show that a UPFC installed on the IEEE 5 bus test system can control power flows and
CONTROL OF BATTERY OPERATED SYSTEM WITH A DC-DC BOOSTCONVERTER FED DSTATCOM U...ijiert bestjournal
This paper presents a comprehensive survey of DSTATCOM control strategies put forward recently. It is
aimed at providing a broad perspective on the status of DSTATCOM control methods to researchers and
application engineers dealing with harmonic suppression issues. Many control techniques have been
designed, developed, and realized for active filters in recent years. The proposed DSTATCOM consists of a
three-leg Voltage Source Converter (VSC) with a dc bus capacitor. The PV array or battery operated boost
converter is proposed to maintain the dc link voltage of the dc bus capacitor for continuous compensation
for the load. This paper presents to evaluate the performance comparison of two control strategies for
extracting the reference currents to control the proposed DSTATCOM. The two control methods are
Synchronous Reference Frame (SRF) theory and IcosΦ algorithm. The performance of the DSTATCOM is
validated using MATLAB software with its simulink and Power System Block set (PSB) toolboxes. The
simulation results for the two control methods are compared to validate the superior performance of the
IcosΦ algorithm.
This document summarizes research determining the optimal location for installing a unified power flow controller (UPFC) in an electric transmission system using particle swarm optimization (PSO) to minimize oscillations. The UPFC regulates voltages and controls power flows. PSO is an efficient method for solving nonlinear optimization problems with constraints. By varying parameters like power angle and incorporating time delays, the approach presents an innovative control scheme to apply UPFC beneficially for economical operation with reduced costs. Sensitivity analysis on the UPFC controller finds the optimal buses to place it and regulate flows.
Voltage Stability Assessment using Phasor Measurement Units in Power Network ...Satyendra Singh
This paper presents the assessment methodology for
voltage stability using Phasor Measurement Unit (PMU) with
complete system observability. For full power system
observability, the PMU placement is considered with and without
conventional power flow as well as injection measurement such
that minimum number of PMU’s is used. Data obtained by
PMU’s are used for voltage stability assessment with the help of
L-Index. As the PMU gives real time voltage and current phasors
and L-index is dependent on voltage and admittance values, thus
the L-index so obtained can be used as real time voltage stability
indicator. The case study has been carried out on IEEE-14 bus
system.
IRJET- Monitoring Against Voltage Instabilities using Line Voltage Stability ...IRJET Journal
This document summarizes methods for monitoring voltage stability in power systems using line voltage stability indices. It analyzes the IEEE 14 bus and IEEE 30 bus test systems to identify weak lines using four indices: line stability index (LMN), fast voltage stability index (FVSI), line stability factor (LQP), and voltage collapse point indicators (VCPI). The results are used to determine which lines are most prone to voltage instability under heavy loading conditions in order to rectify issues by implementing FACTS devices on those lines.
IRJET- A Placement Method of Fuzzy based UPFC to Enhance Voltage Stability Ma...IRJET Journal
This document presents a method for placing a fuzzy logic-based unified power flow controller (UPFC) in a power system network to enhance dynamic voltage stability. Voltage stability indices, including the LQP index and voltage collapse point indicators (VCPI), are used to determine the weakest transmission line under dynamic load variations. The UPFC's shunt and series converters are controlled using fuzzy logic and PI controllers, respectively. Simulations in PSCAD show that placing the fuzzy-based UPFC on the weakest line identified by the indices significantly improves voltage stability in IEEE 5-bus and 14-bus test systems.
In recent days, due to advancement in technology, the end users are facing severe power quality issues. Load flow analysis is one of the fundamental methodologies in solving power network problems. The key importance of Load flow analysis is to improve the performance of distribution network. The main intention of this reserach is to carry out the load flow and voltage stability analysis of 10 bus loop distribution network energized by a generator. Load flow analysis is carried out by using Newton Raphson method. The per unit voltage and angle of the proposed network is determined in all 10 buses by load flow analysis. The voltage stability analysis is implemented by introducing a fault in the network. Here, a power fault is injected at bus 4 between the time interval of 2 to 3 sec to analyse the stability of the system. The voltage stability of the system is analysed for the network with and without automatic voltage regulator (AVR). The AVR unit is tuned by using power system stabilizer (PSS). The results are examined by simulating the network using open modelica connection editor. From the simulation results the per unit voltages and angles at all 10 buses are determined for the network with and without AVR. By comparing both the results it is proved that the network with AVR has better voltage stability than the other. Thus, the voltage stability of the system is improved by connecting the generator with AVR and PSS.
IRJET- Assessment of Voltage Stability in a Power System Network and its Impr...IRJET Journal
The document summarizes a study that assessed voltage stability in a power system network and proposed methods to improve it. The study analyzed losses on each transmission line of a 6-bus, 8-line system using load flow analysis. It identified the weakest bus based on the variation of voltage with respect to reactive power. It then proposed connecting transmission lines with high losses to an on-load tap changing transformer to reduce losses and increase the voltage at the weakest bus, improving stability based on P-V curve analysis. The method was found to effectively improve voltage stability for the test system.
An Innovative Measurement Approach for Load Flow Analysis in MV Smart Grids.SaiSampath16
This document summarizes a technical seminar presented by a group of students on an innovative load flow analysis approach for medium voltage smart grids. The proposed approach uses power quality analyzer measurements at secondary substations and voltage measurements at the primary substation to perform load flow analysis through an iterative backward/forward algorithm. The approach was validated through simulations comparing results to traditional methods and through experimental measurements on an actual medium voltage grid on the island of Ustica, Italy. The results demonstrated the feasibility and accuracy of the proposed lower-cost measurement approach.
Bulk power system availability assessment with multiple wind power plants IJECEIAES
The use of renewable non-conventional energy sources, as wind electric power energy and photovoltaic solar energy, has introduced uncertainties in the performance of bulk power systems. The power system availability has been employed as a useful tool for planning power systems; however, traditional methodologies model generation units as a component with two states: in service or out of service. Nevertheless, this model is not useful to model wind power plants for availability assessment of the power system. This paper used a statistical representation to model the uncertainty of power injection of wind power plants based on the central moments: mean value, variance, skewness and kurtosis. In addition, this paper proposed an availability assessment methodology based on application of this statistical model, and based on the 2m+1 point estimate method the availability assessment is performed. The methodology was tested on the IEEE-RTS assuming the connection of two wind power plants and different correlation among the behavior of these plants.
Influence of Static VAR Compensator for Undervoltage Load Shedding to Avoid V...IJAPEJOURNAL
In the recent years, operation of power systems at lower stability margins has increased the importance of system protection methods that protect the system stability against various disturbances. Among these methods, the load shedding serves as an effective and last-resort tool to prevent system frequency/voltage instability. The analysis of recent blackouts suggests that voltage collapse and voltage-related problems are also important concerns in maintaining system stability. For this reason, voltage also needs to be taken into account in load shedding schemes. This paper considers both parameters in designing a load shedding scheme to determine the amount of load to be shed and its appropriate location .The amount of load to be shed from each bus is decided using the fixed step size method and it’s location has been identified by using voltage collapse proximity index method. SVC is shunt connected FACTS device used to improve the voltage profile of the system. In this paper impact of SVC on load shedding for IEEE 14 bus system has been presented and analyzed.
Gauss-Seidel Method based Voltage Security Analysis of Distribution System IJECEIAES
Complexity of modern power network and Large disturbance results voltage collapse. So, voltage security analysis is important in power system. Indicators are helpful in voltage stability analysis, as they give information about the state of the system. In this paper a new indicator namely Distribution System Stability Indicator (DSSI) has been formulated using the information of Phasor Measurement Unit (PMU).The proposed indicator (DSSI) is tested on standard IEEE 33 bus radial distribution system. The suggested indicator is also applicable to the equivalent two bus system of a multi-bus power system. The proposed indicator is calculated for different contingent conditions at different system load configurations. The result of DSSI is verified with the standard indicator (VSI) which proves applicability of the proposed indicator. The bus voltages of all the buses at base loading and at maximum loading are evaluated for base data and for tripping of most critical line.
Application of Unified Power Flow Controller in Nigeria Power System for Impr...ijtsrd
With the increased rate of urbanization and industrialization, the Nigerian electric power system is being put under pressure, high power losses which has led to fluctuation in voltage level. In this work the Nigeria 330Kv network of 42 bus system was considered. Data for the analysis were obtained from Transmission Company of Nigeria National Control Centre, Osogbo TCN and MATLAB PSAT software with newton Raphson's solution method embedded in it was used to carry out the analysis. The results of the analysis showed that many of the bus voltages were outside the voltage limits of ±5 i.e 0.95pu 1.05pu . After compensation with Flexible AC Transmission System devices FACTs namely Unified Power Flow Controller UPFC which can be used to control power flow on a transmission line, the voltage profile almost flat with bus voltages within acceptable voltage limits. It is also evident that the UPFC is device that can used to combat the voltage problem in the Nigerian electric power system. Adikaibe James | Prof. Engr. F. O. Enemuoh | Aghara Jachimma "Application of Unified Power Flow Controller in Nigeria Power System for Improvement of Voltage Profile" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd27838.pdfPaper URL: https://www.ijtsrd.com/engineering/electrical-engineering/27838/application-of-unified-power-flow-controller-in-nigeria-power-system-for-improvement-of-voltage-profile/adikaibe-james
Identification of Weak and Critical Buses in Electrical Power SystemIRJET Journal
The document summarizes a research paper that identifies weak and critical buses in an electrical power system through voltage stability analysis. It uses the P-V (active power-voltage) curve and P-Q (active power-reactive power) curve methods to analyze voltage stability. The P-V curve method was used to analyze the IEEE 30-bus test system and identify bus 26 as the weakest bus with the lowest active power margin. Identifying weak buses is important for integrating renewable energy sources like wind power and placing reactive power compensators at optimal locations to improve voltage stability.
Selective localization of capacitor banks considering stability aspects in po...IAEME Publication
The issue of voltage stability has become predominant in larger power systems, since the
system is operated close to its capabilities in recent years. Addressing this concern considering the
economic constraints is a challenge .This draws attention towards the localization of the reactive
components that can improve the overall voltage profile in the system. This paper discusses a
methodology for suitable selection of position (bus) for the placement of capacitor bank wherein the
injection of fixed amount of reactive power is made to depict a picture of the overall improved
voltage in the system considering the stability aspect for respective injection at that bus. The reduced
jacobian is used to determine the impact of reactive power injection in the form of system voltage
improvement.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
Voltage Stability Assessment Using the Concept of GVSMiosrjce
To assessment of voltage stability of multi bus power system, the main requirement is equivalent twobus
network models, which is fulfilled by lumping all the series impedances and shunt admittances of
transmission lines within a series equivalent impedance. This paper shows the development of an equivalent pi
network model using a new technology or methodology called generalized global voltage stability margin
(GVSM). This is used to assess the overall voltage stability status of the system accurately. Simulation results
for IEEE 14 Test bus system, IEEE 30 Test bus system , IEEE 118 Test bus system are establish that the piequivalent
model obtained by the proposed method is highly accurate for assessing voltage stability of any
power system at any operating point in a better way as compared to series equivalent model
This document presents a new methodology called generalized global voltage stability margin (GVSM) to assess voltage stability in power systems. The methodology develops an equivalent pi-network model of the power system by lumping all series impedances and shunt admittances of transmission lines. Simulation results on IEEE 14, 30, and 118 test systems show the pi-equivalent model accurately represents the system and allows assessment of voltage stability at any operating point. The GVSM value indicates how close the system is to voltage collapse, and decreases as load increases, becoming zero at the point of collapse. The methodology provides a better representation of voltage stability compared to a traditional series equivalent model.
Load Flow and PV Curve Analysis of a 220kV SubstationIRJET Journal
This document discusses load flow analysis and PV curve analysis of a 220kV substation. It presents the methodology used, which includes collecting data from the substation, developing a bus network model, performing load flow analysis using the Newton-Raphson method in MATLAB, and generating PV curves in PowerWorld simulator. The analysis was conducted on two cases with different circuit configurations. The results show voltages, power flows, line losses and identify the knee point of PV curves. Capacitor compensation is also analyzed, showing it can improve voltage stability. The study highlights the importance of load flow analysis for maintaining power system stability and performance.
IRJET- Comparative Study of Common Methods of Frequency Response using MTDC G...IRJET Journal
This document compares different control strategies for exchanging frequency support between AC power systems connected by a multi-terminal HVDC grid. It studies synthetic inertia control using frequency derivative input, classical frequency droop control, and an integrated synthetic inertia emulation control scheme. Time domain simulations show the impact of these controls on both HVDC grid voltage response and AC system frequency stability. Frequency droop control improves one AC system's frequency at the cost of disturbance to the other. Integrated synthetic inertia emulation control facilitates primary frequency reserve exchange similarly to droop control. The control strategies allow artificial coupling of HVDC-connected AC systems for frequency support.
IRJET- Design and Performance Analysis of Three-Phase Solar PV Integrated UPQCIRJET Journal
1) The document describes a study on the design and performance analysis of a three-phase solar PV integrated unified power quality conditioner (UPQC).
2) The UPQC consists of series and shunt compensators connected back-to-back via a common DC link to improve power quality issues like voltage sag/swell and current harmonics. Solar PV is integrated to provide clean energy and regulate the DC link voltage.
3) Simulation results in MATLAB/Simulink show that the UPQC successfully compensates for voltage sag/swell at the load terminal and regulates the load voltage during disturbances, demonstrating its effectiveness in improving power quality.
Voltage profile enhancement in distribution network using static synchronous ...IJECEIAES
STATCOM is one of FACTS devices that used as regulator for transmission and distribution systems which works for reactive power compensation. STATCOM utilisation in distribution system mostly for enhancing the profile of voltage, where used for adjusting the disturbance voltage by injecting into the system a controllable voltage. This paper present a Fuzzy controller based on STATCOM to enhance the voltage profile in distribution network. The controller of STATCOM has simulated for different types of abnormal load conditions of balance and unbalance load. The results of simulation show ability of proposed design to enhance the load voltage which was 96% of the nominal value.
Current control scheme is commonly used in high voltage direct current (HVDC) to transmit power delivery. This scheme is done by adjusting trigger angle to regulate direct current (DC) in thyristor devices. The adaptive neuro-fuzzy inference system (ANFIS) control is widely applied for start and fault operation. But, solution for transient response of DC current in HVDC system is not clearly studied before. In this paper, supplementary control (SC) based on ANFIS is proposed to improve the transient response of the current. The SC control is designed by learning-processes and SC parameters are obtained by data-training automatically. For current reference at 1.05 pu and up-ramp at 20 pu/s, maximum overshoot is achieved at 5.12% and 7.72% for the SC and proportional integral controller (PIC), respectively. When the up-ramp is increased to 28 pu/s, the maximum overshoot is achieved at 10.01% for the SC. While, the peak overshoot for the PIC is 14.28%.
Similar to Online monitoring of voltage stability margin using PMU measurements (20)
Redefining brain tumor segmentation: a cutting-edge convolutional neural netw...IJECEIAES
Medical image analysis has witnessed significant advancements with deep learning techniques. In the domain of brain tumor segmentation, the ability to
precisely delineate tumor boundaries from magnetic resonance imaging (MRI)
scans holds profound implications for diagnosis. This study presents an ensemble convolutional neural network (CNN) with transfer learning, integrating
the state-of-the-art Deeplabv3+ architecture with the ResNet18 backbone. The
model is rigorously trained and evaluated, exhibiting remarkable performance
metrics, including an impressive global accuracy of 99.286%, a high-class accuracy of 82.191%, a mean intersection over union (IoU) of 79.900%, a weighted
IoU of 98.620%, and a Boundary F1 (BF) score of 83.303%. Notably, a detailed comparative analysis with existing methods showcases the superiority of
our proposed model. These findings underscore the model’s competence in precise brain tumor localization, underscoring its potential to revolutionize medical
image analysis and enhance healthcare outcomes. This research paves the way
for future exploration and optimization of advanced CNN models in medical
imaging, emphasizing addressing false positives and resource efficiency.
Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.
Advanced control scheme of doubly fed induction generator for wind turbine us...IJECEIAES
This paper describes a speed control device for generating electrical energy on an electricity network based on the doubly fed induction generator (DFIG) used for wind power conversion systems. At first, a double-fed induction generator model was constructed. A control law is formulated to govern the flow of energy between the stator of a DFIG and the energy network using three types of controllers: proportional integral (PI), sliding mode controller (SMC) and second order sliding mode controller (SOSMC). Their different results in terms of power reference tracking, reaction to unexpected speed fluctuations, sensitivity to perturbations, and resilience against machine parameter alterations are compared. MATLAB/Simulink was used to conduct the simulations for the preceding study. Multiple simulations have shown very satisfying results, and the investigations demonstrate the efficacy and power-enhancing capabilities of the suggested control system.
Neural network optimizer of proportional-integral-differential controller par...IJECEIAES
Wide application of proportional-integral-differential (PID)-regulator in industry requires constant improvement of methods of its parameters adjustment. The paper deals with the issues of optimization of PID-regulator parameters with the use of neural network technology methods. A methodology for choosing the architecture (structure) of neural network optimizer is proposed, which consists in determining the number of layers, the number of neurons in each layer, as well as the form and type of activation function. Algorithms of neural network training based on the application of the method of minimizing the mismatch between the regulated value and the target value are developed. The method of back propagation of gradients is proposed to select the optimal training rate of neurons of the neural network. The neural network optimizer, which is a superstructure of the linear PID controller, allows increasing the regulation accuracy from 0.23 to 0.09, thus reducing the power consumption from 65% to 53%. The results of the conducted experiments allow us to conclude that the created neural superstructure may well become a prototype of an automatic voltage regulator (AVR)-type industrial controller for tuning the parameters of the PID controller.
An improved modulation technique suitable for a three level flying capacitor ...IJECEIAES
This research paper introduces an innovative modulation technique for controlling a 3-level flying capacitor multilevel inverter (FCMLI), aiming to streamline the modulation process in contrast to conventional methods. The proposed
simplified modulation technique paves the way for more straightforward and
efficient control of multilevel inverters, enabling their widespread adoption and
integration into modern power electronic systems. Through the amalgamation of
sinusoidal pulse width modulation (SPWM) with a high-frequency square wave
pulse, this controlling technique attains energy equilibrium across the coupling
capacitor. The modulation scheme incorporates a simplified switching pattern
and a decreased count of voltage references, thereby simplifying the control
algorithm.
A review on features and methods of potential fishing zoneIJECEIAES
This review focuses on the importance of identifying potential fishing zones in seawater for sustainable fishing practices. It explores features like sea surface temperature (SST) and sea surface height (SSH), along with classification methods such as classifiers. The features like SST, SSH, and different classifiers used to classify the data, have been figured out in this review study. This study underscores the importance of examining potential fishing zones using advanced analytical techniques. It thoroughly explores the methodologies employed by researchers, covering both past and current approaches. The examination centers on data characteristics and the application of classification algorithms for classification of potential fishing zones. Furthermore, the prediction of potential fishing zones relies significantly on the effectiveness of classification algorithms. Previous research has assessed the performance of models like support vector machines, naïve Bayes, and artificial neural networks (ANN). In the previous result, the results of support vector machine (SVM) were 97.6% more accurate than naive Bayes's 94.2% to classify test data for fisheries classification. By considering the recent works in this area, several recommendations for future works are presented to further improve the performance of the potential fishing zone models, which is important to the fisheries community.
Electrical signal interference minimization using appropriate core material f...IJECEIAES
As demand for smaller, quicker, and more powerful devices rises, Moore's law is strictly followed. The industry has worked hard to make little devices that boost productivity. The goal is to optimize device density. Scientists are reducing connection delays to improve circuit performance. This helped them understand three-dimensional integrated circuit (3D IC) concepts, which stack active devices and create vertical connections to diminish latency and lower interconnects. Electrical involvement is a big worry with 3D integrates circuits. Researchers have developed and tested through silicon via (TSV) and substrates to decrease electrical wave involvement. This study illustrates a novel noise coupling reduction method using several electrical involvement models. A 22% drop in electrical involvement from wave-carrying to victim TSVs introduces this new paradigm and improves system performance even at higher THz frequencies.
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...IJECEIAES
Climate change's impact on the planet forced the United Nations and governments to promote green energies and electric transportation. The deployments of photovoltaic (PV) and electric vehicle (EV) systems gained stronger momentum due to their numerous advantages over fossil fuel types. The advantages go beyond sustainability to reach financial support and stability. The work in this paper introduces the hybrid system between PV and EV to support industrial and commercial plants. This paper covers the theoretical framework of the proposed hybrid system including the required equation to complete the cost analysis when PV and EV are present. In addition, the proposed design diagram which sets the priorities and requirements of the system is presented. The proposed approach allows setup to advance their power stability, especially during power outages. The presented information supports researchers and plant owners to complete the necessary analysis while promoting the deployment of clean energy. The result of a case study that represents a dairy milk farmer supports the theoretical works and highlights its advanced benefits to existing plants. The short return on investment of the proposed approach supports the paper's novelty approach for the sustainable electrical system. In addition, the proposed system allows for an isolated power setup without the need for a transmission line which enhances the safety of the electrical network
Bibliometric analysis highlighting the role of women in addressing climate ch...IJECEIAES
Fossil fuel consumption increased quickly, contributing to climate change
that is evident in unusual flooding and draughts, and global warming. Over
the past ten years, women's involvement in society has grown dramatically,
and they succeeded in playing a noticeable role in reducing climate change.
A bibliometric analysis of data from the last ten years has been carried out to
examine the role of women in addressing the climate change. The analysis's
findings discussed the relevant to the sustainable development goals (SDGs),
particularly SDG 7 and SDG 13. The results considered contributions made
by women in the various sectors while taking geographic dispersion into
account. The bibliometric analysis delves into topics including women's
leadership in environmental groups, their involvement in policymaking, their
contributions to sustainable development projects, and the influence of
gender diversity on attempts to mitigate climate change. This study's results
highlight how women have influenced policies and actions related to climate
change, point out areas of research deficiency and recommendations on how
to increase role of the women in addressing the climate change and
achieving sustainability. To achieve more successful results, this initiative
aims to highlight the significance of gender equality and encourage
inclusivity in climate change decision-making processes.
Voltage and frequency control of microgrid in presence of micro-turbine inter...IJECEIAES
The active and reactive load changes have a significant impact on voltage
and frequency. In this paper, in order to stabilize the microgrid (MG) against
load variations in islanding mode, the active and reactive power of all
distributed generators (DGs), including energy storage (battery), diesel
generator, and micro-turbine, are controlled. The micro-turbine generator is
connected to MG through a three-phase to three-phase matrix converter, and
the droop control method is applied for controlling the voltage and
frequency of MG. In addition, a method is introduced for voltage and
frequency control of micro-turbines in the transition state from gridconnected mode to islanding mode. A novel switching strategy of the matrix
converter is used for converting the high-frequency output voltage of the
micro-turbine to the grid-side frequency of the utility system. Moreover,
using the switching strategy, the low-order harmonics in the output current
and voltage are not produced, and consequently, the size of the output filter
would be reduced. In fact, the suggested control strategy is load-independent
and has no frequency conversion restrictions. The proposed approach for
voltage and frequency regulation demonstrates exceptional performance and
favorable response across various load alteration scenarios. The suggested
strategy is examined in several scenarios in the MG test systems, and the
simulation results are addressed.
Enhancing battery system identification: nonlinear autoregressive modeling fo...IJECEIAES
Precisely characterizing Li-ion batteries is essential for optimizing their
performance, enhancing safety, and prolonging their lifespan across various
applications, such as electric vehicles and renewable energy systems. This
article introduces an innovative nonlinear methodology for system
identification of a Li-ion battery, employing a nonlinear autoregressive with
exogenous inputs (NARX) model. The proposed approach integrates the
benefits of nonlinear modeling with the adaptability of the NARX structure,
facilitating a more comprehensive representation of the intricate
electrochemical processes within the battery. Experimental data collected
from a Li-ion battery operating under diverse scenarios are employed to
validate the effectiveness of the proposed methodology. The identified
NARX model exhibits superior accuracy in predicting the battery's behavior
compared to traditional linear models. This study underscores the
importance of accounting for nonlinearities in battery modeling, providing
insights into the intricate relationships between state-of-charge, voltage, and
current under dynamic conditions.
Smart grid deployment: from a bibliometric analysis to a surveyIJECEIAES
Smart grids are one of the last decades' innovations in electrical energy.
They bring relevant advantages compared to the traditional grid and
significant interest from the research community. Assessing the field's
evolution is essential to propose guidelines for facing new and future smart
grid challenges. In addition, knowing the main technologies involved in the
deployment of smart grids (SGs) is important to highlight possible
shortcomings that can be mitigated by developing new tools. This paper
contributes to the research trends mentioned above by focusing on two
objectives. First, a bibliometric analysis is presented to give an overview of
the current research level about smart grid deployment. Second, a survey of
the main technological approaches used for smart grid implementation and
their contributions are highlighted. To that effect, we searched the Web of
Science (WoS), and the Scopus databases. We obtained 5,663 documents
from WoS and 7,215 from Scopus on smart grid implementation or
deployment. With the extraction limitation in the Scopus database, 5,872 of
the 7,215 documents were extracted using a multi-step process. These two
datasets have been analyzed using a bibliometric tool called bibliometrix.
The main outputs are presented with some recommendations for future
research.
Use of analytical hierarchy process for selecting and prioritizing islanding ...IJECEIAES
One of the problems that are associated to power systems is islanding
condition, which must be rapidly and properly detected to prevent any
negative consequences on the system's protection, stability, and security.
This paper offers a thorough overview of several islanding detection
strategies, which are divided into two categories: classic approaches,
including local and remote approaches, and modern techniques, including
techniques based on signal processing and computational intelligence.
Additionally, each approach is compared and assessed based on several
factors, including implementation costs, non-detected zones, declining
power quality, and response times using the analytical hierarchy process
(AHP). The multi-criteria decision-making analysis shows that the overall
weight of passive methods (24.7%), active methods (7.8%), hybrid methods
(5.6%), remote methods (14.5%), signal processing-based methods (26.6%),
and computational intelligent-based methods (20.8%) based on the
comparison of all criteria together. Thus, it can be seen from the total weight
that hybrid approaches are the least suitable to be chosen, while signal
processing-based methods are the most appropriate islanding detection
method to be selected and implemented in power system with respect to the
aforementioned factors. Using Expert Choice software, the proposed
hierarchy model is studied and examined.
Enhancing of single-stage grid-connected photovoltaic system using fuzzy logi...IJECEIAES
The power generated by photovoltaic (PV) systems is influenced by
environmental factors. This variability hampers the control and utilization of
solar cells' peak output. In this study, a single-stage grid-connected PV
system is designed to enhance power quality. Our approach employs fuzzy
logic in the direct power control (DPC) of a three-phase voltage source
inverter (VSI), enabling seamless integration of the PV connected to the
grid. Additionally, a fuzzy logic-based maximum power point tracking
(MPPT) controller is adopted, which outperforms traditional methods like
incremental conductance (INC) in enhancing solar cell efficiency and
minimizing the response time. Moreover, the inverter's real-time active and
reactive power is directly managed to achieve a unity power factor (UPF).
The system's performance is assessed through MATLAB/Simulink
implementation, showing marked improvement over conventional methods,
particularly in steady-state and varying weather conditions. For solar
irradiances of 500 and 1,000 W/m2
, the results show that the proposed
method reduces the total harmonic distortion (THD) of the injected current
to the grid by approximately 46% and 38% compared to conventional
methods, respectively. Furthermore, we compare the simulation results with
IEEE standards to evaluate the system's grid compatibility.
Enhancing photovoltaic system maximum power point tracking with fuzzy logic-b...IJECEIAES
Photovoltaic systems have emerged as a promising energy resource that
caters to the future needs of society, owing to their renewable, inexhaustible,
and cost-free nature. The power output of these systems relies on solar cell
radiation and temperature. In order to mitigate the dependence on
atmospheric conditions and enhance power tracking, a conventional
approach has been improved by integrating various methods. To optimize
the generation of electricity from solar systems, the maximum power point
tracking (MPPT) technique is employed. To overcome limitations such as
steady-state voltage oscillations and improve transient response, two
traditional MPPT methods, namely fuzzy logic controller (FLC) and perturb
and observe (P&O), have been modified. This research paper aims to
simulate and validate the step size of the proposed modified P&O and FLC
techniques within the MPPT algorithm using MATLAB/Simulink for
efficient power tracking in photovoltaic systems.
Adaptive synchronous sliding control for a robot manipulator based on neural ...IJECEIAES
Robot manipulators have become important equipment in production lines, medical fields, and transportation. Improving the quality of trajectory tracking for
robot hands is always an attractive topic in the research community. This is a
challenging problem because robot manipulators are complex nonlinear systems
and are often subject to fluctuations in loads and external disturbances. This
article proposes an adaptive synchronous sliding control scheme to improve trajectory tracking performance for a robot manipulator. The proposed controller
ensures that the positions of the joints track the desired trajectory, synchronize
the errors, and significantly reduces chattering. First, the synchronous tracking
errors and synchronous sliding surfaces are presented. Second, the synchronous
tracking error dynamics are determined. Third, a robust adaptive control law is
designed,the unknown components of the model are estimated online by the neural network, and the parameters of the switching elements are selected by fuzzy
logic. The built algorithm ensures that the tracking and approximation errors
are ultimately uniformly bounded (UUB). Finally, the effectiveness of the constructed algorithm is demonstrated through simulation and experimental results.
Simulation and experimental results show that the proposed controller is effective with small synchronous tracking errors, and the chattering phenomenon is
significantly reduced.
Remote field-programmable gate array laboratory for signal acquisition and de...IJECEIAES
A remote laboratory utilizing field-programmable gate array (FPGA) technologies enhances students’ learning experience anywhere and anytime in embedded system design. Existing remote laboratories prioritize hardware access and visual feedback for observing board behavior after programming, neglecting comprehensive debugging tools to resolve errors that require internal signal acquisition. This paper proposes a novel remote embeddedsystem design approach targeting FPGA technologies that are fully interactive via a web-based platform. Our solution provides FPGA board access and debugging capabilities beyond the visual feedback provided by existing remote laboratories. We implemented a lab module that allows users to seamlessly incorporate into their FPGA design. The module minimizes hardware resource utilization while enabling the acquisition of a large number of data samples from the signal during the experiments by adaptively compressing the signal prior to data transmission. The results demonstrate an average compression ratio of 2.90 across three benchmark signals, indicating efficient signal acquisition and effective debugging and analysis. This method allows users to acquire more data samples than conventional methods. The proposed lab allows students to remotely test and debug their designs, bridging the gap between theory and practice in embedded system design.
Detecting and resolving feature envy through automated machine learning and m...IJECEIAES
Efficiently identifying and resolving code smells enhances software project quality. This paper presents a novel solution, utilizing automated machine learning (AutoML) techniques, to detect code smells and apply move method refactoring. By evaluating code metrics before and after refactoring, we assessed its impact on coupling, complexity, and cohesion. Key contributions of this research include a unique dataset for code smell classification and the development of models using AutoGluon for optimal performance. Furthermore, the study identifies the top 20 influential features in classifying feature envy, a well-known code smell, stemming from excessive reliance on external classes. We also explored how move method refactoring addresses feature envy, revealing reduced coupling and complexity, and improved cohesion, ultimately enhancing code quality. In summary, this research offers an empirical, data-driven approach, integrating AutoML and move method refactoring to optimize software project quality. Insights gained shed light on the benefits of refactoring on code quality and the significance of specific features in detecting feature envy. Future research can expand to explore additional refactoring techniques and a broader range of code metrics, advancing software engineering practices and standards.
Smart monitoring technique for solar cell systems using internet of things ba...IJECEIAES
Rapidly and remotely monitoring and receiving the solar cell systems status parameters, solar irradiance, temperature, and humidity, are critical issues in enhancement their efficiency. Hence, in the present article an improved smart prototype of internet of things (IoT) technique based on embedded system through NodeMCU ESP8266 (ESP-12E) was carried out experimentally. Three different regions at Egypt; Luxor, Cairo, and El-Beheira cities were chosen to study their solar irradiance profile, temperature, and humidity by the proposed IoT system. The monitoring data of solar irradiance, temperature, and humidity were live visualized directly by Ubidots through hypertext transfer protocol (HTTP) protocol. The measured solar power radiation in Luxor, Cairo, and El-Beheira ranged between 216-1000, 245-958, and 187-692 W/m 2 respectively during the solar day. The accuracy and rapidity of obtaining monitoring results using the proposed IoT system made it a strong candidate for application in monitoring solar cell systems. On the other hand, the obtained solar power radiation results of the three considered regions strongly candidate Luxor and Cairo as suitable places to build up a solar cells system station rather than El-Beheira.
An efficient security framework for intrusion detection and prevention in int...IJECEIAES
Over the past few years, the internet of things (IoT) has advanced to connect billions of smart devices to improve quality of life. However, anomalies or malicious intrusions pose several security loopholes, leading to performance degradation and threat to data security in IoT operations. Thereby, IoT security systems must keep an eye on and restrict unwanted events from occurring in the IoT network. Recently, various technical solutions based on machine learning (ML) models have been derived towards identifying and restricting unwanted events in IoT. However, most ML-based approaches are prone to miss-classification due to inappropriate feature selection. Additionally, most ML approaches applied to intrusion detection and prevention consider supervised learning, which requires a large amount of labeled data to be trained. Consequently, such complex datasets are impossible to source in a large network like IoT. To address this problem, this proposed study introduces an efficient learning mechanism to strengthen the IoT security aspects. The proposed algorithm incorporates supervised and unsupervised approaches to improve the learning models for intrusion detection and mitigation. Compared with the related works, the experimental outcome shows that the model performs well in a benchmark dataset. It accomplishes an improved detection accuracy of approximately 99.21%.
International Conference on NLP, Artificial Intelligence, Machine Learning an...gerogepatton
International Conference on NLP, Artificial Intelligence, Machine Learning and Applications (NLAIM 2024) offers a premier global platform for exchanging insights and findings in the theory, methodology, and applications of NLP, Artificial Intelligence, Machine Learning, and their applications. The conference seeks substantial contributions across all key domains of NLP, Artificial Intelligence, Machine Learning, and their practical applications, aiming to foster both theoretical advancements and real-world implementations. With a focus on facilitating collaboration between researchers and practitioners from academia and industry, the conference serves as a nexus for sharing the latest developments in the field.
Optimizing Gradle Builds - Gradle DPE Tour Berlin 2024Sinan KOZAK
Sinan from the Delivery Hero mobile infrastructure engineering team shares a deep dive into performance acceleration with Gradle build cache optimizations. Sinan shares their journey into solving complex build-cache problems that affect Gradle builds. By understanding the challenges and solutions found in our journey, we aim to demonstrate the possibilities for faster builds. The case study reveals how overlapping outputs and cache misconfigurations led to significant increases in build times, especially as the project scaled up with numerous modules using Paparazzi tests. The journey from diagnosing to defeating cache issues offers invaluable lessons on maintaining cache integrity without sacrificing functionality.
Comparative analysis between traditional aquaponics and reconstructed aquapon...bijceesjournal
The aquaponic system of planting is a method that does not require soil usage. It is a method that only needs water, fish, lava rocks (a substitute for soil), and plants. Aquaponic systems are sustainable and environmentally friendly. Its use not only helps to plant in small spaces but also helps reduce artificial chemical use and minimizes excess water use, as aquaponics consumes 90% less water than soil-based gardening. The study applied a descriptive and experimental design to assess and compare conventional and reconstructed aquaponic methods for reproducing tomatoes. The researchers created an observation checklist to determine the significant factors of the study. The study aims to determine the significant difference between traditional aquaponics and reconstructed aquaponics systems propagating tomatoes in terms of height, weight, girth, and number of fruits. The reconstructed aquaponics system’s higher growth yield results in a much more nourished crop than the traditional aquaponics system. It is superior in its number of fruits, height, weight, and girth measurement. Moreover, the reconstructed aquaponics system is proven to eliminate all the hindrances present in the traditional aquaponics system, which are overcrowding of fish, algae growth, pest problems, contaminated water, and dead fish.
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
Understanding Inductive Bias in Machine LearningSUTEJAS
This presentation explores the concept of inductive bias in machine learning. It explains how algorithms come with built-in assumptions and preferences that guide the learning process. You'll learn about the different types of inductive bias and how they can impact the performance and generalizability of machine learning models.
The presentation also covers the positive and negative aspects of inductive bias, along with strategies for mitigating potential drawbacks. We'll explore examples of how bias manifests in algorithms like neural networks and decision trees.
By understanding inductive bias, you can gain valuable insights into how machine learning models work and make informed decisions when building and deploying them.
TIME DIVISION MULTIPLEXING TECHNIQUE FOR COMMUNICATION SYSTEMHODECEDSIET
Time Division Multiplexing (TDM) is a method of transmitting multiple signals over a single communication channel by dividing the signal into many segments, each having a very short duration of time. These time slots are then allocated to different data streams, allowing multiple signals to share the same transmission medium efficiently. TDM is widely used in telecommunications and data communication systems.
### How TDM Works
1. **Time Slots Allocation**: The core principle of TDM is to assign distinct time slots to each signal. During each time slot, the respective signal is transmitted, and then the process repeats cyclically. For example, if there are four signals to be transmitted, the TDM cycle will divide time into four slots, each assigned to one signal.
2. **Synchronization**: Synchronization is crucial in TDM systems to ensure that the signals are correctly aligned with their respective time slots. Both the transmitter and receiver must be synchronized to avoid any overlap or loss of data. This synchronization is typically maintained by a clock signal that ensures time slots are accurately aligned.
3. **Frame Structure**: TDM data is organized into frames, where each frame consists of a set of time slots. Each frame is repeated at regular intervals, ensuring continuous transmission of data streams. The frame structure helps in managing the data streams and maintaining the synchronization between the transmitter and receiver.
4. **Multiplexer and Demultiplexer**: At the transmitting end, a multiplexer combines multiple input signals into a single composite signal by assigning each signal to a specific time slot. At the receiving end, a demultiplexer separates the composite signal back into individual signals based on their respective time slots.
### Types of TDM
1. **Synchronous TDM**: In synchronous TDM, time slots are pre-assigned to each signal, regardless of whether the signal has data to transmit or not. This can lead to inefficiencies if some time slots remain empty due to the absence of data.
2. **Asynchronous TDM (or Statistical TDM)**: Asynchronous TDM addresses the inefficiencies of synchronous TDM by allocating time slots dynamically based on the presence of data. Time slots are assigned only when there is data to transmit, which optimizes the use of the communication channel.
### Applications of TDM
- **Telecommunications**: TDM is extensively used in telecommunication systems, such as in T1 and E1 lines, where multiple telephone calls are transmitted over a single line by assigning each call to a specific time slot.
- **Digital Audio and Video Broadcasting**: TDM is used in broadcasting systems to transmit multiple audio or video streams over a single channel, ensuring efficient use of bandwidth.
- **Computer Networks**: TDM is used in network protocols and systems to manage the transmission of data from multiple sources over a single network medium.
### Advantages of TDM
- **Efficient Use of Bandwidth**: TDM all
Batteries -Introduction – Types of Batteries – discharging and charging of battery - characteristics of battery –battery rating- various tests on battery- – Primary battery: silver button cell- Secondary battery :Ni-Cd battery-modern battery: lithium ion battery-maintenance of batteries-choices of batteries for electric vehicle applications.
Fuel Cells: Introduction- importance and classification of fuel cells - description, principle, components, applications of fuel cells: H2-O2 fuel cell, alkaline fuel cell, molten carbonate fuel cell and direct methanol fuel cells.
2. Int J Elec & Comp Eng ISSN: 2088-8708
Online monitoring of voltage stability margin using PMU measurements (Pankaj Sahu)
1157
measurements by PMUs. Online estimation of voltage stability margin through matching of critical load
impedance with PMU measurements based Thevenin’s impedance of the rest of the network has been
proposed [9–12]. Representation of whole network connected across a critical load bus may be suitable for
voltage stability monitoring of radial networks. However, interconnected power system may have a critical
area comprising of a set of critical load buses prone to voltage collapse. Thevenin’s equivalent of critical load
area based on PMU measurements at its surrounding buses has been proposed [13, 14]. All the buses in
the critical load area have been merged to replace these by a fictitious load bus. A critical load area is fed by
multiple tie-lines, in general. Some of these may have over flows that may lead to voltage instability in
the area. Replacing all the buses in the area with a single equivalent bus merges all the tie-lines too into
a fictitious equivalent tie-line. Therefore, tie-lines of original network having overflows and hence being
responsible for instability cannot be detected. In order to address this issue, online monitoring of voltage
stability margin of a load area based on tie-line flows has been proposed [15]. Tie-line flows have been
obtained through phasor measurements performed by PMUs placed at boundary buses of the critical load
area. However, critical load areas are dependent upon operating conditions and topology of the network.
Change of network topology due to occurrence of contingencies may lead to emergence of new critical load
areas where PMUs are not placed.
Distributed linear algorithm has been proposed for online computation of voltage stability proximity
indices (VCPI) based on local phasor measurements performed at all the load buses [16].
PMU measurements based online monitoring of critical buses using Q-V (reactive power-voltage magnitude)
and P-Ө (real power-voltage angle) sensitivities has been proposed [17]. However, assumption of Q-Ө and
P-V decoupling are not valid near nose point. A normalized P-index has been proposed for online monitoring
of voltage stability using phasor measurements [18]. However, P-index has been developed assuming
constant power factor under increased demand which is not valid for real time systems.
Online monitoring of voltage stability based on Thevenin’s equivalent of the network [9-15], as well
as sensitivity based real time estimation of voltage stability margin [16-18] may fail to produce satisfactory
results in case of large disturbances due to highly non-linear behavior of power systems. An Artificial Neural
Network (ANN) based monitoring of voltage stability based on phasor measurements has been
proposed [19]. Proper training of ANN is still a challenge. Enhanced-Online-Random-Forest (EORF) model
has been proposed based on voltage phasor measurements for online monitoring of voltage stability [20].
EORF model updates voltage stability information under change in operating conditions/network topology
using fresh PMU measurements at important load buses. EORF model may lead sometimes to erroneous
estimation of voltage stability margin due to non-consideration of voltage phasor information of remaining
buses. A general method to adjust loads at the receiving end has been applied to determine the proximity to
voltage collapse [21]. Here, it is concluded that the intermediate load adjustment improves the accuracy of
the indices. In this the PMUs are not placed optimally in the system. In most of the research the statistical
information obtained from PMUs has not actionably used to improve the voltage stability. In [22], the new
method has been suggested that gauges and improves the voltage stability of a system using statistical data
obtained from PMUs.
In this paper, real time determination of nose curve of all the load buses based on three successive
PMU measurements and pseudo-measurements is performed. Minimum out of maximum loadability of all
the load buses has been considered as the loading margin of the system. Voltage stability information is
updated with new PMU measurements obtained. Thus, proposed approach is capable of monitoring voltage
stability of real time systems as change in system operating conditions and network topology is considered by
updated PMU measurements performed at regular intervals. PMUs have been optimally placed in the system
based on result of binary integer linear programming ensuring full network observability even in case of loss
of few PMUs under contingencies [23]. Paper is structured as follows: Section II presents methodology
proposed for online monitoring of voltage stability margin using PMU measurements based quadratic fitting
of nose curves. Section III validates effectiveness of proposed approach based on case studies performed on
standard IEEE 14-bus system, New England 39-bus system and a practical 246-bus Indian system
representing power network of nine states and union territories of India. Section IV concludes summarizing
important contributions of the proposed work.
2. METHODOLOGY
Proposed approach of online monitoring of voltage stability margin using phasor measurements is
presented: Real power demand ( iDP ) versus voltage magnitude iV curve (P-V curve) of bus-i shown in
Figure 1 may be approximately obtained by solution of quadratic equation,
3. ISSN: 2088-8708
Int J Elec & Comp Eng, Vol. 10, No. 2, April 2020 : 1156 - 1168
1158
2
1 2 3iD i i i i iP a V a V a (1)
where, 1ia , 2ia and 3ia are constants
Differentiating iDP
with respect to iV ,
1 22iD
i i i
i
dP
a V a
dV
(2)
At nose point of P-V curve, iD
i
dP
dV
= 0. Therefore, from (2),
2
12
np i
i
i
a
V
a
(3)
where,
np
iV = voltage magnitude of bus-i at the nose point of P-V curve shown in Figure1. From (1) and (3),
2
2
3
14i
n i
D i
i
a
P a
a
(4)
where,
i
n
DP = Real power demand of bus-i at the nose point of P-V curve shown in Figure 1.
Figure 1. P-V curve of bus-i
Reactive power demand ( iDQ ) versus voltage magnitude ( iV ) curve (Q-V curve) of bus-i shown in
Figure 2 may be approximately obtained by solution of quadratic equation,
2
1 2 3iD i i i i iQ b V b V b (5)
where, 1ib , 2ib and 3ib are constants.
4. Int J Elec & Comp Eng ISSN: 2088-8708
Online monitoring of voltage stability margin using PMU measurements (Pankaj Sahu)
1159
Figure 2. Q-V curve of bus-i
Differentiating iDQ with respect to iV ,
1 22iD
i i i
i
dQ
b V b
dV
(6)
At the nose point of Q-V curve, iD
i
dQ
dV
= 0, Therefore, from (6),
2
12
nq i
i
i
b
V
b
(7)
where,
nq
iV = voltage magnitude of bus-i at the nose point of Q-V curve shown in Figure 2. From (5)
and (7),
2
2
3
14i
n i
D i
i
b
Q b
b
(8)
where, i
n
DQ = Reactive power demand of bus-i at the nose point of Q-V curve shown in Figure 2. Constants
1ia , 2ia and 3ia were obtained by solution of equations:
1 1 2 1
1 2 3( )iD i i i i iP a V a V a (9)
2 2 2 2
1 2 3( )iD i i i i iP a V a V a (10)
3 3 2 3
1 2 3( )iD i i i i iP a V a V a (11)
where,
1
iV ,
2
iV ,
3
iV shown in Figure 1 and in Figure 2 correspond to voltage magnitude of bus-i at
operating points 1, 2 and 3, respectively, and
1
iDP ,
2
iDP and
3
iDP shown in Figure 1 correspond to real power
demand of bus-i at operating points 1, 2 and 3, respectively.
Evaluated constants 1ia , 2ia and 3ia were used to find real power loading margin of bus-i
using (4). Constants 1ib , 2ib and 3ib are obtained by solution of equations:
1 1 2 1
1 2 3( )iD i i i i iQ b V b V b (12)
5. ISSN: 2088-8708
Int J Elec & Comp Eng, Vol. 10, No. 2, April 2020 : 1156 - 1168
1160
2 2 2 2
1 2 3( )iD i i i i iQ b V b V b (13)
3 3 2 3
1 2 3( )iD i i i i iQ b V b V b (14)
where,
1
iDQ ,
2
iDQ and
3
iDQ shown in Figure 2 correspond to reactive power demand of bus-i at operating
points 1, 2 and 3, respectively.
Evaluated constants 1ib , 2ib and 3ib were used to find reactive power loading margin of bus-i
using (8). Constants a1i, a2i, a3i, b1i, b2i and b3i for each of the load buses were evaluated using voltage
magnitude, real power demand and reactive power demand obtained by PMU measurements/pseudo
measurements performed at operating points 1, 2 and 3, respectively. Evaluated constants predict real power
loading margin as well as reactive power loading margin of each bus using (4) and (8), respectively.
Minimum out of maximum real power loadability of all the load buses present in the system is considered as
real power loading margin of the system, and corresponding bus was considered as the most critical bus
based on real power loading margin. Minimum out of maximum reactive power loadability of all the load
buses present in the system was considered as reactive power loading margin of the system, and
corresponding bus was considered as the most critical bus based on reactive power loading margin criterion.
A flow chart for finding loading margin as well as most critical bus based on PMU measurements is shown in
Figure 3. Since, loading margin of a real time system keeps on changing with change in operating conditions;
it is proposed to update loading margin as well as most critical bus information based on new PMU
measurements obtained, at regular intervals. Flowchart shown in Figure 3 assumes very high initial loading
margin of 10,000 MW and 10,000 MVAR, respectively, keeping in mind such values to be higher than
loading margin of any of the load buses present in the system, and keeps on reducing these till real power
loading margin as well as reactive power loading margin of the most critical bus are obtained. Pseudo
measurements were performed using following network observability rules:
a. If voltage and current phasor at one end of a branch are known, voltage phasor at the other end of
the branch can be calculated using Ohm’s law.
b. If voltage phasors at both the ends of a branch are known, branch current can be calculated
c. If there exists a zero-injection bus with all branch currents known except for one, the unknown branch
current can be calculated using Kirchhoff’s Current Law (KCL).
3. CASE STUDIES
Proposed approach of online monitoring of voltage stability margin was tested on IEEE 14-bus
system, New England 39-bus system and 246-bus Northern Region Power Grid (NRPG) system of India with
the help of Power System Analysis Toolbox (PSAT) software [24]. Simulation results obtained on three
systems are presented below:
3.1. IEEE 14-Bus System
IEEE 14-bus system consists of two synchronous generators (at bus numbers 1 and 2),
three synchronous condensers (at bus number 3, 6 and 8) and 20 transmission lines including three
transformers [25]. This system has a zero-injection bus at bus number 7. PMUs were placed at bus numbers
2, 4, 5, 6 and 9 based on results of binary integer linear programming [23] ensuring full network
observability even in case of loss of few PMUs. Voltage magnitude, real power demand and reactive power
demand of all the load buses were obtained at three operating points (viz. points 1, 2 and 3, respectively)
using combination of PMU measurements and pseudo measurements for the system intact case. Constants a1i,
a2i and a3i were calculated using (9), (10) and (11) for each of the load buses. Evaluated constants were used
to find nose point real power demand ( i
n
DP ) of each load bus using (4). Minimum out of nose point real
power demand of all the load buses was considered as real power loading margin
xMa
DP of the intact system,
and bus having minimum
i
n
DP value was considered as the most critical bus requiring attention as far as
system real power loadability is concerned. In order to update loading margin information under change in
operating scenario, PMU measurements as well as pseudo measurements obtained at three operating points
under all the single line outage cases were used for evaluation of updated a1i, a2i, a3i for all the load buses, and
new
xMa
DP were calculated under these conditions using flow chart shown in Figure 3.
6. Int J Elec & Comp Eng ISSN: 2088-8708
Online monitoring of voltage stability margin using PMU measurements (Pankaj Sahu)
1161
Figure 3. Flowchart for determining loading margin of system using proposed approach
Measured voltage magnitude and real power demand of the most critical bus at the three operating
points, 𝑃𝐷
𝑀𝑎𝑥
calculated using proposed approach and real power loadability based most critical bus number
have been shown in Table 1 for the system intact case and few critical contingency cases. In order to validate
real power loading margin obtained by proposed approach, real power demand versus voltage magnitude
curve (P-V curve) of most critical bus was plotted using continuation power flow (CPF) method [26] for
the system intact case and all the single line outage cases. For obtaining P-V curve of the most critical bus
using CPF method, its real power demand 𝑃𝐷 𝑗
was varied as per following:
𝑃𝐷𝑗 = 𝑃𝐷 𝑗
1
(1 + 𝜆𝑗𝑝) (15)
where, 𝜆𝑗𝑝= fraction of real power demand increase at bus-j
Real power loading margin (𝑃𝐷
𝑀𝑎𝑥
) of the most critical bus obtained by CPF method (real power
demand at the nose point of its P-V curve) have also been shown in Table 1 for the system intact case
and few critical contingency cases. It is observed from Table 1 that real power loading margin obtained
by proposed approach closely matches with real power loading margin found by continuation power
flow method.
7. ISSN: 2088-8708
Int J Elec & Comp Eng, Vol. 10, No. 2, April 2020 : 1156 - 1168
1162
Table 1. Real power loading margin under critical contingencies (IEEE 14-bus system)
C.C.
M.C.B
(Bus-j)
Point 1 Point 2 Point 3
xMa
DP (MW)
1
jV
(p.u.)
1
jDP
(MW)
2
jV
(p.u.)
2
jDP
(MW)
3
jV
(p.u.)
3
jDP
(MW) P.A. CPF
Intact 5 1.03 7.60 0.96 36.16 0.90 37.09 39.44 40.20
1-2 5 1.03 7.60 0.95 17.71 0.91 16.26 17.78 16.49
2-3 4 1.03 47.8 0.95 177.82 0.90 187.85 189.7 188.3
2-4 5 1.03 7.60 0.96 30.40 0.90 30.86 32.76 32.91
1-5 5 1.02 7.60 0.95 37.32 0.92 34.50 37.39 34.50
2-5 5 1.02 7.60 0.95 33.14 0.90 33.21 35.64 35.26
C.C. = critical contingency, M.C.B. = most critical bus number, P.A. = proposed approach
P-V curve of bus 4 (most critical bus) obtained by proposed quadratic fitting of nose curves using
PMU measurements/pseudo measurements at three operating points as well as continuation power flow based
P-V curve of same bus have been shown in Figure 4 for the outage of line 2-4. It is observed from Figure 4
that nose point real power loadability obtained by proposed approach closely matches with real power
loading margin of the bus obtained by continuation power flow method.
Figure 4. P-V curve of critical bus 5 obtained using proposed approach and by CPF method
for line outage 2-4 (IEEE 14-bus system)
Constants b1i, b2i and b3i were calculated for each of the load buses using (12), (13) and (14) for
the system intact case and all the single line outage cases using PMU measurements/pseudo measurements.
Evaluated constants were utilized to determine nose point reactive power demand, i
n
DQ of each bus using (8).
Minimum out of nose point reactive power demand ( i
n
DQ ) of all the load buses was considered as reactive
power loading margin 𝑄 𝐷
𝑀𝑎𝑥
of the system, and bus having minimum i
n
DQ value was considered as most
critical bus requiring attention as for as reactive power loading margin is concerned. In order to validate
reactive power loading margin obtained by proposed approach, reactive power demand versus voltage
magnitude curve (Q-V curve) of the most critical bus was obtained by CPF method for the system intact case
and all the single line outage cases. For obtaining Q-V curve of the most critical bus using CPF method,
its reactive power demand was varied using:
𝑄 𝐷 𝑗
= 𝑄 𝐷 𝑗
1
(1 + 𝜆𝑗𝑞) (16)
where, 𝜆𝑗𝑞= fraction of reactive power demand increase at bus-j
Measured voltage magnitude and reactive power demand of most critical bus at three operating
points, reactive power loading margin (𝑄 𝐷
𝑀𝑎𝑥
) obtained by proposed approach as well as by CPF method
have been shown in Table 2, for the system intact case and few critical contingency cases. Reactive power
7.6 11.4 15.3 19.2 23.1 27 30.9 34.8
0.8
0.85
0.9
0.95
1
1.05
Active Power P (MW)
V(p.u.)
Proposed Approach
CPF
8. Int J Elec & Comp Eng ISSN: 2088-8708
Online monitoring of voltage stability margin using PMU measurements (Pankaj Sahu)
1163
loadability based most critical bus number has also been shown in Table 2 for all these cases. It is observed
from Table 2 that
xMa
DQ obtained by proposed approach closely matches with
xMa
DQ obtained by
CPF method.
Table 2. Reactive power loading margin under critical contingencies (IEEE 14-bus system)
C.C M.C.B.
(Bus-j)
Point 1 Point 2 Point 3 xMa
DQ (MVAR)
1
jV
(p.u.)
1
jDQ
(MVAR)
2
jV
(p.u.)
2
jDQ
(MVAR)
3
jV
(p.u.)
3
jDQ
(MVAR)
P.A. CPF
Intact 5 1.03 0.32 0.96 3.81 0.90 7.81 0.85 0.86
1-2 5 1.03 0.32 0.95 1.86 0.91 3.42 0.56 0.54
2-3 4 1.03 0.78 0.95 7.25 0.90 15.33 3.10 3.07
6-13 13 1.01 1.16 0.95 3.20 0.91 6.50 5.57 6.04
9-14 14 1.02 1.00 0.96 3.93 0.92 7.26 4.68 5.22
9-10 10 1.02 1.16 0.96 3.49 0.91 6.99 5.64 6.10
C.C. = critical contingency, M.C.B. = most critical bus number, P.A. = proposed approach
Q-V curve of bus 4 (most critical bus) obtained by proposed quadratic curve fitting of nose curves
using PMU measurements/pseudo measurements obtained at three operating points as well as CPF based Q-V
curve of same bus have been shown in Figure 5 for the outage of line 2-3. It is observed from Figure 5 that
nose point reactive power loadability of bus 4 obtained by proposed approach closely matches with CPF
based nose point reactive power demand.
Figure 5. Q-V curve of critical bus 4 obtained using proposed approach and by CPF method
for line outage 2-3 (IEEE 14-bus system)
3.2. New England 39-Bus System
The New England 39-Bus System has 10 generators and 46 transmission lines with 12 zero-injection
buses at bus numbers 1, 2, 5, 6, 9, 10, 11, 13, 14, 17, 19 and 22 [27]. Binary integer linear programming was
used to optimally place PMUs in the system ensuring full network observability even in case of loss of few
PMUs [23]. It results PMU placement at bus numbers 4, 8, 12, 16, 18, 20, 23, 25, 26, 27, 29, 30, 31, 32, 33,
34, 35, 36, 37, 38 and 39.
Real power loading margin 𝑃𝐷
𝑀𝑎𝑥
was calculated as per flow chart shown in Figure 3 for the system
intact case and all the single line outage cases, as in case of IEEE 14-bus system. Measured voltage
magnitude and real power demand of the most critical bus at the three operating points, 𝑃𝐷
𝑀𝑎𝑥
calculated
using proposed approach and real power loadability based most critical bus number have been shown in
Table 3 for the system intact case and few critical contingency cases. In order to validate real power
loadability obtained by proposed approach, real power demand versus voltage magnitude curve (P-V curve)
of most critical bus was plotted using continuation power flow (CPF) method [26] for the system intact case
and all the single line outage cases. For obtaining P-V curve of the most critical bus, its real power
demand was varied as per (15). Real power loading margin ( 𝑃𝐷
𝑀𝑎𝑥
) of the most critical bus obtained by CPF
0.78 1.17 1.56 1.95 2.34 2.73 3.12
0.85
0.9
0.95
1
1.05
Reactive Power Q (MVAR)
V(p.u.)
Proposed Approach
CPF
9. ISSN: 2088-8708
Int J Elec & Comp Eng, Vol. 10, No. 2, April 2020 : 1156 - 1168
1164
method (real power demand at the nose point of its P-V curve) have also been shown in Table 3 for
the system intact case and few critical contingency cases. It is observed from Table 3 that real power loading
margin obtained by proposed approach closely matches with real power loading margin found by
continuation power flow method.
Table 3. Real power loading margin under critical contingencies (New England 39-bus system)
C.C. M.C.B
(Bus-j)
Point 1 Point 2 Point 3 xMa
DP (MW)
1
jV
(p.u.)
1
jDP
(MW)
2
jV
(p.u.)
2
jDP
(MW)
3
jV
(p.u.)
3
jDP
(MW)
P.A. CPF
Intact 29 1.03 283.5 0.96 1227.56 0.90 1360.80 1363.64 1686.83
28-29 29 1.02 283.5 0.95 768.29 0.89 853.34 856.17 989.42
29-38 20 1.00 680 0.97 2380 0.96 2380 2420.8 2380
21-22 23 1.05 247.5 0.95 868.73 0.91 905.85 908.33 930.60
22-35 29 1.03 283.5 0.98 1097.15 0.96 1097.15 1108.49 1099.98
10-32 29 1.03 283.5 0.98 1102.82 0.96 1102.82 1114.16 1102.82
C.C=critical contingency, M.C.B.=most critical bus number, P.A.=proposed approach
P-V curve of bus 20 (most critical bus) obtained by proposed quadratic fitting of nose curves using
PMU measurements/pseudo measurements obtained at three operating points as well as continuation power
flow based P-V curve of same bus have been shown in Figure 6 for the outage of line 29-38. It is observed
from Figure 6 that nose point real power loadability obtained by proposed approach closely matches with real
power loading margin of the bus obtained by continuation power flow method.
Figure 6. P-V curve of critical bus 20 obtained using proposed approach and by CPF method for line outage
29-38 (New England 39-bus system)
Reactive power loading margin (𝑄 𝐷
𝑀𝑎𝑥
) was calculated as per flow chart shown in Figure 3 for
the system intact case and all the single line outage cases, as in case of IEEE 14-bus system. In order to
validate reactive power loading margin obtained by proposed approach, reactive power demand versus
voltage magnitude curve (Q-V curve) of the most critical bus was also obtained by CPF method for
the system intact case and all the single line outage cases. For obtaining Q-V curve of the most critical bus,
its reactive power demand was varied as per (16). Measured voltage magnitude and reactive power demand
of most critical bus at three operating points, reactive power loading margin (𝑄 𝐷
𝑀𝑎𝑥
) obtained by proposed
approach as well as by CPF method have been shown in Table 4, for the system intact case and few critical
contingency cases. Reactive power loadability based most critical bus number has also been shown in
Table 4 for all these cases. It is observed from Table 4 that
xMa
DQ obtained by proposed approach closely
matches with
xMa
DQ obtained by CPF method.
680 1020 1360 1700 2040 2380
0.95
0.955
0.96
0.965
0.97
0.975
0.98
0.985
0.99
0.995
1
Active Power P (MW)
V(p.u.)
Proposed Approach
CPF
10. Int J Elec & Comp Eng ISSN: 2088-8708
Online monitoring of voltage stability margin using PMU measurements (Pankaj Sahu)
1165
Table 4. Reactive power loading margin under critical contingencies (New England 39-bus system)
C.C.
M.C.B.
(Bus-j)
Point 1 Point 2 Point 3
xMa
DQ (MVAR)
1
jV
(p.u.)
1
jDQ
(MVAR)
2
jV
(p.u.)
2
jDQ
(MVAR)
3
jV
(p.u.)
3
jDQ
(MVAR) P.A. CPF
Intact 29 1.03 25.38 0.96 274.74 0.91 609.12 122.08 151.01
28-29 29 1.02 25.38 0.95 171.95 0.89 381.97 76.65 88.58
29-38 20 1.00 20.60 0.97 180.25 0.96 360.50 73.34 72.10
15-16 15 1.02 30.60 0.96 76.50 0.92 153 142.60 168.90
2-25 25 1.03 9.44 0.95 23.60 0.91 47.20 42.10 51.26
10-32 29 1.03 25.38 0.98 246.82 0.96 493.64 99.74 98.73
C.C. = critical contingency, M.C.B. = most critical bus number, P.A. = proposed approach
Q-V curve of bus 29 (most critical bus) obtained by proposed quadratic curve fitting of nose curves
using PMU measurements/pseudo measurements at three operating points as well as CPF based Q-V curve of
same bus have been shown in Figure7 for the outage of line 10-32. It is observed from Figure 7 that nose
point reactive power loadability of bus 29 obtained by proposed approach closely matches with CPF based
nose point reactive power demand.
Figure 7. Q-V curve of critical bus 29 obtained using proposed approach and by CPF method for line outage
10-32 (New England 39-bus system)
3.3. NRPG 246-Bus System
The 246-bus Northern Regional Power Grid (NRPG) system covers power network of seven states
(Jammu and Kashmir, Himachal Pradesh, Punjab, Haryana, Rajasthan, Uttarakhand and Uttar Pradesh) and
two union territories (Chandigarh and New Delhi) of India [28]. It consists of 42 generators, 36 transformers
and 376 transmission lines. It has 15 zero-injection buses at bus numbers 63, 75, 81, 102, 103, 104, 107, 122,
155, 180, 210, 226, 237, 241, and 244. Binary Integer linear Programming was run to optimally place 97
PMUs in the 246-bus NRPG system to ensure complete observability even in case of loss of few PMUs [23].
xMa
DP was calculated for the system as per flow chart shown in Figure 3 for the system intact case and all
the single line outage cases, as in case of IEEE 14-bus system and New England 39-bus system. Measured
voltage magnitude and real power demand of the most critical bus at the three operating points, real power
loadability based most critical bus number and 𝑃𝐷
𝑀𝑎𝑥
calculated using proposed approach have been shown in
Table 5 for the system intact case and few critical contingency cases. In order to validate real power loading
margin obtained by proposed approach, real power demand versus voltage magnitude curve (P-V curve) of
most critical bus was plotted using continuation power flow (CPF) method [26] for the system intact case and
all the single line outage cases. CPF based P-V curve was obtained by varying real power demand at the bus
as per (15). Real power loading margin (𝑃𝐷
𝑀𝑎𝑥
) of the most critical bus obtained by CPF method (real power
demand at the nose point of its P-V curve) have also been shown in Table 5 for the system intact case and
few critical contingency cases. It is observed from Table 5 that real power loading margin obtained by
proposed approach closely matches with real power loading margin found by continuation power flow
method.
25.38 38.07 50.76 63.45 76.14 88.83 101.52
0.95
0.96
0.97
0.98
0.99
1
1.01
1.02
1.03
1.04
Reactive Power Q (MVAR)
V(p.u.)
Proposed Approach
CPF
11. ISSN: 2088-8708
Int J Elec & Comp Eng, Vol. 10, No. 2, April 2020 : 1156 - 1168
1166
P-V curve of bus 174 (most critical bus) obtained by proposed quadratic fitting of nose curves using
PMU measurements/pseudo measurements at three operating points as well as continuation power flow based
P-V curve of same bus have been shown in Figure 8 for the outage of line 194-198. It is observed from
Figure 8 that nose point real power loadability obtained by proposed approach closely matches with real
power loading margin of the bus obtained by continuation power flow method.
𝑄 𝐷
𝑀𝑎𝑥
was calculated for the system intact case and all the single line outage cases, as in case of
IEEE 14-bus system and New England 39-bus system. In order to validate reactive power loading margin
obtained by proposed approach, reactive power demand versus voltage magnitude curve (Q-V curve) of the
most critical bus was also obtained by CPF method for the system intact case and all the single line outage
cases. CPF based Q-V curve was obtained by varying reactive power demand at the bus as per (16).
Measured voltage magnitude and reactive power demand of most critical bus at three operating points,
reactive power loading margin (𝑄 𝐷
𝑀𝑎𝑥
) obtained by proposed approach as well as by CPF method have been
shown in Table 6, for the system intact case and few critical contingency cases. Reactive power loadability
based most critical bus number has also been shown in Table 6 for all these cases. It is observed from Table 6
that
xMa
DQ obtained by proposed approach closely matches with
xMa
DQ obtained by CPF method.
Q-V curve of bus 158 (most critical bus) obtained by proposed quadratic curve fitting of nose curves
using PMU measurements/pseudo measurements at three operating points as well as CPF based Q-V curve of
same bus have been shown in Figure9 for the outage of line 156-158. It is observed from Figure 9 that nose
point reactive power loadability of bus 158 obtained by proposed approach closely matches with CPF based
nose point reactive power demand.
Table 5. Real power loading margin under critical contingencies (NRPG 246-bus system)
C.C. M.C.B.
(Bus-j)
Point 1 Point 2 Point 3 xMa
DP
(MW)
1
jV
(p.u.)
1
jDP
(MW)
2
jV
(p.u.)
2
jDP
(MW)
3
jV
(p.u.)
3
jDP
(MW)
P.A.
CPF
Intact 174 1.01 169.8 0.95 419.41 0.90 485.63 487.33 641.84
173-174 174 1.01 169.8 0.96 249.61 0.90 264.89 269.98 344.69
40-41 174 1.01 169.8 0.96 382.05 0.94 384.35 388.84 383.75
166-173 174 1.01 169.8 0.95 339.60 0.90 383.70 385.45 434.69
156-158 158 1.01 174.7 0.97 468.20 0.96 459.46 473.44 476.93
194-198 174 1.01 174.7 0.95 468.20 0.90 459.46 506.63 518.86
C.C=critical contingency, M.C.B.=most critical bus number, P.A.=proposed approach
Figure 8. P-V curve of critical bus 174 obtained using proposed approach and by CPF method
for line outage 194-198 (NRPG 246-bus system)
174.7 208.8 244.58 279.52 314.46 349.4 384.34 419.28 454.22 489.16 524.1
0.85
0.9
0.95
1
1.05
Active Power P (MW)
V(p.u.)
Proposed Approach
CPF
12. Int J Elec & Comp Eng ISSN: 2088-8708
Online monitoring of voltage stability margin using PMU measurements (Pankaj Sahu)
1167
Figure 9. Q-V curve of critical bus 158 obtained using proposed approach and by CPF method
for line outage 156-158 (NRPG 246-bus system)
Table 6. Reactive power loading margin under critical contingencies (NRPG 246-bus system)
C.C.
M.C.B.
(Bus-j)
Point 1 Point 2 Point 3
xMa
DQ
(MVAR)
1
jV
(p.u.)
1
jDQ
(MVAR)
2
jV
(p.u.)
2
jDQ
(MVAR)
3
jV
(p.u.)
3
jDQ
(MVAR) P.A. CPF
Intact 174 1.01 13.52 0.95 83.49 0.90 193.34 38.80 51.11
173-174 174 1.01 13.52 0.96 49.69 0.90 105.46 21.50 27.45
40-41 174 1.01 13.52 0.96 76.05 0.94 151.42 30.96 30.56
166-173 174 1.01 13.52 0.95 67.6 0.90 152.8 30.69 34.61
156-158 158 1.01 12.48 0.97 50.86 0.96 164.11 33.82 34.07
63-70 156 1.01 17.74 1.01 44.35 1.01 88.7 19.51 19.33
C.C. = critical contingency, M.C.B. = most critical bus number, P.A. = proposed approach
4. CONCLUSION
Online monitoring of voltage stability margin using PMU measurements has been proposed in this
work. Proposed approach estimates voltage stability margin based on measurements obtained at three
operating points. Due to highly dynamic nature of power systems, voltage stability margin keeps on
changing. Therefore, proposed approach suggests computation of updated voltage stability margin at regular
intervals based on new PMU measurements obtained. Change in operating scenario has been simulated in
PSAT software considering different single line outage cases. Accuracy of proposed approach has been
validated by comparing voltage stability margin obtained by proposed approach with margin estimated
using continuation power flow method under same set of operating conditions. Case studies performed on
three test systems show that real power loading margin as well as reactive power loading margin of
the system obtained by proposed approach closely matches with loading margin obtained by continuation
power flow method.
REFERENCES
[1] C. W. Taylor, Power system voltage stability, New York: Mc Graw Hill, 1994.
[2] P. Kundur, Power system stability and control, New York: Mc Graw Hill, 1994.
[3] V. Ajjarapu and B. Lee, “Bibliography on Voltage Stability,” IEEE Trans. on Power Systems, pp. 115-125, vol. 13,
no. 1, Feb 1998.
[4] Antonio C. Zambroni de Souza et al, “On-Line Voltage Stability Monitoring,” IEEE Trans. on Power Systems,
pp. 1300-1305, vol. 15, no. 4, Nov 2000.
[5] Bruno Leonardi and Venkataramana Ajjarapu, “Development of Multi Linear Regression Models for Online
Voltage Stability Margin Estimation,” IEEE Trans. on Power Systems, pp. 374-383, vol. 26, no. 1, Feb 2011.
[6] Yiwei Qiu, Hao Wu, Yongzhi Zhou and Yonghua Song, “Global Parametric Polynomial Approximation of Static
Voltage Stability Region Boundaries,” IEEE Trans. on Power Systems, pp. 2362-2371, vol. 32, no. 3, May 2017.
[7] M. Glavic and T. Van Cutsem, “Wide-Area Detection of Voltage Instability from Synchronized Phasor
Measurements, Part I: Principle,” IEEE Trans. on Power Systems, pp. 1408-1416, vol. 24, no. 2, May 2009.
12.48 14.98 17.47 19.97 22.46 24.96 27.46 29.95 32.45 34.94
0.9
0.92
0.94
0.96
0.98
1
1.02
Reactive Power Q (MVAR)
V(p.u.)
Proposed Approach
CPF
13. ISSN: 2088-8708
Int J Elec & Comp Eng, Vol. 10, No. 2, April 2020 : 1156 - 1168
1168
[8] F. Aminifar et al, “Synchrophasor Measurement Technology in Power Systems: Panorama and State-of-the-art”
IEEE Access, pp. 1607-1628, vol. 2, 2014.
[9] K. Vu et. al., “Use of Local Measurements to Estimate Voltage Stability Margin,” IEEE Trans. on Power Systems,
vol. 14, no. 3, pp. 1029-1035, Aug 1999.
[10] I. Simen, G. Verbic and P. Gubina, “Local Voltage Stability Index using Tellegen’s Theorem,” IEEE Trans. on
Power Systems, vol. 21, no. 3, pp. 1267-1275, Aug 2006.
[11] H. Y. Su and C. W. Liu, “Estimating of Voltage Stability Margin using PMU Measurements,” IEEE Trans. on
Power Systems, vol. 31, no. 4, pp. 3221-3229, Jul 2016.
[12] Costas D. Vournas, Charalambos Lambrou and Panagiotis Mandoulidis, “Voltage Stability Monitoring From a
Transmission Bus PMU,” IEEE Trans. on Power Systems, vol. 32, no. 4, pp. 3266-3274, Jul 2017.
[13] P. Zhang, L. Min and J. Chen, “Measurement-based Voltage Stability Monitoring and Control,” U.S. Patent 8.126
667, 2012.
[14] K. Sun, P. Zhang and L. Min, “Measurement-based Voltage Stability Monitoring and Control for Load Centers,”
EPRI Report No. 1017798, 2009.
[15] Fengkai Hu et al, “Measurement Based Real-Time Voltage Stability Monitoring for Load Areas,” IEEE Trans. on
Power Systems, vol. 31, no. 4, pp. 2787-2798, Jul 2016.
[16] John William Simpson-Porco and Francesco Bullo, “Distributed Monitoring of Voltage Collapse Sensitivity
Indices,” IEEE Trans. on Smart Grid, vol. 7, no. 4, pp. 1979-1988, Jul 2016.
[17] Haoen Li, Anjan Bose and V. Venkatasubramanian, “Wide-Area Monitoring and Optimization,” IEEE Trans. on
Smart Grid, vol. 7, no. 2, pp. 785-793, Mar 2016.
[18] Mariana Kamel, Abdelrahman A. Karrar and Ahmed H. Eltom, “Development and Application of a New Voltage
stability Index for On-Line Monitoring and Shedding,” IEEE Trans. on Power Systems, vol. 33, no. 2,
pp. 1231-1241, Mar 2018.
[19] Debbie Q. Zhou, Udaya D. Annakkage and Athula D. Rajapakse, “Online Monitoring of Voltage Stability Margin
using an Artificial Neural Network,” IEEE PES General Meeting, USA, 25-29 Jul 2010.
[20] Heng–Yi Su and Tzu-Yi Liu, “Enhanced-Online-Random-Forcast Model for Static Voltage Stability Assessment
Using Wide Area Measurements,” IEEE Trans. on Power Systems, vol. 33, no. 6, pp. 6696-6704, Nov 2018.
[21] E. Gonzaled et. al., “PMU based Voltage Stability Indices with Intermediate Load Corrections,” IEEE Latin
America Trans. vol. 16, no. 4, pp. 1172-1179, Apr 2018.
[22] Samuel C. Chevalier and Paul D. H. Hines, “Mitigating the Risk of Voltage Collapse Using Statistical Measures
from PMU Data,” IEEE Trans. on Power Systems, vol. 34, no. 1, pp. 120-128, Jan 2019.
[23] Pankaj Sahu and M. K. Verma, "Optimal Placement of PMUs in Power System Network for Voltage Stability
Estimation under Contingencies,” 6th IEEE International Conference on Computer Applications in Electrical
Engineering-Recent Advances (CERA), Roorkee, India, pp. 365-370, 5-7 Oct 2017.
[24] PSAT Software Manual, [Online]. Available: http://faraday1.ucd.ie/psat.html.
[25] IEEE 14-Bus System, [Online]. Available: http://www.ee.washington.edu/research/pstca/pf14/pg_tca14bus.htm].
[26] V. Ajjarapu and C. Christy, “The Continuation Power Flow: A Tool for Steady State Voltage Stability Analysis,”
IEEE Trans. on Power Systems, vol. 7, no. 1, pp. 416-423, Feb 1992.
[27] New England 39-Bus System [Online]. Available: http://icseg.iti.illinois.edu/ieee-39-bus-system/]
[28] North Region Power Grid (NRPG) 246-Bus System; 2013 [Online]. Available:
http://www.iitk.ac.in/eeold/facilities/Research_labs/Power_System/NRPG-DATA.pdf].
BIOGRAPHIES OF AUTHORS
Pankaj Sahu received his B.Tech degree in electrical engineering from Harcourt Butler
Technological Institute, Kanpur, India in 2007 and M.Tech degree in electrical engineering from
Motilal Nehru National Institute of Technology, Allahabad, India in 2010. He is currently
persuing for PhD degree at Indian Institute of Technology (BHU), Varanasi, India. His research
interests include control system, instrumentation and voltage stability studies.
M. K. Verma received his B.Sc (Eng.) degree in electrical engineering from Regional
Engineering College, Rourkela (presently National Institute of Technology, Rourkela), India in
1989, M.Sc (Eng.) degree in electrical engineering from Bihar Institute of Technology, Sindri,
India in 1994 and PhD degree in electrical engineering from Indian Institute of Technology (IIT),
Kanpur, India in 2005. He is currently working as Professor in electrical engineering department
at Indian Institute of Technology (BHU), Varanasi, India. His current research interests include
voltage stability studies, application of FACTS controllers, power quality, wide area monitoring
system and smart grid