1) The document analyzes errors in distance relay readings with the presence of FACTS devices like STATCOM and SSSC.
2) It presents models of SSSC and STATCOM and studies their impact on the measured impedance seen by the distance relay for single line to ground faults.
3) The analysis shows how the measured impedance, and the ideal tripping characteristic of the distance relay, are affected by the location and operational conditions of FACTS devices.
Distance Algorithm for Transmission Line with Mid-Point Connected STATCOMIRJET Journal
This document presents an adaptive zone selection algorithm for distance protection of a transmission line with a midpoint connected STATCOM device. The algorithm aims to address challenges to distance protection posed by the presence of the STATCOM. It investigates the impact of the STATCOM on apparent impedance seen by distance relays under different fault conditions using EMTDC/PSCAD software. An adaptive setting is proposed that calculates a new reach based on system and STATCOM parameters to ensure proper operation of distance relays for both underreach and overreach scenarios. The performance of the proposed adaptive algorithm is evaluated through simulations of various single line to ground and three phase fault cases with different fault locations, resistances and system load angles.
Efficiency, reliability, high power quality and continuous operation are important aspects in electric vehicle attraction system. Therefore, quick fault detection, isolation and enhanced fault-tolerant control for open-switches faults in inverter driving systems become more and more required in this filed. However, fault detection and localization algorithms have been known to have many performance limitations due to speed variations such as wrong decision making of fault occurrence. Those weaknesses are investigated and solved in this paper using currents magnitudes fault indices, current direct component fault indices and a decision system. A simulation model and experimental setup are utilized to validate the proposed concept. Many simulation and experimental results are carried out to show the effectiveness of the proposed fault detection approach.
This paper presents an analytical comparison between two-level inverter and three-level neutral point diode clamped inverters for electric vehicle traction purposes. The main objective of the research is to declare the main differences in the performance of the two inverter schemes in terms of the switching and conduction losses over an entire domain of the modulation index and the phase angle distribution, steady-state operation, transient operation at a wide range of speed variation, and the total harmonic distortion THD% of the line voltage output waveform. It also declares the analysis of the three-level neutral point diode clamped inverter (NPCI) obstacle and the unbalance of the DC-link capacitor voltages. The introduced scheme presents an Induction Motor (IM) drive for electric vehicle (EV) applications. Considering the dynamic operation of the EV, the speed of the three-phase induction motor is controlled using a scalar V/Hz control for the full range of the IM power factor (PF). A comprehensive MATLAB/Simulink model for the proposed scheme is established.
Permanent Fault Location in Distribution System Using Phasor Measurement Unit...IJECEIAES
This paper proposes a new method for locating high impedance fault in distribution systems using phasor measurement units (PMUs) installed at certain locations of the system. To implement this algorithm, at first a new method is suggested for the placement of PMUs. Taking information from the units, voltage and current of the entire distribution system are calculated. Then, the two buses in which the fault has been occurred is determined, and location and type of the fault are identified. The main characteristics of the proposed method are: the use of distributed parameter line model in phase domain, considering the presence of literals, and high precision in calculating the high impedance fault location. The results obtained from simulations in EMTP-RV and MATLAB software indicate high accuracy and independence of the proposed method from the fault type, fault location and fault resistance compared to previous methods, so that the maximum observed error was less than 0.15%.
POWER SYSTEM SIMULATION LAB-1 MANUAL (ELECTRICAL - POWER SYSTEM ENGINEERING )Mathankumar S
This document discusses the computation of parameters for single and double circuit transmission lines. It provides the theoretical background on line parameters such as resistance, inductance, capacitance. Formulas are given for calculating inductance and capacitance based on the geometric mean distance and radius for different conductor arrangements including single circuit, three phase symmetrical, asymmetrical transposed lines and double circuit transposed lines. Sample exercises are given to calculate the inductance and capacitance of given transmission line configurations and verify the results using software.
Power System Modelling And Simulation LabSachin Airan
This document is a lab manual for a Power System Modeling and Simulation course. It provides instructions on how to simulate synchronous machines using MATLAB software. The first experiment introduces the swing equation, which models the dynamics of a synchronous generator's rotor motion. The second experiment describes how to model a synchronous machine in Simulink, including defining its electrical and mechanical parameters. The manual lists the synchronous machine model's equations and parameters that must be specified in the Simulink model block.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
Power Circuits and Transforers-Unit 1 Labvolt Student Manualphase3-120A
This document discusses fundamentals of electrical circuits, including basic concepts, symbols, and terminology. It covers topics like voltage, current, resistance, and Ohm's law. The document contains detailed information and diagrams about atomic structure, electric fields, resistance of materials, and measuring voltage and current using a data acquisition system. It provides objectives and procedures for an exercise to demonstrate and apply Ohm's law using circuit measurements.
Distance Algorithm for Transmission Line with Mid-Point Connected STATCOMIRJET Journal
This document presents an adaptive zone selection algorithm for distance protection of a transmission line with a midpoint connected STATCOM device. The algorithm aims to address challenges to distance protection posed by the presence of the STATCOM. It investigates the impact of the STATCOM on apparent impedance seen by distance relays under different fault conditions using EMTDC/PSCAD software. An adaptive setting is proposed that calculates a new reach based on system and STATCOM parameters to ensure proper operation of distance relays for both underreach and overreach scenarios. The performance of the proposed adaptive algorithm is evaluated through simulations of various single line to ground and three phase fault cases with different fault locations, resistances and system load angles.
Efficiency, reliability, high power quality and continuous operation are important aspects in electric vehicle attraction system. Therefore, quick fault detection, isolation and enhanced fault-tolerant control for open-switches faults in inverter driving systems become more and more required in this filed. However, fault detection and localization algorithms have been known to have many performance limitations due to speed variations such as wrong decision making of fault occurrence. Those weaknesses are investigated and solved in this paper using currents magnitudes fault indices, current direct component fault indices and a decision system. A simulation model and experimental setup are utilized to validate the proposed concept. Many simulation and experimental results are carried out to show the effectiveness of the proposed fault detection approach.
This paper presents an analytical comparison between two-level inverter and three-level neutral point diode clamped inverters for electric vehicle traction purposes. The main objective of the research is to declare the main differences in the performance of the two inverter schemes in terms of the switching and conduction losses over an entire domain of the modulation index and the phase angle distribution, steady-state operation, transient operation at a wide range of speed variation, and the total harmonic distortion THD% of the line voltage output waveform. It also declares the analysis of the three-level neutral point diode clamped inverter (NPCI) obstacle and the unbalance of the DC-link capacitor voltages. The introduced scheme presents an Induction Motor (IM) drive for electric vehicle (EV) applications. Considering the dynamic operation of the EV, the speed of the three-phase induction motor is controlled using a scalar V/Hz control for the full range of the IM power factor (PF). A comprehensive MATLAB/Simulink model for the proposed scheme is established.
Permanent Fault Location in Distribution System Using Phasor Measurement Unit...IJECEIAES
This paper proposes a new method for locating high impedance fault in distribution systems using phasor measurement units (PMUs) installed at certain locations of the system. To implement this algorithm, at first a new method is suggested for the placement of PMUs. Taking information from the units, voltage and current of the entire distribution system are calculated. Then, the two buses in which the fault has been occurred is determined, and location and type of the fault are identified. The main characteristics of the proposed method are: the use of distributed parameter line model in phase domain, considering the presence of literals, and high precision in calculating the high impedance fault location. The results obtained from simulations in EMTP-RV and MATLAB software indicate high accuracy and independence of the proposed method from the fault type, fault location and fault resistance compared to previous methods, so that the maximum observed error was less than 0.15%.
POWER SYSTEM SIMULATION LAB-1 MANUAL (ELECTRICAL - POWER SYSTEM ENGINEERING )Mathankumar S
This document discusses the computation of parameters for single and double circuit transmission lines. It provides the theoretical background on line parameters such as resistance, inductance, capacitance. Formulas are given for calculating inductance and capacitance based on the geometric mean distance and radius for different conductor arrangements including single circuit, three phase symmetrical, asymmetrical transposed lines and double circuit transposed lines. Sample exercises are given to calculate the inductance and capacitance of given transmission line configurations and verify the results using software.
Power System Modelling And Simulation LabSachin Airan
This document is a lab manual for a Power System Modeling and Simulation course. It provides instructions on how to simulate synchronous machines using MATLAB software. The first experiment introduces the swing equation, which models the dynamics of a synchronous generator's rotor motion. The second experiment describes how to model a synchronous machine in Simulink, including defining its electrical and mechanical parameters. The manual lists the synchronous machine model's equations and parameters that must be specified in the Simulink model block.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
Power Circuits and Transforers-Unit 1 Labvolt Student Manualphase3-120A
This document discusses fundamentals of electrical circuits, including basic concepts, symbols, and terminology. It covers topics like voltage, current, resistance, and Ohm's law. The document contains detailed information and diagrams about atomic structure, electric fields, resistance of materials, and measuring voltage and current using a data acquisition system. It provides objectives and procedures for an exercise to demonstrate and apply Ohm's law using circuit measurements.
The study made in this paper concerns the use of the voltage-oriented control (VOC) of three-phase pulse width modulation (PWM) rectifier with constant switching frequency. This control method, called voltage-oriented controlwith space vector modulation (VOC-SVM). The proposed control scheme has been founded on the transformation between stationary (α-β) and and synchronously rotating (d-q) coordinate system, it is based on two cascaded control loops so that a fast inner loop controls the grid current and an external loop DC-link voltage, while the DC-bus voltage is maintained at the desired level and ansured the unity power factor operation. So, the stable state performance and robustness against the load’s disturbance of PWM rectifiers are boths improved. The proposed scheme has been implemented and simulated in MATLAB/Simulink environment. The control system of the VOC-SVM strategy has been built based on dSPACE system with DS1104 controller board. The results obtained show the validity of the model and its control method. Compared with the conventional SPWM method, the VOC-SVM ensures high performance and fast transient response.
The transmission overhead line is one of the vital elements in the power system for transmitting the electrical energy. In the transmission, the disturbances are often occurred. In the conventional algorithm, alpha and beta (mode) currents generated by Clarke’s transformation are utilized to convert the signal of Discrete Wavelet Transform (DWT) to obtain the Wavelet Transform Coefficient (WTC) and the Wavelet Coefficient Energy (WCE). This study introduces a new algorithm, called Modified Clarke for fault detection and classification using DWT and Back-Propagation Neural Network (BPNN) based on Clarke’s transformation on transmission overhead line by adding gamma current in the system. Daubechies4 (Db4) is used as a mother wavelet to decompose the high frequency components of the signal error. Simulation is performed using PSCAD / EMTDC transmission system modeling and carried out at different locations along the transmission line with different types of fault, fault resistances, fault locations and fault of the initial angle on a given power system model. The simulated fault types are in the study are the Single Line to Ground, the Line To Line, the Double Line to Ground and the Three Phases. There are four statistic methods utilized in the present study to determine the accuracy of detection and classification of faults. The result shows that the best and the worst structures of BPNN occurred on the configuration of 12-24-48-4 and 12-12-6-4, respectively. For instance, the error using Mean Square Error Method. The Error Of Clarke’s, Without Clarke’s and Modified Clarke’s are 0.05862, 0.05513 and 0.03721 which are the best, respectively, whereas, the worst are 0.06387, 0.0753 and 0.052, respectively. This indicates that the Modified Clarke’s result is in the lowest error. The method is successfully implement can be utilized in the detection and classification of fault in transmission line by utilities and power regulation in power system planning and operation.
This document describes a method for solving voltage stability problems in electrical power systems using Field Programmable Gate Array (FPGA) circuits. The modal analysis method and Q-V curves are used to analyze voltage stability and identify weak buses. Two Spartan 3 FPGAs are used - one to receive power system data from a computer and the other to transmit data to network components to implement reactive power corrections online using wireless communication. The method is demonstrated on the 9-bus WSCC test system, where bus 5 is identified as the weakest bus. Q-V curves confirm this and show stability margins increase after compensation is applied through the FPGA system.
The document is about power system analysis and contains the following information:
1. It discusses the advantages of per unit computation such as manufacturers specifying impedance in per unit values and impedances being within a narrow range even for widely different ratings.
2. It asks questions related to load flow analysis, types of buses, Jacobian matrix, need for slack bus, and static load flow equations.
3. It covers topics like power flow solution methods, representation of loads, need for base values, and applications of bus admittance matrix in load flow analysis.
Carrier based hybrid pwm algorithm with reduced common mode voltageIAEME Publication
This document proposes a hybrid PWM algorithm to reduce common mode voltage variations in three-phase voltage source inverter fed induction motor drives. It presents a carrier-based approach to generate active zero state PWM techniques through addition of a zero sequence voltage. To further reduce harmonic distortion, a hybrid PWM technique is presented based on analysis of stator flux ripple. Simulation results on a v/f controlled induction motor drive show that the proposed algorithm minimizes common mode voltage variations compared to the space vector PWM algorithm.
This document summarizes a research paper on minimizing total harmonic distortion (THD) in a three-phase, five-level cascaded H-bridge inverter. It first describes the configuration and operation of a cascaded H-bridge multilevel inverter. It then reviews the generalized formulation of selective harmonic elimination (SHE) for multilevel inverters. The document presents a MATLAB/Simulink model of a three-phase, five-level inverter that compares sinusoidal pulse width modulation to SHE for harmonic reduction. Simulation results show that SHE reduces THD from 71.2% to 4.66% by eliminating specific lower-order harmonics through optimization of the switching angles.
Three-Level DTC Based on Fuzzy Logic and Neural Network of Sensorless DSSM Us...IJPEDS-IAES
This paper presents a direct torque control is applied for salient-pole double star synchronous machine without mechanical speed and stator flux linkage sensors. The estimation is performed using the extended Kalman filter known by it is ability to process noisy discrete measurements. Two control approaches using fuzzy logic DTC, and neural network DTC are proposed and compared. The validity of the proposed controls scheme is verified by simulation tests of a double star synchronous machine. The stator flux, torque, and speed are determined and compared in the above techniques. Simulation results presented in this paper highlight the improvements produced by the proposed control method based on the extended Kalman filter under various operation conditions.
This document presents a comparative study of five-level and seven-level diode-clamped inverters controlled by space vector pulse width modulation (SVPWM). MATLAB/SIMULINK models of the two inverter topologies were developed. SVPWM control algorithms based on symmetrical sequence were used for each inverter. Both inverters were simulated driving an induction motor. The results showed that the seven-level inverter produced less harmonic distortion and torque fluctuations in the motor, while the five-level inverter had lower commutation losses. The seven-level inverter provided better motor dynamic response.
Sharing of the Output Current of A Voltage Source Inverter between Controlled...IDES Editor
When a two level VSI feeds an induction motor, the
motor current is almost sinusoidal though the voltages at the
terminals have substantial high frequency harmonics. Further
the load current is shared between the controlled switch and
the antiparallel diodes .These essential features of a two level
VSI are studied in this paper using MATLAB simulation.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Improvement the voltage stability margin of Iraqi power system using the opti...IJECEIAES
The detection of potential voltage collapse in power systems is essential to maintain the voltage stability in heavy load demand. This paper proposes a method to detect weak buses in power systems using two stability indices: the voltage stability margin factor (dS/dY) and the voltage collapse prediction index (VCPI). Hence, the paper aims to improve the voltage stability of Iraqi transmission grid by allocating FACTS devices in the optimal locations and optimal sizes. Two types of FACTS are used in this paper which are Thyristor controlled series compensator (TCSC) and static var compensator (SVC). The objective function of the problem is fitted using particle swarm optimization (PSO). The proposed method is verified using simulation test on Diyala-132 kV network which is a part of the Iraqi power system. The results observed that improvement the voltage stability margin, the voltage profile of Diyala-132 kV is increased and the power losses is decreased.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
This document summarizes a research paper that proposes three direct torque control (DTC) strategies for brushless DC motors fed by a four-switch inverter (B4-inverter) to reduce torque ripple. It first reviews the operation of BLDC motors with six-switch (B6-inverter) and B4-inverters, including two-phase and three-phase conduction modes. It then describes three DTC strategies: DTC-1 adapted from B6-inverter control, DTC-2 with a vector selection table to independently control phase torques, and proposed DTC-3 to eliminate torque dips of DTC-2 during sector transitions. Experimental results show DTC-
This document provides instructions for connecting the windings of a three-phase transformer in delta-delta and wye-wye configurations. It describes verifying the phase relationships by measuring voltages before closing the secondary windings. For a delta connection, the voltage within the closed delta must be zero to avoid high currents. The procedure involves connecting the transformer, measuring voltages to check phase relationships, closing the secondary delta if voltages are correct, and measuring secondary line voltages.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
The document provides an overview of the SimPowerSystems library in Simulink, which contains blocks for modeling and simulating electrical power systems. It contains nine sublibraries for modeling various electrical components including sources, elements, transformers, breakers, lines, power electronics, machines, measurements and control blocks. The SimPowerSystems library allows modeling and simulation of electrical circuits, electrical machines, drives, static converters and complete power energy systems. It can be used to model and analyze power systems and their dynamic behavior.
Speed Control System for BLDC Motor by using Direct Back EMF Detection Mathodijtsrd
BLDC motors are used in many industrial and traction applications due to high efficiency, low maintenance and high torque. For good performance of BLDC motors, the accurate knowledge of the rotor position is required. The need for the rotor position information in BLDC motors have been satisfied by use of some form of rotor position sensors. But to reduce cost, complexity and also to improve reliability of the system, sensor less drive system is preferred. In this paper, the development of sensor less control system for BLDC motor using a direct back EMF detection method is presented and simulation for proposed system is done with the help of MATLAB SIMULINK. Soe Sandar Aung | Thet Naing Htun "Speed Control System for BLDC Motor by using Direct Back EMF Detection Mathod" 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/ijtsrd26624.pdfPaper URL: https://www.ijtsrd.com/engineering/electrical-engineering/26624/speed-control-system-for-bldc-motor-by-using-direct-back-emf-detection-mathod/soe-sandar-aung
Power Circuits and Transforers-Unit 8 Labvolt Student Manualphase3-120A
This exercise explores connecting transformers in parallel and measuring their efficiency. Two 100-VA transformers are connected in parallel to supply a 200-VA load. Efficiency is calculated as the ratio of output power to input power. Measurements of input and output power will be taken to determine the overall efficiency and verify that the load is shared between the two transformers. Connecting transformers in parallel allows supplying power greater than the rating of a single transformer.
Application of SVM Technique for Three Phase Three Leg Ac/Ac Converter TopologyIOSR Journals
This paper presents a simulation of a three-phase three-leg AC/AC converter topology using nine IGBTs and space vector pulse width modulation (SVM) technique. The proposed topology reduces the number of switches compared to conventional back-to-back and matrix converters. Simulation results show the converter provides sinusoidal input and output voltages with unity power factor under constant frequency and variable frequency operation. Experimental results from a 5kVA prototype verify the validity of the proposed scheme.
A Study of SVC’s Impact Simulation and Analysis for Distance Protection Relay...IJECEIAES
This paper focuses on analyzing and evaluating impact of a Static Var Compensator (SVC) on the measured impedance at distance protection relay location on power transmission lines. The measured impedance at the relay location when a fault occurs on the line is determined by using voltage and current signals from voltage and current transformers at the relay and the type of fault occurred on the line. The MHO characteristic is applied to analyze impact of SVC on the distance protection relay. Based on the theory, the authors in this paper develop a simulation program on Matlab/Simulink software to analyze impact of SVC on the distance protection relay. In the power system model, it is supposed that the SVC is located at mid-point of the transmission line to study impact of SVC on the distance relay. The simulation results show that SVC will impact on the measured impedance at the relay when the fault occurs after the location of the SVC on the power transmission line.
The document discusses reactive power compensation using a STATCOM. It describes various compensation schemes including shunt capacitors, synchronous condensers, SVCs, and STATCOMs. STATCOMs offer fast response times and can compensate for both lagging and leading reactive power. The document then examines the operating principle, control strategies using variable voltage and phase angle control, simulation circuits, reactive power calculations, voltage and current waveforms, and proposed control strategies for STATCOMs, including decoupling Id and Iq currents to improve system response and stability.
Statcom control scheme for power quality improvement of grid connected wind e...Kinnera Kin
This project aims to improve power quality for a grid-connected wind energy system using a STATCOM. The objectives are to maintain unity power factor at the source, meet reactive power needs of the wind generator and non-linear load, and provide fast response using hysteresis current control for the STATCOM. MATLAB/Simulink software is used to simulate the system both with and without STATCOM. The simulation results show that with STATCOM, harmonic distortion is eliminated in the load current and power quality is maintained at the point of common coupling.
The study made in this paper concerns the use of the voltage-oriented control (VOC) of three-phase pulse width modulation (PWM) rectifier with constant switching frequency. This control method, called voltage-oriented controlwith space vector modulation (VOC-SVM). The proposed control scheme has been founded on the transformation between stationary (α-β) and and synchronously rotating (d-q) coordinate system, it is based on two cascaded control loops so that a fast inner loop controls the grid current and an external loop DC-link voltage, while the DC-bus voltage is maintained at the desired level and ansured the unity power factor operation. So, the stable state performance and robustness against the load’s disturbance of PWM rectifiers are boths improved. The proposed scheme has been implemented and simulated in MATLAB/Simulink environment. The control system of the VOC-SVM strategy has been built based on dSPACE system with DS1104 controller board. The results obtained show the validity of the model and its control method. Compared with the conventional SPWM method, the VOC-SVM ensures high performance and fast transient response.
The transmission overhead line is one of the vital elements in the power system for transmitting the electrical energy. In the transmission, the disturbances are often occurred. In the conventional algorithm, alpha and beta (mode) currents generated by Clarke’s transformation are utilized to convert the signal of Discrete Wavelet Transform (DWT) to obtain the Wavelet Transform Coefficient (WTC) and the Wavelet Coefficient Energy (WCE). This study introduces a new algorithm, called Modified Clarke for fault detection and classification using DWT and Back-Propagation Neural Network (BPNN) based on Clarke’s transformation on transmission overhead line by adding gamma current in the system. Daubechies4 (Db4) is used as a mother wavelet to decompose the high frequency components of the signal error. Simulation is performed using PSCAD / EMTDC transmission system modeling and carried out at different locations along the transmission line with different types of fault, fault resistances, fault locations and fault of the initial angle on a given power system model. The simulated fault types are in the study are the Single Line to Ground, the Line To Line, the Double Line to Ground and the Three Phases. There are four statistic methods utilized in the present study to determine the accuracy of detection and classification of faults. The result shows that the best and the worst structures of BPNN occurred on the configuration of 12-24-48-4 and 12-12-6-4, respectively. For instance, the error using Mean Square Error Method. The Error Of Clarke’s, Without Clarke’s and Modified Clarke’s are 0.05862, 0.05513 and 0.03721 which are the best, respectively, whereas, the worst are 0.06387, 0.0753 and 0.052, respectively. This indicates that the Modified Clarke’s result is in the lowest error. The method is successfully implement can be utilized in the detection and classification of fault in transmission line by utilities and power regulation in power system planning and operation.
This document describes a method for solving voltage stability problems in electrical power systems using Field Programmable Gate Array (FPGA) circuits. The modal analysis method and Q-V curves are used to analyze voltage stability and identify weak buses. Two Spartan 3 FPGAs are used - one to receive power system data from a computer and the other to transmit data to network components to implement reactive power corrections online using wireless communication. The method is demonstrated on the 9-bus WSCC test system, where bus 5 is identified as the weakest bus. Q-V curves confirm this and show stability margins increase after compensation is applied through the FPGA system.
The document is about power system analysis and contains the following information:
1. It discusses the advantages of per unit computation such as manufacturers specifying impedance in per unit values and impedances being within a narrow range even for widely different ratings.
2. It asks questions related to load flow analysis, types of buses, Jacobian matrix, need for slack bus, and static load flow equations.
3. It covers topics like power flow solution methods, representation of loads, need for base values, and applications of bus admittance matrix in load flow analysis.
Carrier based hybrid pwm algorithm with reduced common mode voltageIAEME Publication
This document proposes a hybrid PWM algorithm to reduce common mode voltage variations in three-phase voltage source inverter fed induction motor drives. It presents a carrier-based approach to generate active zero state PWM techniques through addition of a zero sequence voltage. To further reduce harmonic distortion, a hybrid PWM technique is presented based on analysis of stator flux ripple. Simulation results on a v/f controlled induction motor drive show that the proposed algorithm minimizes common mode voltage variations compared to the space vector PWM algorithm.
This document summarizes a research paper on minimizing total harmonic distortion (THD) in a three-phase, five-level cascaded H-bridge inverter. It first describes the configuration and operation of a cascaded H-bridge multilevel inverter. It then reviews the generalized formulation of selective harmonic elimination (SHE) for multilevel inverters. The document presents a MATLAB/Simulink model of a three-phase, five-level inverter that compares sinusoidal pulse width modulation to SHE for harmonic reduction. Simulation results show that SHE reduces THD from 71.2% to 4.66% by eliminating specific lower-order harmonics through optimization of the switching angles.
Three-Level DTC Based on Fuzzy Logic and Neural Network of Sensorless DSSM Us...IJPEDS-IAES
This paper presents a direct torque control is applied for salient-pole double star synchronous machine without mechanical speed and stator flux linkage sensors. The estimation is performed using the extended Kalman filter known by it is ability to process noisy discrete measurements. Two control approaches using fuzzy logic DTC, and neural network DTC are proposed and compared. The validity of the proposed controls scheme is verified by simulation tests of a double star synchronous machine. The stator flux, torque, and speed are determined and compared in the above techniques. Simulation results presented in this paper highlight the improvements produced by the proposed control method based on the extended Kalman filter under various operation conditions.
This document presents a comparative study of five-level and seven-level diode-clamped inverters controlled by space vector pulse width modulation (SVPWM). MATLAB/SIMULINK models of the two inverter topologies were developed. SVPWM control algorithms based on symmetrical sequence were used for each inverter. Both inverters were simulated driving an induction motor. The results showed that the seven-level inverter produced less harmonic distortion and torque fluctuations in the motor, while the five-level inverter had lower commutation losses. The seven-level inverter provided better motor dynamic response.
Sharing of the Output Current of A Voltage Source Inverter between Controlled...IDES Editor
When a two level VSI feeds an induction motor, the
motor current is almost sinusoidal though the voltages at the
terminals have substantial high frequency harmonics. Further
the load current is shared between the controlled switch and
the antiparallel diodes .These essential features of a two level
VSI are studied in this paper using MATLAB simulation.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Improvement the voltage stability margin of Iraqi power system using the opti...IJECEIAES
The detection of potential voltage collapse in power systems is essential to maintain the voltage stability in heavy load demand. This paper proposes a method to detect weak buses in power systems using two stability indices: the voltage stability margin factor (dS/dY) and the voltage collapse prediction index (VCPI). Hence, the paper aims to improve the voltage stability of Iraqi transmission grid by allocating FACTS devices in the optimal locations and optimal sizes. Two types of FACTS are used in this paper which are Thyristor controlled series compensator (TCSC) and static var compensator (SVC). The objective function of the problem is fitted using particle swarm optimization (PSO). The proposed method is verified using simulation test on Diyala-132 kV network which is a part of the Iraqi power system. The results observed that improvement the voltage stability margin, the voltage profile of Diyala-132 kV is increased and the power losses is decreased.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
This document summarizes a research paper that proposes three direct torque control (DTC) strategies for brushless DC motors fed by a four-switch inverter (B4-inverter) to reduce torque ripple. It first reviews the operation of BLDC motors with six-switch (B6-inverter) and B4-inverters, including two-phase and three-phase conduction modes. It then describes three DTC strategies: DTC-1 adapted from B6-inverter control, DTC-2 with a vector selection table to independently control phase torques, and proposed DTC-3 to eliminate torque dips of DTC-2 during sector transitions. Experimental results show DTC-
This document provides instructions for connecting the windings of a three-phase transformer in delta-delta and wye-wye configurations. It describes verifying the phase relationships by measuring voltages before closing the secondary windings. For a delta connection, the voltage within the closed delta must be zero to avoid high currents. The procedure involves connecting the transformer, measuring voltages to check phase relationships, closing the secondary delta if voltages are correct, and measuring secondary line voltages.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
The document provides an overview of the SimPowerSystems library in Simulink, which contains blocks for modeling and simulating electrical power systems. It contains nine sublibraries for modeling various electrical components including sources, elements, transformers, breakers, lines, power electronics, machines, measurements and control blocks. The SimPowerSystems library allows modeling and simulation of electrical circuits, electrical machines, drives, static converters and complete power energy systems. It can be used to model and analyze power systems and their dynamic behavior.
Speed Control System for BLDC Motor by using Direct Back EMF Detection Mathodijtsrd
BLDC motors are used in many industrial and traction applications due to high efficiency, low maintenance and high torque. For good performance of BLDC motors, the accurate knowledge of the rotor position is required. The need for the rotor position information in BLDC motors have been satisfied by use of some form of rotor position sensors. But to reduce cost, complexity and also to improve reliability of the system, sensor less drive system is preferred. In this paper, the development of sensor less control system for BLDC motor using a direct back EMF detection method is presented and simulation for proposed system is done with the help of MATLAB SIMULINK. Soe Sandar Aung | Thet Naing Htun "Speed Control System for BLDC Motor by using Direct Back EMF Detection Mathod" 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/ijtsrd26624.pdfPaper URL: https://www.ijtsrd.com/engineering/electrical-engineering/26624/speed-control-system-for-bldc-motor-by-using-direct-back-emf-detection-mathod/soe-sandar-aung
Power Circuits and Transforers-Unit 8 Labvolt Student Manualphase3-120A
This exercise explores connecting transformers in parallel and measuring their efficiency. Two 100-VA transformers are connected in parallel to supply a 200-VA load. Efficiency is calculated as the ratio of output power to input power. Measurements of input and output power will be taken to determine the overall efficiency and verify that the load is shared between the two transformers. Connecting transformers in parallel allows supplying power greater than the rating of a single transformer.
Application of SVM Technique for Three Phase Three Leg Ac/Ac Converter TopologyIOSR Journals
This paper presents a simulation of a three-phase three-leg AC/AC converter topology using nine IGBTs and space vector pulse width modulation (SVM) technique. The proposed topology reduces the number of switches compared to conventional back-to-back and matrix converters. Simulation results show the converter provides sinusoidal input and output voltages with unity power factor under constant frequency and variable frequency operation. Experimental results from a 5kVA prototype verify the validity of the proposed scheme.
A Study of SVC’s Impact Simulation and Analysis for Distance Protection Relay...IJECEIAES
This paper focuses on analyzing and evaluating impact of a Static Var Compensator (SVC) on the measured impedance at distance protection relay location on power transmission lines. The measured impedance at the relay location when a fault occurs on the line is determined by using voltage and current signals from voltage and current transformers at the relay and the type of fault occurred on the line. The MHO characteristic is applied to analyze impact of SVC on the distance protection relay. Based on the theory, the authors in this paper develop a simulation program on Matlab/Simulink software to analyze impact of SVC on the distance protection relay. In the power system model, it is supposed that the SVC is located at mid-point of the transmission line to study impact of SVC on the distance relay. The simulation results show that SVC will impact on the measured impedance at the relay when the fault occurs after the location of the SVC on the power transmission line.
The document discusses reactive power compensation using a STATCOM. It describes various compensation schemes including shunt capacitors, synchronous condensers, SVCs, and STATCOMs. STATCOMs offer fast response times and can compensate for both lagging and leading reactive power. The document then examines the operating principle, control strategies using variable voltage and phase angle control, simulation circuits, reactive power calculations, voltage and current waveforms, and proposed control strategies for STATCOMs, including decoupling Id and Iq currents to improve system response and stability.
Statcom control scheme for power quality improvement of grid connected wind e...Kinnera Kin
This project aims to improve power quality for a grid-connected wind energy system using a STATCOM. The objectives are to maintain unity power factor at the source, meet reactive power needs of the wind generator and non-linear load, and provide fast response using hysteresis current control for the STATCOM. MATLAB/Simulink software is used to simulate the system both with and without STATCOM. The simulation results show that with STATCOM, harmonic distortion is eliminated in the load current and power quality is maintained at the point of common coupling.
The document summarizes the key points of the Consumer Protection Act of 1986 in India. It outlines who is considered a consumer, what rights consumers have, and protections from unfair trade practices, defects, and more. Standards marks like ISI, hallmark, and AG mark are explained which guarantee quality and purity of goods. Weights and measures are important tools to protect consumers from short weights.
Recent simulation for Reactive power compensation using STATCOM that is Static Syncronous compensator on MATLAB software. It having lots of advantages over other conventional methods.
This document discusses transformer protection philosophy and methods. It describes various types of faults that can occur in transformers like ground faults, phase-to-phase faults, interturn faults, and core faults. It also discusses mechanical protections like Buchholz relay, sudden pressure relay, pressure relief valve, and temperature indicators. Electrical protections discussed include biased differential relay protection and harmonic restraint. The document provides details on how these protections work and their settings.
This document provides an overview of reactive power compensation. It defines reactive power compensation as any device connected in series or parallel with a load to supply the reactive power demanded. There are two main types of compensation: shunt compensation using parallel capacitors to improve power factor and boost voltage, and series compensation using series capacitors to boost receiving end voltage and transmission capacity. Fixed compensation uses breaker controlled capacitors for constant loads, while dynamic compensation uses thyristor controlled capacitors for fluctuating loads. Benefits include better efficiency, improved voltage, reduced losses and higher load capability. Capacitors are used as they generate reactive power to supply loads.
This document summarizes a micro hydro power plant project with unmanned power distribution. The project uses common components like a water tank, flywheel turbine, water level detector, pump, motor and generator to harness energy from flowing water without human operation. It has potential applications for small-scale power generation for homes or industries using water sources like small rivers or canals. The system could help provide electricity in rural areas and reduce reliance on non-renewable energy sources.
This document presents an overview of reactive power compensation. It defines reactive power compensation as managing reactive power to improve AC system performance. There are two main aspects: load compensation to increase power factor and voltage regulation, and voltage support to decrease voltage fluctuations. Several methods of reactive power compensation are discussed, including shunt compensation using capacitors and reactors, series compensation, static VAR compensators (SVCs), static compensators (STATCOMs), and synchronous condensers. SVC and STATCOM technologies are compared, with STATCOMs having advantages of smaller components, better control, and transient response.
Performance Analysis of the Distance Relay Characteristics in a Compensated T...MohammadMomani26
The present work investigates the effect of the FACTS devices on distance relay operation. FACTS devices have different power system performance, stability, and load ability advantages. This paper presents FACTS technologies' effect on the distance protective relay using the measured impedance between the fault location and the relaying point. Different factors and parameters are changed to see their impacts on the studied system. It is shown that the measured impedance is affected by the presence of the FACTS devices depending on their type (series, parallel, and hybrid), fault location, and the operation point of the FACTS device. The analyses present that the shunt FACTS devices' effect may cause overreach problems to the relay; however, series FACTS devices may cause underreach problems in distance characteristics. MATLAB 2019b does the simulation test; the simulation results prove the mathematical analysis. The numerical analysis in this paper may be used for researchers in fault analysis and protection coordinators.
Impact of Thyristor Controlled Series Capacitor Insertion on Short-circuit Ca...IJAPEJOURNAL
This research paper presents a study on phase to earth fault short-circuit calculation with fault resistance on a single transmission line 400 kV in eastern Algerian transmission networks at Algerian Company of Electricity and Gas (Sonelgaz Group) compensated by series Flexible AC Transmission System (FACTS) i.e. Thyristor Controlled Series Capacitor (TCSC) installed in midline. The facts are used for controlling transmission voltage, power flow, reactive power, and damping of power system oscillations at high power transfer levels. The direct impacts of TCSC insertion on the total impedance, active power and reactive power a electrical transmission line and also parameters of short-circuit : symmetrical currents, line currents, symmetrical voltages and line voltages are carried out. More the effects of injected voltage by TCSC for three case studies are presented.
Impact Analysis of Midpoint Connected STATCOM on Distance Relay PerformanceRadita Apriana
This paper presents the impact of the Static Synchronous Compensator (STATCOM) on the
performance of distance protection of EHV transmission lines. A 400kV transmission system having
midpoint connected STATCOM with its control circuit is modeled using MATLAB/SIMULINK software. The
impact of STATCOM on distance relay for different fault conditions and different fault locations is analyzed.
Simulation results indicate that the presence of the STATCOM in the transmission system significantly
changes the line impedance seen by the distance relay to be lower or higher than the actual line
impedance. Due to this the performance of the distance relay changes, either overreaches or under
reaches.
Voltage support to grid under unbalance rodrigujeDeepak Gehlot
This document describes research into using a STATCOM (static synchronous compensator) to regulate voltage at the point of common coupling (PCC) in an unbalanced power system. It proposes a novel PCC voltage controller in synchronous reference frame that independently controls the positive and negative voltage sequences. The controller aims to compensate for an unbalanced PCC voltage and improve system performance. Models of the grid under unbalanced conditions are developed, and the control scheme and design are detailed. Simulation results demonstrate the effectiveness of the novel PCC voltage control approach.
The traction inverter is a crucial power device in the electric vehicle’s powertrain, and its failure is intolerable as it would considerably compromise the system’s safety. For more reliable driving, installing a traction inverter that is sufficiently resistant to electrical failure is inherent. Due to its compact size and the small number of switches incorporated in three-phase four-switch inverter, this modular topology was used to compensate for the open switch’s failure. However, it is known to have manifold weaknesses mainly distinguished in the low-frequency region. This paper introduces a new fault-tolerant indirect control that handles the IGBT’s failure constituting the traction inverter. The fault compensator is designed first based on the Proportional Integral regulator combined with the notch filter to mitigate the current imbalance and restore the DC voltage equilibrium.Furthermore, to conceive a comprehensive fault-tolerant control, there must therefore contain an accurate fault detector. In this regard, an uncomplicated fault diagnosis method based on the current spectral analysis has been performed. The effectiveness of the submitted controller was validated by simulation using Matlab.
IRJET- Design a Fuzzy Distance Relay Including STATCOM EffectsIRJET Journal
This document discusses how the presence of a STATic synchronous COMpensator (STATCOM) can negatively impact the performance of a distance relay used to protect transmission lines. The authors use MATLAB/PSAT to model a sample power system with a transmission line protected by a distance relay. They simulate faults on the line with and without a STATCOM present and observe how the STATCOM causes issues like under-reach and over-reach for the relay. To address this, they propose designing a new fuzzy logic-based distance relay that accounts for the effects of STATCOM compensation to more accurately detect faults.
Modeling of solar array and analyze the current transientEditor Jacotech
Spacecraft bus voltage is regulated by power
conditioning unit using switching shunt voltage regulator having
solar array cells as the primary source of power. This source
switches between the bus loads and the shunt switch for fine
control of spacecraft bus voltage. The effect of solar array cell
capacitance [5][6] along with inductance and resistance of the
interface wires between solar cells and power conditioning
unit[1], generates damped sinusoidal currents superimposed on
the short circuit current of solar cell when shunted through
switch. The peak current stress on the shunt switch is to be
considered in the selection of shunt switch in power conditioning
unit. The analysis of current transients of shunt switch in PCU
considering actual spacecraft interface wire length by
illumination of solar panel (combination of series and parallel
solar cells) is difficult with hardware simulation. Software
simulation by modeling solar cell is carried out for a single string
(one parallel) in Pspice [6]. Since in spacecrafts number of
parallels and interface cable length are variable parameters the
analysis of current transients of shunt switch is carried out by
modeling solar array with the help of solar cell model[6] for the
actual spacecraft condition.
Modeling of solar array and analyze the current transient response of shunt s...Editor Jacotech
Spacecraft bus voltage is regulated by power
conditioning unit using switching shunt voltage regulator having
solar array cells as the primary source of power. This source
switches between the bus loads and the shunt switch for fine
control of spacecraft bus voltage. The effect of solar array cell
capacitance [5][6] along with inductance and resistance of the
interface wires between solar cells and power conditioning
unit[1], generates damped sinusoidal currents superimposed on
the short circuit current of solar cell when shunted through
switch. The peak current stress on the shunt switch is to be
considered in the selection of shunt switch in power conditioning
unit. The analysis of current transients of shunt switch in PCU
considering actual spacecraft interface wire length by
illumination of solar panel (combination of series and parallel
solar cells) is difficult with hardware simulation. Software
simulation by modeling solar cell is carried out for a single string
(one parallel) in Pspice [6]. Since in spacecrafts number of
parallels and interface cable length are variable parameters the
analysis of current transients of shunt switch is carried out by
modeling solar array with the help of solar cell model[6] for the
actual spacecraft condition.
Wavelet based detection and location of faults in 400kv, 50km Underground Po...ijceronline
This document presents a method for detecting and locating faults in underground power cables using wavelet transforms. A 400kV, 50km underground cable system is modeled in MATLAB Simulink. Various single-phase, two-phase, and three-phase faults are simulated at distances of 25km and 50km from the measurement point. Voltage and current signals are analyzed using continuous wavelet transforms to detect and locate faults. Simulation results show the method can accurately estimate fault locations, with errors generally under 7%. The method is capable of determining fault type and location for both transmission and distribution cables.
International Journal of Computational Engineering Research (IJCER) ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Design And Simulation Of Distributed Statcom Controller For Power Factor Impr...IJERA Editor
The STATCOM is a static reactive power compensator. It is connected to the grid through ac side reactors and
has a capacitor on the DC-link side. This DC-link capacitor is maintained at a given voltage under closed-loop
control while a set amount of reactive current is fed according to load requirements. The operating frequency of
the VSC is also controlled in a PLL (phase locked loop) manner. Hence, it is essential to have a closed-loop
feedback control operation of the STATCOM. The state space model of the STATCOM is non-linear. The nonlinear
model of the STATCOM is linearized. A linear model of the STACOM is proposed. In this model, the
grid voltage and the fundamental component of the STATCOM VSC terminal voltage are assumed to be inphase
and the modulation index is kept within unity. PI-controllers for the active and reactive currents as well as
the DC-link voltage of the STATCOM have been designed. The model, with PI controllers has been simulated
in MATLAB/SIMULINK environment with variation of the pre-charge voltage on the DC-link capacitor with
linear loads (inductive). Improvement of the power factor of the grid current is achieved for linear loads.
This document analyzes how various phenomena can affect distance protection settings and measurements. It examines the impact of fault impedance, changes in ground resistivity affecting zero sequence impedance, mutual zero sequence impedance between parallel lines, and infeed effects. The analyses were performed on a real 115kV system using simulation software. Fault impedance can cause apparent impedance measurements to shift into different zones. Changes in ground resistivity can result in underreach if not accounted for. Mutual coupling and infeed effects can also distort impedance measurements if not considered in protection settings.
1. The document analyzes the effect of distributed capacitance on distance relay tripping characteristics for extra high voltage/ultra high voltage transmission lines. It discusses how to properly set distance relays to avoid overreaching or underreaching when considering the effects of distributed capacitance.
2. Equations are presented to calculate the apparent impedance seen by distance relays both with and without considering the effects of transmission line capacitance and fault resistance.
3. Ideal tripping characteristics are defined based on system conditions, and simulations are performed to generate tripping characteristics for a sample 400kV transmission line both with and without considering distributed capacitance. Significant differences are observed.
Reach and Operating Time Correction of Digital Distance Relay Yayah Zakaria
Current and voltage signals recieved from conventional iron core Current Transformer (CT) and Voltage Transformer plays very important role for correct operation of Distance Distance Relay (DDR). Increase in secondary burden connected to CT causes it to saturate at earlier stage. The saturated CT produces distorted secondary current, causing DDR to under reach and to operate by certain time delay. Rogowski Coils (RCs) are attaining increased acceptance and use in electrical power system due to their inherent linearity, greater accuracy and wide operating current range. This paper presents use of RC as an advanced measurement device suitable for DDR. Case study for validation of use of RC is carried out on low voltage system. The simulation results of Distance protection scheme used for protection of part of 220kV AC system shows excellent performance of RC over CT under abnormal conditions.
Reach and Operating Time Correction of Digital Distance Relay IJECEIAES
Current and voltage signals recieved from conventional iron core Current Transformer (CT) and Voltage Transformer plays very important role for correct operation of Distance Distance Relay (DDR). Increase in secondary burden connected to CT causes it to saturate at earlier stage. The saturated CT produces distorted secondary current, causing DDR to under reach and to operate by certain time delay. Rogowski Coils (RCs) are attaining increased acceptance and use in electrical power system due to their inherent linearity, greater accuracy and wide operating current range. This paper presents use of RC as an advanced measurement device suitable for DDR. Case study for validation of use of RC is carried out on low voltage system. The simulation results of Distance protection scheme used for protection of part of 220kV AC system shows excellent performance of RC over CT under abnormal conditions.
Power System’stransmission Line Relaying Improvement Using Discrete Wavelet T...IJERA Editor
Transmission line is a path between the generating station and load(Industries & Domestic). These lines are several kilometres and always attracted towards faults. These Faults are Phase to Ground (P-G), Phase to Phase (P-P), Phase to Phase to Ground (P-P-G) and Symmetrical Fault (P-P-P\P-P-P-G).In order to protect the power system, faults should be cleared within stipulated time. Relay plays a key role in power system protection, before employing them in system, their parameters should be pre-determined.The proposed system uses Discrete Wavelet Transform to determine the fault levels in power system. It is used to extract the hidden factors i.e. Transients, from the faulty current signals by performing decomposition at different levels. Test system is modelled and fault signals are imported to workspace and test the reliability of the algorithm. The proposed system modelled in MATLAB\SIMULINK to detect, classify and locate all the possible faults in the transmission line in the power system which are nothing but parameters of relays.
Direct Torque Control of A 5-Phase Induction Motorijsrd.com
In this paper an effective direct torque control (DTC) for a 5-phase induction motor with sinusoidal distributed windings is developed. First by coordinate transformation, the converter/motor models are represented by two independent equivalent d-q circuit models; and the 5- phase VSI input are decoupled into the torque producing and non-torque producing harmonics sets. Then with the torque production component of the induction motor model, the space vector modulation (SVM) can be applied to the fivephase induction motor DTC control, resulting in considerable torque ripple reduction over the lookup table method. Based on the decoupled system model, the current distortion issue due to lack of back EMF for certain harmonics is analysed. Two equally effective SVM schemes with the harmonic cancellation effect are introduced to solve this problem. To analyse the DTC control torque ripple, an insightful perspective (also applicable to 3-phase analysis) is introduced to predict the torque ripple pattern evolution with changing motor speed and stator flux angular position. Therefore the switching sequence for lowest torque ripple can be determined and rearranged online.
1) The document describes the simulation of a differential relay for transformer protection using MATLAB/Simulink. A differential relay operates by comparing the current flowing into and out of a transformer and tripping the circuit breaker if there is a difference, indicating an internal fault.
2) The simulation models a power system including a transformer protected by a differential relay. Current transformers measure the primary and secondary currents which are compared in the relay.
3) Under normal operation the currents match and the relay does not trip, but internal faults create a difference that causes the relay to send a trip signal to the circuit breakers to isolate the fault. The simulation tests the relay under different fault conditions.
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Errors analysis in distance relay readings with presence of facts devices
1. Innovative Systems Design and Engineering
ISSN 2222-1727 (Paper) ISSN 2222-2871 (Online)
Vol.4, No.14, 2013
www.iiste.org
Errors Analysis in Distance Relay Readings with Presence of
FACTS Devices
Gaber El-Saady1*Rashad M.Kamel2 Essam M.Ali3
Electrical Engineering Department, Assiut University, Assiut, Egypt, gaber1@yahoo.com
Abstract
This paper presents studying the performance of distance impedance relay with the presence of FACTS
devices .Also the measured impedance at the relaying point in the presence of series FACTS device SSSC ,
and shunt FACTS device called STATCOM are obtained. A detailed model of both SSSC and STATCOM is
introduced and then the faulty system is studied analytically , where the errors in the measured impedance of
distance impedance relay are introduced as a result of the presence of series and shunt FACTS devices. The
analysis results show the effect of impacting the FACTS devices location, the values of inserted SSSC and
STATCOM voltages (operational conditions) and also the fault resistance values.
Keywords: Distance Relay, FACTS, STATCOM, SSSC.
1. Introduction
The measured impedance at the relaying point is the basis of distance protection operation. In addition to the power
system parameters, the fault resistance could greatly influence the measured impedance in the case of single phase to
ground, double phase to ground and three phase to ground faults, in such a way that for zero fault resistance the
power system parameters do not affect the measured impedance (Kazemi & Jamali 2009). FACTS devices can
be broadly classified into three types, (a) Shunt (b) Series and (c) composite series and shunt (Tarlochan et al. 2005).
The use of power electronics devices to improve power transfer capability of long transmission lines forms
the basis of the concept of FACTS. The Static Synchronous Series compensator (SSSC) is a series device of the
FACTS family using power electronics to control power flow and improve power oscillation damping on power
grids (Khederzadeh 2009).
More than 70% of transmission line faults are single phase to earth faults, and phase to phase faults are the next
common fault type . Double phase to earth and three phase faults are less common in power transmission
systems (Jamali & Shateri,2011). The operating principle of distance protection is based on the fact that , from
any measuring point in power system the line impedance to a fault in that system can be determined by measuring
the voltage and current at the measuring point (Khederzadeh 2009).
Some researchers have been done to evaluate the performance of a distance relay for transmission line in the
presence of FACTS controllers. The work in (Kazemi & Jamali 2009) presented a steady state analysis on
impacting STATCOM and SSSC and compared between SSSC and STATCOM impacting effects on the measured
impedance by distance relay. The work in (Khederzadeh 2009) presented analytical and simulation results of the
application of distance relays for the protection of transmission employing Static Synchronous Series Compensator
(SSSC).
This paper studied the effects of the installation of SSSC and STATCOM on a doubly fed circuit transmission line
in the case of single line to ground fault by means of presenting the errors in measured impedance at the relaying
point and the distance relay ideal tripping impedance values. The measured impedance is presented for two cases of
SSSC and STATCOM exclusion and inclusion in the fault loop. For three installation points of SSSC, i.e. at near
end, mid-point, and far end, the ideal tripping characteristic is investigated. Also the operational conditions of
FACTS that may be affected by loading condition are considered in this work.
2-FACTS devices models
The Facts devices under study have different types; the model of each type is described in the following sections.
2.1. SSSC model
The SSSC is placed in a group of series connected FACTS devices. As shown in figure (1) SSSC consists of a
voltage source connected in series with the transmission line through voltage source inverter (VSI) and coupling
transformer.
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Vol.4, No.14, 2013
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Figure (1) (a) Basic construction
(b): an equivalent circuit of SSSC
2.2. STATCOM model
A STATCOM is a controlled reactive power source and provides voltage support, which is its primary duty, by
generating or absorbing reactive power at the point of common coupling without the need of large external
reactors or capacitor banks (Prof. Detlef 2007).
The STATCOM basically consists of a step down transformer Tr, reactance LF, a three phase GTO or IGBT based
multi- pulse VSC and a DC capacitor as shown in figure (2a). STATCOM can be modelled as a shunt branch
consisting of an impedance Zsh due to the coupling transformer, and a voltage source Esh which is in phase with the
voltage of its connection point (Kazemi & Jamali 2009).
Figure (2) (a) STATCOM model construction
(b) STATCOM representation
2.3. The system model
The system model under studying here is a single circuit transmission line fed doubly from two generators EA and
EB where EB=EAhe-jδ. Our FACTS devices are inserted between bus A and bus B to control the transferred power,
voltage and current of line, etc. The distance relay is placed at bus A, so its function is protecting the transmission
line till point B see figure (3).
Figure (3): the model of the system consists of doubly fed transmission line
3. Fault analysis
Operating times of protective relays are typically 1.0–3 cycles and the tripping times of breakers are 1.5 – 3
cycles, giving a total fault tripping time of 2.5– 6 cycles (50 –120 ms at 50 Hz, 42–100 ms at 60 Hz) . The relays
are installed on each feeder at a substation, to which the secondary voltages and currents of the VT (voltage
transformers) and CT (current transformers) of the associated feeder line are applied as shown in Fig4. The signal
voltage V (t) and current I (t) from the secondary terminals of the associated PT and CT are applied to the relay, and
the new quantities u (t), ν’ (t) compose the detected part of the relay circuit as shown in the figure (4b). Then the
phase angular difference between u (t) and ν’ (t) is continuously compared in the phase comparator part of the relay
circuit (Xia et al.1994) and (Yi Hu et al. 2002).
In the absence of FACTS devices with zero fault resistance, the measured impedance by a distance relay only
depends on the length of the line section between the fault location and the relaying points. In Figure (3) this
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www.iiste.org
impedance is equal to pZL1, where p is per unit length of the line section between the fault and the relaying points,
and ZL1 is the line positive sequence impedance in ohms. In the case of a non-zero fault resistance, The measured
impedance is not equal to the impedance of the line section between the relaying and the fault points. In this
case, the structural and operational conditions of the power system affect the measured impedance (Kazemi &
Jamali 2009).
The operational conditions prior to the fault instance can be represented by the load angle of the line δ and the ratio
of the voltage magnitude at the line ends h or EB / EA = h e-jδ. The power system before the fault at point F can be
drawn as a symmetrical circuit in the 1–2–0 domain as shown in figure (5). The fault calculations for impedance
readings will derive now from the first principles case of SLG fault and it is given in appendix A .
Figure (4): (a) principle of fault detection
(b) MHO relay characteristics
Figure (5): the 1-2-0 domain of the model case of fault with no FACTS connection.
3.1. Fault impedance calculation case of no FACTS
See appendix A for more details.
From the equations given in the appendix A the predicted measured impedances with changing fault location can be
given by the following equations:
ZA1 = ZSA1 + p ZL1
(1)
ZB1 = ZSB1 + (1− p) ZL1
(2)
ZA0 = ZSA0 + p ZL0
(3)
ZB0 = ZSB0 + (1-p) ZL0
(4)
Z1=Z2
each positive sequence impedance equal negative sequence one. Where ZA1, ZA2, ZA0 are positive, negative
and zero sequence impedances looking into the left-hand side at point F.
ZB1, ZB2, ZB0 are positive, negative and zero sequence impedances looking into the right-hand side at point F.
Now the two measured quantity Vrelay and Irelay at point A
The relaying current is as follows:
I relay = IA + KOL IA0 = (Cd +2 C1+C0 (1 + 3K0L)) If (1)
The relaying voltage
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(5)
4. Innovative Systems Design and Engineering
ISSN 2222-1727 (Paper) ISSN 2222-2871 (Online)
Vol.4, No.14, 2013
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Vrelay = VA = VF + IAf (p ZL1) = 3 If (1) RF + Irelay (p ZL1)
(6)
From equations (5) and (6) Where Zrelay = Vrelay / Irelay, we found that:
Zrelay = pZL1 +
(7)
C1 = ZB1 / (ZA1 + ZB1)
(8)
C0 = ZB0 / (ZA0 + ZB0)
(9)
Where
C1=C2
because
Z1=Z2
Ze = ZA1+ZB1
(10)
K0L = (ZL0-ZL1) / (3ZL1)
(11)
Kd =1- h e-jᵟ
(12)
-j
D = ZB1+ZA1h e ᵟ
(13)
Cd = (Ze +3 RF) Kd / D
(14)
It can be seen when the fault resistance is equal to zero, the measured impedance at the relaying point is equal to
the impedance of the line section between the relaying and the fault points, and otherwise the measured
impedance deviates from its actual value depending on the power system conditions. Note K0L is Zero sequence
compensated factor.
3.2. Relay impedance with presence of SSSC
Once a FACTS devise is installed on the transmission line, the measured impedance at the relaying point is affected.
The device is installed at the length of m per unit from the relaying point. In the following, the measured impedance
in the presence of SSSC and STATCOM is presented. Inserting SSSC depending on its exclusion or inclusion in the
fault loop, the measured impedance would change. And the following equations are derived with the same previous
sequence. Firstly, some factors are defined:
CSC1 = Zse / ZL1
(15)
CSC0 = Zse / ZL0
(16)
ZAm1 = ZSA1 + mZL1
(17)
ZAm0 = ZSA0 + mZL0
(18)
Inserting SSSC may be at any point on the line and also the fault, so the measured impedance will be affected by
both the FACTS and fault location. Let us check impedance calculations at two locations (1) nearer to far end
than fault point (i.e. SSSC out of fault loop) (2) nearer to near end than fault point (i.e. SSSC inside the fault loop).
3.2.1. SSSC nearer to far end (out of fault loop)
Some equations are modified according to variation of VSSSC and Zse. Fault distance p is smaller than inserting
location m (m > p).
ZBm1 = ZSB1 + (1 – m + CSC1) ZL1
(19)
ZBm0 = ZSB0 + (1 - m + CSC0) ZL0
(20)
ZAf1 = ZSA1 + pZL1
(21)
ZmF1 = |m – p| ZL1
(22)
ZmF0 = |m – p| ZL0
(23)
ZA1 = ZAf1
(24)
ZB1 = Zmf1 + ZBm1
(25)
ZAf0 = ZSA0 + pZL0
(26)
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ZAm0 = (m - p) ZL0
(27)
ZA0 = ZAf0
(28)
ZB0 = Zmf0 + ZBm0
(29)
Dn = ZBn1+ZA1 [h e-jᵟ - re jϒ]
(30)
jᵧ
Kdn = 1+ r e - h e-jδ
(31)
Using the same equation (10) of measured impedance here, the measured impedance in the case of zero fault
resistance is equal to the impedance of the line section between the relaying and the fault points as will be shown
later.
3.2.2. SSSC at near end (inside of fault loop)
In this case the fault location p is larger than FACTS inserting point m (m < p). The equations in previous case will
be modified as follow:
Zmf1 = (p – m + CSC1) ZL1
(32)
ZA1 = ZAm1+ Zmf1
(33)
ZB1 = ZBf1
(34)
Zmf0 = (p – m + CSC0) ZL0
(35)
ZA0 = ZAm0 + Zmf0
(36)
ZB0 = ZBf0
(37)
jᵧ
jᵧ
Dn = [ZAm1 (1 + re ) + Zmf1] h e-jδ + ZBf1 (1 + re )
(38)
CZ = (CSC0 - CSC1) C0 (1 + 3KL0) ZL1
(39)
jᵧ
Cv = - (Ze + 3RF) (ZAn1+ZB1) re / Dn
(40)
Zrelay = (p + CSC1) ZL1 +
(41)
It can be seen obviously that when (RF = 0) no fault resistance , the measured impedance will not be the same
as pZL1 because of the effect FACTS presence.
3.3. Relay impedance with presence of STATCOM
Inserting STATCOM in the line depending on its position with respect to fault location (inside or outside fault
location) affect the measured impedance, so some equations are modified with STATCOM with STASTCOM
voltage = Esh and an impedance ZSh as follows :
ZAm1 = ZSA1 + mZL1
(42)
ZBm1 = ZSB1 + (1 - p) ZL1
(43)
ZAm0 = ZSA0 + m ZL0
(44)
ZBm0 = ZSB0 + (1 - p) ZL0
(45)
Zmf1 = |m - p| ZL1
(46)
Zmf0 = |m - p| ZL0
(47)
These equations specify the behaviour of no fault impedances independently of inserting FACTS inside or outside
fault loop.
3.3.1. STATCOM nearer to far end (out of fault loop)
The following equations are modified also according to insertion point location.
ZA1 = ZAf1
(48)
ZB1 = Zmf1 +
(49)
ZA0 = ZAf0
(50)
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ZB0 = Zmf0 +
(51)
Dn =
(52)
Kdn = 1- esh (1 – CB1) – CB1 h e
-jδ
(53)
And using equation (10) it can be observed that in case of zero fault resistance, the relay measured impedance
is equal to pZL1. Otherwise the relay impedance will have impedance different from pZL1.
3.3.2. STATCOM nearer to near end (inside fault loop)
Some modifications are performed according to point m and p locations with respect to each other.
Dn =ZAn1 + ZB1 – (CA1 + eSh (1 – CA1) – h e -jδ) (Cm ZAm1 + ZAn1)
Kdn= 1 – hn e
(54)
-jδ
(55)
Cdn = (Ze + 3 RF) Kdn / Dn
(56)
Csh = Zmf1 (- CV + (1-CA1) (Cdn + 2C1) + C0 (1- CA0) (1 + 3K0L))
(57)
Zrelay = pZL1 +
(58)
It is obvious also that when RF = 0, the relay impedance is not equal to pZL1 as will be discussed later.
4. Case Study and Results
We choose in our study three important points of impacting of FACTS through transmission lines (1) at near end (2)
at far end (3) at midpoint impacting. Power system calculations gave these impedance values of the system shown in
fig .3.
ZL1 = 0.01133 + j 0.3037
Ώ/KM
ZL0 = 0.1535 + j 1.1478
Ώ/KM
ZSA1 = 1.3945 + j 15.9391
Ώ
ZSA0 = 7.454 + j 27.8187
Ώ
ZSB1 = 0.6972 + 7.9696
Ώ
ZSB0 = 3.7270 + j 13.9093
Ώ
h= 0.96
δ=16˚
The ideal tripping impedance readings without FACTS are shown in figure (6a) and the errors in readings due to
presence of fault resistance as in figure (6b).
tripping characteristics
the reading errors in resistance
100
350
Rf = 0
Rf = 100
Rf= 200
300
R errors in ohm
90
80
70
250
200
150
100
50
60
0
0.1
0.2
0.3
0.4
0.5
percentage distance
0.6
0.7
0.8
0.9
1
0.6
0.7
0.8
0.9
1
the reading errors in reactance
10
40
5
30
X errors in ohm
X relay
0
50
20
10
0
-5
-10
-15
0
0
50
100
150
200
R relay
250
300
350
-20
0
0.1
0.2
Figure (6) (a) tripping characteristics
0.3
0.4
0.5
percentage distance
(b) errors due to RF presence
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From the above figure it is observed that when a bolt fault occurred, the angle of measured impedances were
constant and the magnitudes only changed or say that both the measured resistance and reactance values
changed with the same percentage with changing the fault location. Unlike the previous case, case of fault
occurrence through resistance Rf≠0 both the angles and magnitudes changed. As shown in figure 6 the resistance
increased but the reactance decreases compared with case of bolt fault.
4.1. FACTS at far end (outside fault loop)
4.1.1. SSSC impacting
From equation (10) , there is no error at any value of VSSSC when a bolt fault occurred at any value of SSSC
injected voltage. The results in fig.7 shows the errors occurred in impedance (resistance and reactance)
readings case of fault occurrence through resistance Rf = 50 ohm . With changing the fault location, the
errors in resistance were negative what means that resistance decreased compared with original case in fig6,
also the reactance decreased with small changes, but at the end of the line fault occurrence the error was larger.
With increasing the values of injected voltage we observe that readings error increased negatively in both resistance
and reactance.
errors in Rrelay with Rf = 50.0 ohm
20
R errors in ohm
0
-20
r=0.0
r= 0.1
r = 0.2
-40
-60
-80
0
10
20
30
40
50
percentage distance p
60
70
80
90
100
60
70
80
90
100
errors in Xrelay with Rf = 50.0 ohm
5
X errors in ohm
0
-5
-10
-15
-20
-25
-30
0
10
20
30
40
50
percentage distance p
Figure (7) errors in readings with SSSC insertion out of loop with RF =50 Ώ
With increasing the fault resistance Rf, Comparing fig8 with fig.7 we can note that readings error increased
comparing leading SSSC with inactive one . In some details, the errors in resistances increased unlike reactance
errors. Resistances are lower values compared with original case.
errors in Rrelay with Rf = 200.0 ohm
50
R errors in ohm
0
-50
r=0.0
r= 0.1
r = 0.2
-100
-150
0
10
20
30
40
50
percentage distance p
60
70
80
90
100
70
80
90
100
errors in Xrelay with Rf = 200.0 ohm
10
X errors in ohm
0
-10
-20
-30
-40
0
10
20
30
40
50
percentage distance p
60
Figure (8) errors in readings with SSSC insertion out of loop with R F =200 Ώ
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4.1.2 STATCOM impacting
From equation (10), it is obvious that case of a bolt fault the errors in readings disappeared at any value of
STATCOM injected current (or voltage). The results in figure (9) shows the errors in impedance relay readings
case of fault occurrence through resistance Rf = 50 Ώ. The errors in resistances are positive what shows that the
resistance readings are higher than original case. but the reactance errors are negative values although the
errors are smaller compared with SSSC impacting .
errors in Rrelay with Rf = 50.0
6
Ef=1.0
Ef=1.1
Ef=0.9
R errors in ohm
5
4
3
2
1
0
0
0.1
0.2
0.3
0.4
0.5
percentage distance p
0.6
0.7
0.8
0.9
1
0.6
0.7
0.8
0.9
1
errors in Xrelay with Rf = 50.0
1
X errors in ohm
0
-1
-2
-3
0
0.1
0.2
0.3
0.4
0.5
percentage distance p
Figure (9) errors in readings with STATCOM insertion out of loop with R F =50 Ώ
Giving a careful consideration to figure 10 that shows the errors with changing fault location and
STATCOM voltage (Esh) but at higher fault resistance (Rf = 200 Ώ). We can observe that impedance
readings diverge slowly from the original case at inactive STATCOM. Comparing leading STATCOM
with inactive one we can say that the errors are within a convergent values but errors in reactance are
higher than resistance one.
errors in Rrelay with Rf = 200.0
5
Ef=1.0
Ef=1.1
Ef=0.9
R errors in ohm
4
3
2
1
0
0
0.1
0.2
0.3
0.4
0.5
percentage distance p
0.6
0.7
0.8
0.9
1
0.6
0.7
0.8
0.9
1
errors in Xrelay with Rf = 200.0
4
X errors in ohm
2
0
-2
-4
-6
0
0.1
0.2
0.3
0.4
0.5
percentage distance p
Figure (10) errors in readings with STATCOM insertion out of loop with R F =200 Ώ
4.2. FACTS at near end
4.2.1. SSSC impacting
Back to equation (43) when a belt fault occurred, there are errors due to the presence of SSSC inside fault
loop. By scrutiny in figure (11) the errors case of an inactive SSSC are very small in both resistance and reactance
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readings but these values differed obviously in leading SSSC devices by increasing the injected voltage as
shown.
Increasing the injected voltage of SSSC resulted in observable values in impedance readings errors as seen in
figure (11).
errors in Rrelay with Rf = 0.0 ohm
20
r=0.0
r= 0.1
r = 0.2
R errors in ohm
15
10
5
0
-5
0
10
20
30
40
50
percentage distance p
60
70
80
90
100
60
70
80
90
100
errors in Xrelay with Rf = 0.0 ohm
4
X errors in ohm
2
0
-2
-4
-6
0
10
20
30
40
50
percentage distance p
Figure (11) errors in readings with SSSC insertion in loop with R F =0.0 Ώ
By increasing the fault resistance the situation has became worst and the errors had larger values as obvious by
comparing the results in figs 11 and 12. The errors commensurate with voltage injection were in a negative manner.
The errors in impedance readings are at unacceptable levels in reactance and resistance especially where a fault
occurs at far end side.
errors in Rrelay with Rf = 200.0 ohm
20
R errors in ohm
0
-20
-40
r=0.0
r= 0.1
r = 0.2
-60
-80
-100
-120
0
10
20
30
40
50
percentage distance p
60
70
80
90
100
70
80
90
100
errors in Xrelay with Rf = 200.0 ohm
10
X errors in ohm
0
-10
-20
-30
-40
0
10
20
30
40
50
percentage distance p
60
Figure (12) errors in readings with SSSC insertion in loop with R F =200.0 Ώ
4.2.2. STATCOM impacting
During a bolt fault in the presemce of STATCOM the errors in resistance can be neglected but in reactance; errors
are considered as shown in fig13.
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errors in Rrelay with Rf = 00.0
6
Ef=1.0
Ef=1.1
Ef=0.9
R errors in ohm
5
4
3
2
1
0
0
0.1
0.2
0.3
0.4
0.5
percentage distance p
0.6
0.7
0.8
0.9
1
0.6
0.7
0.8
0.9
1
errors in X
relay with Rf = 00.0
14
X errors in ohm
12
10
8
6
4
2
0
0
0.1
0.2
0.3
0.4
0.5
percentage distance p
Figure (13) errors in readings with STATCOM insertion in loop with RF =0.0 Ώ
By increasing the fault resistance the resistance readings decreased but reactance readings increased slowly see
figure 14.
errors in Rrelay with Rf = 200.0
30
R errors in ohm
20
10
0
Ef=1.0
Ef=1.1
Ef=0.9
-10
-20
-30
0
0.1
0.2
0.3
0.4
0.5
percentage distance p
0.6
0.7
0.8
0.9
1
0.6
0.7
0.8
0.9
1
errors in Xrelay with Rf = 200.0
40
X errors in ohm
20
0
-20
-40
-60
0
0.1
0.2
0.3
0.4
0.5
percentage distance p
Figure (14) errors in readings with STATCOM insertion in loop with R F =200.0 Ώ
4.3. FACTS at midpoint
In this case, both SSSC and STATCOM are out of the fault loop for faults on the near half of the line, while
they are introduced in the fault loop for faults on the far half one.
4.3.1. SSSC impacting
In the presence of SSSC at the midpoint the impedance errors are split into two parts. The right part (from p = 0.5
1 ) is for the faults on the near half of the line, while the left part (p=0 0.5 ) is corresponding to the faults
on the far half.
Figure (15) shows that at a bolt fault in the right part; increasing the injected voltage has no effect on impedance
relay readings. On the other hand in the right side the injected voltage magnitude resulted in decreasing the
measured reactance and increasing the measured resistance.
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errors in Rrelay with Rf = 0.0
20
R errors in ohm
15
r=0.0
r= 0.1
r = 0.2
10
5
0
-5
0
20
40
60
80
100
percentage distance p
120
140
160
180
200
120
140
160
180
200
errors in Xrelay with Rf = 0.0
10
X errors in ohm
0
-10
-20
-30
-40
-50
0
20
40
60
80
100
percentage distance p
Figure (15) errors in readings with SSSC insertion at midpoint with R F =0.0 Ώ
Comparing fig 15 and 16, We can note that case of inactive SSSC the reactance and resistance readings in the left
part are unnoticeable unlike in the right side where errors are more obvious . With increasing the injected
voltage the errors are in negative values in both resistance and reactance readings change obviously.
errors in Rrelay with Rf = 200.0
100
r=0.0
r= 0.1
r = 0.2
R errors in ohm
50
0
-50
-100
-150
0
20
40
60
80
100
percentage distance p
120
140
160
180
200
120
140
160
180
200
errors in Xrelay with Rf =200.0
10
X errors in ohm
0
-10
-20
-30
-40
-50
0
20
40
60
80
100
percentage distance p
Figure (16) errors in readings with SSSC insertion at midpoint with R F = 200.0 Ώ
4.3.2. STATCOM Impacting
Figure (17) shows case of a bolt fault occurrence during impacting STATCOM at midpoint; in the left part
increasing the injected voltage has no effect on impedance relay readings. On the other hand in the right part the
injected voltage magnitude nearly has no effect on the errors in measured reactance and very small effect on the
measured resistance.
errors in Rrelay with Rf = 0.0
R errors in ohm
15
10
Ef=1.0
Ef=1.1
Ef=0.9
5
0
0
0.1
0.2
0.3
0.4
0.5
percentage distance p
0.6
0.7
0.8
0.9
1
0.6
0.7
0.8
0.9
1
errors in Xrelay with Rf = 0.0
35
X errors in ohm
30
25
20
15
10
5
0
0
0.1
0.2
0.3
0.4
0.5
percentage distance p
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Figure (17) errors in readings with STATCOM insertion at midpoint with RF = 0.0 Ώ
By increasing the fault resistance; in the left part of fig18 the measured resistance errors increased slightly with
increasing the injected voltage unlike reactance readings that decreased slightly. On the other hand at the
right part with increasing the injected voltage (Esh), very small effects appeared on resistance also on
reactance but with higher manner than resistances. Fortunately the errors in STATCOM are lower than that of
SSSC.
errors in Rrelay with Rf = 200.0
50
Ef=1.0
Ef=1.1
Ef=0.9
R errors in ohm
0
-50
-100
-150
0
0.1
0.2
0.3
0.4
0.5
percentage distance p
0.6
0.7
0.8
0.9
1
0.6
0.7
0.8
0.9
1
errors in X
relay with Rf = 200.0
20
X errors in ohm
15
10
5
0
-5
-10
-15
0
0.1
0.2
0.3
0.4
0.5
percentage distance p
Figure (18) errors in readings with STATCOM insertion at midpoint with RF = 200.0 Ώ
5. Conclusion
The measured impedance has been studied for two cases of FACTS in and out of the fault loop for the installation
points at near end , mid-point , and far end of a transmission line.
Comparing the errors in the measured impedance from its original value, the impedance of the line section
between the relaying and the fault points in the presence of SSSC and STATCOM at the line ends, It can be
concluded as follows :
1- In case of FACTS installed at the far end of the line
a- The measured impedance at absence of fault resistance is the original value. When there was a fault resistance
some errors appeared that could be neglected for STATCOM but can’t for SSSC.
b- When a fault occurred through a resistance RF; increasing the injected voltage of SSSC affected negatively
errors more than increasing STATCOM voltage with the same injected reactive power.
2- In case of FACTS devices at near end of the line
a- There were some errors in impedance readings in SSSC that disappeared with STATCOM case of a bolt fault
occurrence.
b- By increasing the fault resistance the effects of FACTS are more obvious but SSSC effect was higher.
From the above two notes it can be said that the location of impacting FACTS devices from being inside or
outside fault loop is an important uncontrollable factor that affect impedance readings. The operational conditions
(changing Esh and VSSSC) of FACTS also play an effective role in appearance of impedance readings error.
3- In case of FACTS devices at midpoint of the line
When FACTS devices were inserted at midpoint the impedance readings changed obviously between two nearby
points because one of them located inside fault loop and the other one was outside. This study may be considered a
contribution to the protection engineering to easy modify the relay setting according to FACTS impacting
locations and operational condition and that will be our future work (Automatic modification of Distance Relay
Setting Avoiding the Effects of FACTS Devices Impacting).
Appendix (A)
Derivations of relay impedance ZA formulas
1. without facts
Fault current can be calculated as follows:
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Ifa (1) = Ifa (2) =Ifa (2)
(A1)
Where Vf0: pre-fault voltage
Z1, Z2, and Z0: are positive, negative and zero sequence
Where RF: fault impedance
ZA1, 2 = ZSA1 + p ZL1, 2
(A2)
ZA0 = ZSA0 + p ZL0
(A3)
ZB1, 2 = ZSB1 + (1- p) ZL1
(A4)
ZB0 = ZSB0 + (1 – p) ZL0
(A5)
Z1, 2 =
(A6)
Z0 =
(A7)
Ze = Z1 + Z2 + Z0 = 2
+
(A8)
To complete the fault current equation, we need now to calculate the pre-fault voltage Vfo at point f. from kirchauf’s
voltage law (KVL) in figure (2), we can deduce these equations.
Vfo = EA – IApf ZA1
(A9)
IApf =
=
Kd = 1 – h e
=
-jδ
(A10)
(A11)
Using Equation (A11) in Equation (A9), Vfo is derived as follows:
Vf0 = EA -
ZA1 =
=
=
Vf0 =
(A12)
(A13)
D = ZB1 + ZA1 h e-jδ
(A14)
Ifa (1) =
(A15)
(1)
Standing on previous equations; we got Ifa .
As been discussed previously, the work of distance relays depends on two measured quantities; current and voltage
measurable values. We now will deduce these two equations of relay voltage and current at bus A. Using
Kirchhoff’s current law (KCL) in figure (5), we can directly get both negative and zero sequence current values as
follows.
IAf (2) =
Ifa (1) = C1 Ifa (1)
(A16)
IAf (0) =
Ifa (1) = C0 Ifa (1)
(A17)
C1, 0 =
(A18)
KCL is applied only on zero and negative sequence currents only, but positive one has voltage sources. So KVL is
used to get Ifa (1) as shown in figure (A3).
EA – EB = IAf (1) ZA1 - IAf (1) ZB1 = IAf (1) ZA1 - (Ifa (1) - IAf (1)) ZB1
= IAf (1) [ZA1 + ZB1] - Ifa (1) ZB1
124
(A19)
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IAf (1) = C1 Ifa (1) +
(A20)
FigureA3. Positive sequence circuit
=
=
x
= Cd Ifa (1)
(A21)
IAf (1) = (C1 + Cd) Ifa (1)
(A22)
Cd =
(A23)
The relay current is:
IAf = IAf (1) + IAf (2) + IAf (0)
(A24)
For single line to ground fault, the measured voltage will be as follows.
VA= IAf (1) Z1+ IAf (2) Z2+ IAf (0) Z0 =Z1 (IAf (1) + IAf (2)) + Z0 (IAf (0))
Z0 IAf
(0)
= Z1 IAf
(0)
- Z1 IAf
= Z1 IAf
(0)
(0)
+ Z0 IAf
(A25)
(0)
+ [Z1 – Z0] IAf (0)
(A26)
Back to Equation (A25), we can get.
V = Z1 (IAf (1) + IAf (2) + IAf (0)) + [Z1 – Z0] IAf (0)
= Z1 (IAf (1) + IAf (2) + IAf (0) (1+3K0L))
(A27)
Where K0L is called zero sequence compensated factor. And it is used to modify zero sequence impedance to be
positive sequence to treat with relay impedance as positive sequence Z1 only.
K0L = 3
(A28)
IAf = (Cd+2C1+ C0 (1 + 3 K0L)) Ifa (1)
(A29)
After finishing deducing the first quantity (current one) formula, we now want to complete the relay measurable
feedings.
From KVL in figure (2) the relay voltage can be calculated as follows.
VA = VF + IAf p ZL1 =3 Ifa (1) RF + (Cd+2C1+ C0 (1 + 3 K0L)) Ifa (1)
(A30)
So after deducting the two quantity formulas, we can get predictable relay impedance at bus A.
Zrelay =
=
(
)
(
)
Zrelay = PZL1 +
(A31)
A.2. with the presence of SSSC
Regardless the location of SSSC the following equations are valid
CSC1, 0 = ZSC / ZL1, 0
(A32)
ZAf1, 0 = ZSA1, 0 + p ZL1, 0
(A33)
ZBf1, 0 = ZSB1, 0 + (1 - p) ZL1, 0
(A34)
A.2.1. Outside fault loop
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According to figA:
Zmf 1, 0= (m - p) ZL1, 0
(A35)
ZAm1, 0 = ZSA1 + m ZL1
(A36)
ZAm1, 0 = ZSA1, 0 + m ZL1, 0
(A37)
ZA1 = ZAf1
(A38)
ZA0 = ZAf0
(A39)
Calculating the pre-fault current
IApf =
=
(A40)
Pre-fault voltage
Vf0 = EA – IApf ZA1 = EA - ZA1 x
[
=
]
=
(A41)
And with the same previous algorithm in (1), we found that
Dn = ZBn1+ZA1 [h e-jᵟ - re jϒ]
-jϒ
(A42)
-j
Kdn = 1+ re - h e ᵟ
(A43)
A.2.2. Inside fault loop
Zmf1, 0 = (p – m + CSC1, 0) ZL1, 0
(A44)
Zmf1, 0 = (p - m) ZL1, 0
(A45)
ZA1, 0=ZAm1, 0+Zmf1, 0
(A46)
ZB1, 0 = ZBf1, 0
(A47)
Now calculating the pre-fault voltage but noting that the pre-fault current didn’t change because the series voltage
location doesn’t affect the line current.
Vf0 = EA + VSSSC – IApf ZAn1
(A48)
Vf0 = EA + VSSSC [
Vf0 =
ZAn1
(A49)
]
(A50)
Dn = ZB1 (1 + r e jγ) + ZAn1 he-jδ
(A51)
Ifa (1) =
(A52)
Calculating fault current
Calculating the fault relay current. Firstly; using KVL in positive sequence circuit, the positive sequence is derived
as follows:
EA + VSSSC – IAf (1) ZAn1 = EB – IBf (1) ZB1
But IBf
(1)
=Ifa
(1)
– IAf
(A53)
(1)
IAf (1) =
+ C1 Ifa (1) =
=
=
+ C1 Ifa (1)
x
Ending to eq (A14); the relay fault voltage can be calculated as follows:
126
= Cd Ifa (1)
(A54)
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VA = VF – VSSSC + IAfC (p + CSC1) ZL1
(A55)
IAfC: is the compensated relay current due to using ZL1.
VA = 3RF Ifa (1) - VSSSC + (Cd + 2C1 + C0 (1 + 3K0L)) Ifa (1) (p + CSC1) ZL1
- (CSC1 - CSC0) C0 (1 + 3K0L) Ifa (1)
Zrelay = (p + CSC1) ZL1 +
(A56)
(A57)
VSSSC / Ifa (1) =
= (Ze + 3 RF) (ZAn1 + ZB1) re jϒ / Dn
Zrelay = (p + CSC1) ZL1 +
(A59)
CZ = - (CSC1 - CSC0) C0 (1 + 3K0L) ZL1
CV = - (Ze + 3 RF) (ZAn1 + ZB1) re
(A58)
jϒ
/ Dn
(A60)
(A61)
A.3. with the presence of STATCOM
CSh1, 0 = ZSC / ZL1, 0
(A61)
Zmf1, 0 = |p – m| ZL1, 0
(A62)
ZAm1, 0= ZSA1, 0 + m ZL1, 0
(A63)
ZBm1, 0 = ZSB1, 0 + (1- m) ZL1, 0
(A64)
A.3.1. STATCOM Outside fault loop
From figure (A2a), we derived the fault current
calculations are as follows:
using curtailment the Esh and EB sources to one source eq, the fault
CB1, 0 = ZSh / (ZSh + ZBm1, 0)
(A65)
ZB1, 0 = Zmf1, 0 + CB1, 0 ZBm1, 0
(A66)
EBn =
(A67)
ZBm1, 0n =
(A68)
hn =
(A69)
δn = ∟EA - ∟EBn
ZA1 , 0= ZSA1, 0 + p ZL1, 0
ZB1, 0 =
+ ZmF1, 0 = ZBm1, 0n + ZmF1, 0
127
(A70)
(A71)
(A72)
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Figure (A2). The system circuit during fault (a) outside fault loops
(b) inside fault loop
The pre-fault current IApf can be calculated as follows:
–
IApf =
=
=
=
Kdn = 1- esh (1 – CB1) – CB1 h e
Eq (A73) is used to get the pre-fault voltage at point p.
VF0 = EA – IApf ZA1 =EA -
-jδ
(A74)
ZA1
= EA =
(A73)
ZA1
(
)
(
=
)
=
(A75)
Dn =
(A76)
CB1 =
(A77)
Ifa (1) =
(A78)
IAF (2) =
IAF
(0)
Ifa (1) = C1n Ifa (1)
=
Ifa
(1)
= C0n Ifa
(A79)
(1)
(A80)
KCL can be applied only on zero and negative sequence circuits only, but positive one has voltage sources. So we
will use KVL to get Ifa (1) in positive sequence circuit.
EA – EBn = IAf (1) ZA1 - IAf (1) ZBn1 = IAf (1) ZA1 - (Ifa (1) - IAf (1)) ZBn1
= IAf (1) [ZA1 + ZBn1] - Ifa (1) ZBn1
(A80)
IAf (1) = C1n Ifa (1) +
(A81)
=
=
x
IAf (1) = (Cdn + C1) Ifa (1)
128
= Cdn Ifa (1)
(A82)
(A83)
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Cdn =
(A84)
The compensated relay current is:
Irelay = (Cdn + 2C1n + C0n (1 + 3K0L)) Ifa (1)
Now we want to calculate the second quantity (voltage quantity) with the same technique used previously.
VA = VF + IAF (1) P ZL1 + IAF (2) P ZL1 + IAF (0) P ZL0
(A85)
= 3 RF Ifa (1) + P ZL1 [IAF (1) + IAF (2) + (1+3K0L) IAF (0)]
= 3 RF Ifa (1) + P ZL1 (Cdn +2C1n + (1 + 3K0L) C0n) Ifa (1)
Now we can get the relay measured impedance.
(A86)
Zrelay = PZL1 +
(A87)
CA1, 0 = ZSh / (ZSh + ZAm1, 0)
(A88)
ZA1, 0 = Zmf1, 0 + CA1, 0 ZAm1, 0
(A89)
A. 3.2. STATCOM Inside fault loop:
Following the same sequence in calculating fault current
CV =
(A90)
IAm (1) = CV Ifa (1) + CA1 Imf (1) = CV +CA1 (Cdn + C1) Ifa (1)
IAmc = [CV +CA1 (Cdn + 2C1) + CA0 C0 (1 + 3K0L)] Ifa
(1)
(A91)
(A92)
The relay voltage VA is driven as follows:
VA = VF +Imf Zmf1 + IAf mZL1
= 3 Ifa
(1)
RF + Zmf1 (Cdn + 2C1 +C0 (1 + 3K0L)) Ifa (1)
+ mZL1 (CV +CA1 (Cdn + 2C1) + C0 CA0 (1 + 3K0L) Ifa (1)
(A93)
Zmf1 (Cdn + 2C1 +C0 (1 + 3K0L)) =
Zmf1 (CV +CA1 (Cdn + 2C1) + C0 CA0 (1 + 3K0L))
+ Zmf1 (- CV + (1-CA1) (Cdn + 2C1) + C0 (1- CA0) (1 + 3K0L))
(A94)
VA = 3 Ifa (1) RF + pZL1 (CV +CA1 (Cdn + 2C1)
+ C0 CA0 (1 + 3K0L)) Ifa (1) + Csh Ifa (1)
(A95)
Csh = Zmf1 (- CV + (1-CA1) (Cdn + 2C1) + C0 (1- CA0) (1 + 3K0L) (A96)
From equations (A96) and (A93) by compensating the bus A current, we can get the relay measured impedance as
follows:
Zrelay = pZL1 +
(A97)
Where
Dn =ZAn1 + ZB1 – (CA1 + eSh (1 – CA1) – h e -jδ) (Cm ZAm1 + ZAn1)
(A98)
Cm =
(A99)
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130
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