An f p q droop control in cascaded-type microgrid
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In cascaded-type microgrid, the synchronization and power balance of distributed generators become two new issues that needs to be addressed urgently. To that end, an f-P/Q droop control is proposed in this letter, and its stability is analyzed as well. This proposed droop control is capable to achieve power balance under both resistive-inductive an resistive-capacitive loads autonomously. Compared with the inverse power factor droop control, an obvious advantage consists in extending the scope of application. Finally, the feasibility of the proposed method is verified by simulation results.
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This paper presents a binary topology of Multimodule level inverters produce a staircase output voltage from renewable DC voltage sources. The MLI (Multi Level Inverter) Requires many number of semiconductor switches is main drawback of multilevel inverters. The MLI can be classified as two method, one is symmetric and another asymmetric converters. In symmetrical multilevel inverter can apply same voltage level to all cascaded circuit, in asymmetric multilevel inverters can be vary input source voltage at each cascaded H-bridge by using binary algorithm. In this paper, a discrete binary topology for multilevel converters is proposed using cascaded sub-multilevel Cells. This sub-multilevel converter can produce sixty three levels of voltage from five discrete DC source. The Total Harmonic Distortions (THD) is minimized by discrete binary topology. The working operation and performance of the proposed multilevel inverters studies has been verified by simulation of using SIMULINK / MA TLAB results.
A Novel Design of PI Current Controller for PMSG-based Wind Turbine Consideri...
This paper presents a novel design process of decoupled PI current controller for permanent magnet synchronous generator (PMSG)-based wind turbines feeding a grid-tied inverter through back-to-back converter. Specifically, the design methodology consists of combining disturbance observer-based control (DOBC) with feedback linearization (FBL) technique to ensure nominal transient performance recovery under model uncertainty. By simplifying the DOBC under the feedback linearizing control, it is shown that the composite controller reduces to a decoupled PI current controller plus an additional term that has the main role of recovering the nominal transient performance of the feedback linearization, especially under step changes in the reference. Additionally, an anti windup compensator arises naturally into the controller when considering the control input saturation to design the DOBC. This permits to remove the effect of the saturation blocks required to limit the control input. The proposed control scheme is implemented and validated through experimentation conducted on 22-pole, 5 kW PMSG. The results revealed that the proposed technique can successfully achieve nominal performance recovery under model uncertainty as well as improved transient performances under control saturation.
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Development of wind and solar based ac microgrid with power quality improveme...
This work proposes a microgrid (μ-grid) integrating wind and solar photovoltaic (PV) resources, along with the battery energy storage (BES) to the three phase grid feeding the nonlinear load. The μ-grid disconcerted by probabilistic nonlinear time dependent parameters and their effects are compensated by cohesive controllers used for utility grid side voltage source converter (GVSC) and machine side VSC (MVSC). The switching controls and the reconfigurability of the μ-grid are addressed on imperative aspects of improving power quality (PQ), power reliability, nonlinear load compensation and economic utilization of resources. The nonlinear load compensation and PQ enhancement are achieved by executing modified version of the adaptive filtering technique including “momentum” based least mean square (MLMS) control technique, utilized for providing the switching control signals to the GVSC. It utilizes two preceding gradient weights for obtaining updated weight thereby improving the convergence rate and overcoming the limitation of conventional control of the same family. The MVSC acquires its switching signals from conventional vector control scheme and the encoderless estimation of speed and rotor position of the synchronous generator (SG) driven by wind turbine through back electromotive force control technique. The external environmental disturbances are overcome by utilizing perturb and observe (P&O) maximum power point (MPP) for wind optimal power extraction and adaptive P&O with variable perturbation step size for solar MPP estimation. Test results are obtained from the laboratory prototype under steady state and dynamic conditions including altering wind speed, intermittent solar insolation and variable load conditions. The PQ issues are addressed and investigated successfully.
Voltage sag enhancement of grid connected hybrid pv wind power system using b...
Renewable energy sources; which are abundant in nature and climate friendly are the only preferable choice of the world to provide green energy. The limitation of most renewable energy sources specifically wind and solar PV is its intermittent nature which are depend on wind speed and solar irradiance respectively and this leads to power fluctuations. To compensate and protect sensitive loads from being affected by the power distribution side fluctuations and faults, dynamic voltage restorer (DVR) is commonly used. This research work attempts to withstand and secure the effect of voltage fluctuation of grid connected hybrid PV-wind power system. To do so battery and super magnetic energy storage (SMES) based DVR is used as a compensating device in case of voltage sag condition. The compensation method used is a pre-sag compensation which locks the instantaneous real time three phase voltage magnitude and angle in normal condition at the point of common coupling (PCC) and stores independently so that during a disturbance it used for compensation. Symmetrical and asymmetrical voltage sags scenario are considered and compensation is carried out using Power System Computer Aided Design or Electro Magnetic Transient Design and Control (PSCAD/EMTDC) software.
Maximum power extraction from wind energy system based on fuzzy logic control
This paper proposes a variable speed control scheme for grid-connected wind energy conversion system (WECS) using permanent magnet synchronous generator (PMSG). The control algorithm tracks the maximum power for wind speeds below rated speed of wind turbines and ensures the power will not go over the rated power for wind speeds over the rated value. The control algorithm employs fuzzy logic controller (FLC) to effectively do this target. The wind turbine is connected to the grid via back-to-back PWM-VSC. Two effective computer simulation packages (PSIM and Simulink) are used to carry out the simulation effectively. The control system has two controllers for generator side and grid side converters. The main function of the generator side controller is to track the maximum power through controlling the rotational speed of the wind turbine using FLC. In the grid side converter, active and reactive power control has been achieved by controlling q-axis and d-axis current components, respectively. The d-axis current is set at zero for unity power factor and the q-axis current is controlled to deliver the power flowing from the dc-link to the electric utility grid.
A New Circuit of Modular Multilevel Inverter for Grid-Connected Photovoltaic ...
This study presents a new circuit topology of the Modular Multilevel Converter (MMC) which is deployed for photovoltaic grid applications. In the conventional MMC, two arm inductors are placed in each phase to limit the circulating current. In the proposed topology, the inductors are replaced by a transformer. The proposed circuit gives a 50% reduction of the voltage rating of the power devices and the capacitors in comparison with the conventional MMC. The required dc-link voltage which is fed directly by PV panels is also reduced by half. The paper presents a PWM method to control the solar inverter output voltage. The proposed concept is confirmed through simulation and experimental results.
Dual-function PV-ECS integrated to 3P4W distribution grid using 3M-PLL contro...
This study proposes a single-stage solar photovoltaic energy conversion system (PV-ECS) integrated to a three phase four-wire (3P4W) distribution grid with dual-function capabilities, i.e. active power transfer and power quality (PQ) enhancement at the point of interaction (PoI). The PV-ECS system comprises of a solar photovoltaic array and a voltage source inverter (VSI), supplying active power (during daytime) to the distribution grid and connected single-phase and three-phase loads. Apart from transfer of power, the system also improves the PQ at the PoI by compensating reactive power and neutral current, attenuating harmonics, correcting power factor and balancing grid currents. During night, the VSI acts as a shunt active power filter mitigating PQ issues, thereby increasing the device utilisation factor. A three-phase magnitude-phase locked loop (3M-PLL) method is utilised to extract and estimate fundamental term of load currents and an incremental conductance algorithm is applied for maximum power point tracking. To demonstrate its effectiveness, the system is modelled and its performance is simulated on MATLAB and experiments are performed on a developed prototype in the laboratory.
Control strategy for power flow management in a pv system supplying dc loads
The document describes a control strategy for managing power flow in a photovoltaic (PV) system that supplies both alternating current (AC) and direct current (DC) loads. A bidirectional converter and power management system direct power from the PV array, utility grid, and battery to meet load demands and regulate voltages. Experimental results on a laboratory prototype validated the control strategy's effectiveness in various operating modes and transient responses to load and solar irradiance changes.
Design and Control of Wind integrated Shunt Active Power Filter to Improve Po...
In this paper wind energy conservation system (WECS) with shunt active power filter (SAPF) is proposed for harmonics elimination, power factor correction, reactive power compensation and grid current balancing. Adaptive neuro fuzzy inference system (ANFIS) based controller is implemented at WECS side to control the boost converter to achieve MPP and at SAPF sides to minimize voltage variations and enhance power quality. Here, synchronous reference frame (SRF) theory based reference current generation technique is employed in SAPF. The proposed scheme is implemented in MATLAB/Simulink. The results confirm that this method has better performance and can maintain total harmonic distortion (THD) level of the system within the IEEE standard 519.
A Unified Control and Power Management Scheme for PV-Battery-Based Hybrid Mic...
This document describes a control and power management system (CAPMS) for PV-battery hybrid microgrids. The CAPMS can regulate DC and AC voltages and frequencies, control unit voltages and power flexibly, and balance power flows under different operating conditions, including switching between grid-connected and island modes. Both simulations and experiments validate that the CAPMS provides stable voltage for loads despite disturbances. The CAPMS is presented as a way to manage hybrid microgrid power flows effectively and realize balanced power between the microgrid and grid.
A PWM Strategy Based on State Transition for Cascaded H-Bridge Inverter under...
Cascaded H-bridge converter has been widely used and researched in industry, since it is suitable for the operation under both normal and fault conditions. This paper proposes a novel PWM strategy based on state transition for cascaded H-Bridge inverter with unbalanced DC sources to achieve high quality line-to-line output voltages and maximize the linear modulation range. In this modulation strategy, the duration time of each switching state will be modified directly through the correction value. Ranges of correction value are derived by analyzing the modulation index limitation. Then, proper correction value is added into duration times to transform the switching states and extend modulation index to the maximum value. Meanwhile, balanced AC currents can be obtained under unbalanced DC sources condition, even under larger unbalanced coefficients. Furthermore, a three-phase power control algorithm (PCA) is introduced to achieve the balanced distribution of three-phase power. Compared with the traditional zero-sequence voltage injection method, the proposed strategy is more convenient and effective theoretically, and it can be applied to the higher-level cascaded H-bridge converter. The advantage and effectiveness of the proposed strategy are verified by simulation and experiment results.
Voltage Sag and Swell Mitigation Using DSTATCOM in Renewable Energy Based Dis...
Renewable distributed generation systems are an alternative solution to provide energy locally near customers. However, the supplying of power without disturbance is the main challenge for utilities, especially for systems that integrate fluctuating renewable sources which can cause voltage sag and swell. In this paper, voltage sag and swell issues are investigated. The first studied scenario is related to the disturbance of the energy source and the second one is due to the installation of a heavy load with a sensitive load at the same supplying bus. A D-STATCOM is connected at the point of common coupling (pCC) to mitigate the voltage sag and sell problems. An energy storage battery has been installed at the DC-side of the compensator that gives the possibility to control the voltage at the PCC and exchange the active and reactive power with the grid. A linear proportional integral (PI) feed-forward controller supervises the compensator. The obtained results show that the D-STATCOM compensator behaves as a good solution to mitigate the voltage sag and swell in distribution grid.
Model predictive control of pv sources in a smart dc distribution system maxi...
In a dc distribution system, where multiple power sources supply a common bus, current sharing is an important issue. When renewable energy resources are considered, such as photovoltaic (PV), dc/dc converters are needed to decouple the source voltage, which can vary due to operating conditions and maximum power point tracking (MPPT), from the dc bus voltage. Since different sources may have different power delivery capacities that may vary with time, coordination of the interface to the bus is of paramount importance to ensure reliable system operation. Further, since these sources are most likely distributed throughout\ the system, distributed controls are needed to ensure a robust and fault tolerant control system. This paper presents a model predictive control-based MPPT and model predictive control-based droop current regulator to interface PV in smart dc distribution systems. Back-to-back dc/dc converters control both the input current from the PV module and the droop characteristic of the output current injected into the distribution bus. The predictive controller speeds up both of the control loops, since it predicts and corrects error before the switching signal is applied to the respective converter.
A Simplified Space Vector Pulse-Width Modulation Scheme for Three-Phase Casca...
This document presents a simplified space vector pulse-width modulation (SVPWM) scheme for three-phase cascaded H-bridge inverters. It treats each unit as a three-level inverter and uses three-level SVPWM to modulate each unit individually. Duty cycles from sector 1 are mapped to obtain duty cycles for other sectors. This simplifies the process compared to conventional multilevel SVPWM. Simulation and experimental results validate the presented SVPWM scheme, which provides a higher effective switching frequency while maintaining the same DC-link voltage utilization as conventional SVPWM, with significantly reduced FPGA resource utilization.
Critical Current Control (C3) and Modeling of a Buck Based LED Driver with Po...
Buck converter has a good aptitude for LED driver application. Here a new technique introduced to control and model a buck converter in the closed loop condition using Lagrange equation. To improve the final model accuracy, parasitic elements of the converter are taken into account. The main advantage of this method is its novelty and simple implementation. Also, the converter power factor has improved under critical current control (C3) technique. Frequency response and step response of the small signal model are derived and analysed. The theoretical predictions are tested and validated by means of PSIM software. Finally, precise agreement between the proposed model and the simulation results has obtained.
A New Switched-Capacitor Five-Level Inverter Suitable for Transformerless Gri...
Transformerless grid-connected inverters have been extensively popular in renewable energy-based applications owing to some interesting features like higher efficiency, reasonable cost and acceptable power density. The major concern of such converters is the leakage current problem and also the step-down feature of the output voltage which causes a costly operation for a single stage energy conversion system. A new five-level transformerless inverter topology is presented in this study, which is able to boost the value of the input voltage and can remove the leakage current problem through a common-grounded architecture. Here, providing the five-level of the output voltage with only six power switches is facilitated through the series-parallel switching of a switched-capacitor module. Regarding this switching conversion, the self- voltage balancing of the integrated capacitors over a full cycle of the grid’s frequency can be acquired. Additionally, to inject a tightly controlled current to the local grid, a peak current controller-based technique is employed, which can regulate both the active and reactive power support modes. Theoretical analyses besides some experimental results are also given to corroborate the correct performance of the proposed topology.
Comparison of Modulation Techniques for Matrix Converter
Matrix Converters can directly convert an ac power supply of fixed voltage into an ac voltage of variable amplitude and frequency. Matrix Converter is a single stage converter. The matrix converters can contribute to the realization of low volume, sinusoidal input current, bidirectional power flow and lack of bulky reactive elements. All the reasons lead to the development of matrix converter. Based on the control techniques used in the matrix converter, the performance varies. So this paper analyses the performance of matrix converter with three different modulation techniques such as PWM, SVPWM and SVM. The basic principle and switching sequence of these modulation techniques are presented in this paper. The output voltage, output current waveforms, voltage transfer ratio and THD spectrum of switching waveforms connected to RL load are analyzed by using Matlab/Simulink software. The simulated results are analyzed and show that the THD is better for SVM technique.
Maximum power point tracking using fuzzy logic controller under partial condi...
This document describes a study that proposes a fuzzy logic controller for tracking the maximum power point of a photovoltaic system under different conditions. A MATLAB/Simulink model is developed that includes a PV panel, boost converter, and fuzzy logic-based MPPT algorithm. The fuzzy controller is shown to successfully track the MPP under uniform irradiation, sudden changes in irradiation, and partial shading conditions. Simulation results demonstrate the advantages of the fuzzy logic approach over conventional MPPT methods.
Novel symmetric modular hybrid multilevel inverter with reduced number of sem...
In this paper, by using a modular hybrid structure, a new topology for symmetric multilevel inverters (MLI) with a small number of semiconductors and low voltage stress across switches is proposed. Despite many other topologies, this topology can inherently produce negative levels and zero levels without using the H-bridge. The voltage stress across a particular switch of the proposed MLI is inversely proportional to the number of the switching of that switch in a voltage period. The proposed structure is based on two types of module, that is, the f-module and the e-module. The e-module uses a capacitive voltage divider to double the number of non-zero levels. The voltages of the capacitors are approximately balanced without complex control methods. The basic structure of the proposed topology is formed by connecting the f-module and the e-module in series with each other, and the cascaded topology is developed by cascading multiple f-modules with an e-module. To investigate the proposed topology and proving its practicability, simulation results with MATLAB/Simulink, investigation of the capacitor voltages, loss calculations and experimental results are presented. A comparative study is also performed to show the merit of the new multilevel inverter over other topologies.
Power management strategy for a multi hybrid fuel cell energy storage power ...
This paper depicts a new configuration for modular hybrid power conversion systems, namely, multi-hybrid generation system (MHGS), and parallel connection at the output, such that the converter of each unit shares the load current equally. This is a significant step towards realizing a modular power conversion system architecture, where smaller units can be connected in any series/parallel grouping to realize any required unit specifications. The supercapacitor (SC) as a complementary source is used to compensate for the slow transient response of the fuel cell (FC) as a main power source. It assists the Fe to meet the grid power demand in order to achieve a better performance and dynamic behavior. Reliable control of the proposed MHGS with multiple units is also a challenging issue. In this paper, a simple control method to achieve active sharing of load current among MHGS modules is proposed. The simulation results verify the performance of the proposed structure and control scheme.
Solar grid tied inverter, with battery back-up, for efficient solar energy ha...
Solar Grid-Tied Inverter system is an electricity generating system that is connected to the utility grid. This paper discusses the design of a Grid-Tied Inverter (GTI). The first stage is Maximum Power Point Tracking (MPPT) which is implemented using perturb and observe algorithm. Then push pull converter is used to convert DC output from MPPT stage to 330V dc. This DC voltage is then converted into AC voltage using full-wave inverter topology employing unipolar SPWM technique. Then synchronization is achieved between grid and photovoltaic system. Finally, power flow control mechanism controls the power flow from GTI system to the grid and the house load.
Sensorless bldc motor commutation point detection and phase deviation correct...
This document discusses electrical projects using MATLAB/Simulink that focus on improving energy efficiency. It describes a project to replace a conventional induction motor with a brushless DC motor to power a 5000 m3/h commercial evaporative cooler. Experimental results showed the brushless motor improved efficiency by at least 75% compared to the induction motor, improving the energy rating from IE1 to IE5. It also proposes a constant power control method to maintain airflow in the face of pressure differences, and confirms this method was effective through testing. The document provides contact information for those interested in simulation results.
What's hot (20)
Development of wind and solar based ac microgrid with power quality improveme...
Development of wind and solar based ac microgrid with power quality improveme...
Voltage sag enhancement of grid connected hybrid pv wind power system using b...
Voltage sag enhancement of grid connected hybrid pv wind power system using b...
Maximum power extraction from wind energy system based on fuzzy logic control
Maximum power extraction from wind energy system based on fuzzy logic control
A New Circuit of Modular Multilevel Inverter for Grid-Connected Photovoltaic ...
A New Circuit of Modular Multilevel Inverter for Grid-Connected Photovoltaic ...
Dual-function PV-ECS integrated to 3P4W distribution grid using 3M-PLL contro...
Dual-function PV-ECS integrated to 3P4W distribution grid using 3M-PLL contro...
Control strategy for power flow management in a pv system supplying dc loads
Control strategy for power flow management in a pv system supplying dc loads
Design and Control of Wind integrated Shunt Active Power Filter to Improve Po...
Design and Control of Wind integrated Shunt Active Power Filter to Improve Po...
A Unified Control and Power Management Scheme for PV-Battery-Based Hybrid Mic...
A Unified Control and Power Management Scheme for PV-Battery-Based Hybrid Mic...
A PWM Strategy Based on State Transition for Cascaded H-Bridge Inverter under...
A PWM Strategy Based on State Transition for Cascaded H-Bridge Inverter under...
Voltage Sag and Swell Mitigation Using DSTATCOM in Renewable Energy Based Dis...
Voltage Sag and Swell Mitigation Using DSTATCOM in Renewable Energy Based Dis...
Model predictive control of pv sources in a smart dc distribution system maxi...
Model predictive control of pv sources in a smart dc distribution system maxi...
A Simplified Space Vector Pulse-Width Modulation Scheme for Three-Phase Casca...
A Simplified Space Vector Pulse-Width Modulation Scheme for Three-Phase Casca...
Critical Current Control (C3) and Modeling of a Buck Based LED Driver with Po...
Critical Current Control (C3) and Modeling of a Buck Based LED Driver with Po...
A New Switched-Capacitor Five-Level Inverter Suitable for Transformerless Gri...
A New Switched-Capacitor Five-Level Inverter Suitable for Transformerless Gri...
Comparison of Modulation Techniques for Matrix Converter
Comparison of Modulation Techniques for Matrix Converter
Maximum power point tracking using fuzzy logic controller under partial condi...
Maximum power point tracking using fuzzy logic controller under partial condi...
Novel symmetric modular hybrid multilevel inverter with reduced number of sem...
Novel symmetric modular hybrid multilevel inverter with reduced number of sem...
Power management strategy for a multi hybrid fuel cell energy storage power ...
Power management strategy for a multi hybrid fuel cell energy storage power ...
Solar grid tied inverter, with battery back-up, for efficient solar energy ha...
Solar grid tied inverter, with battery back-up, for efficient solar energy ha...
Sensorless bldc motor commutation point detection and phase deviation correct...
Sensorless bldc motor commutation point detection and phase deviation correct...
Similar to An f p q droop control in cascaded-type microgrid
Hybrid topology of asymmetric cascaded multilevel inverter with renewable ene...
This paper presents a binary topology of Multimodule level inverters produce a staircase output voltage from renewable DC voltage sources. The MLI (Multi Level Inverter) Requires many number of semiconductor switches is main drawback of multilevel inverters. The MLI can be classified as two method, one is symmetric and another asymmetric converters. In symmetrical multilevel inverter can apply same voltage level to all cascaded circuit, in asymmetric multilevel inverters can be vary input source voltage at each cascaded H-bridge by using binary algorithm. In this paper, a discrete binary topology for multilevel converters is proposed using cascaded sub-multilevel Cells. This sub-multilevel converter can produce sixty three levels of voltage from five discrete DC source. The Total Harmonic Distortions (THD) is minimized by discrete binary topology. The working operation and performance of the proposed multilevel inverters studies has been verified by simulation of using SIMULINK / MA TLAB results.
A Novel Design of PI Current Controller for PMSG-based Wind Turbine Consideri...
This paper presents a novel design process of decoupled PI current controller for permanent magnet synchronous generator (PMSG)-based wind turbines feeding a grid-tied inverter through back-to-back converter. Specifically, the design methodology consists of combining disturbance observer-based control (DOBC) with feedback linearization (FBL) technique to ensure nominal transient performance recovery under model uncertainty. By simplifying the DOBC under the feedback linearizing control, it is shown that the composite controller reduces to a decoupled PI current controller plus an additional term that has the main role of recovering the nominal transient performance of the feedback linearization, especially under step changes in the reference. Additionally, an anti windup compensator arises naturally into the controller when considering the control input saturation to design the DOBC. This permits to remove the effect of the saturation blocks required to limit the control input. The proposed control scheme is implemented and validated through experimentation conducted on 22-pole, 5 kW PMSG. The results revealed that the proposed technique can successfully achieve nominal performance recovery under model uncertainty as well as improved transient performances under control saturation.
Power Quality Assessment of Voltage Positive Feedback Based Islanding Detecti...
Islanding refers to a condition where distributed generators (DGs) inject power solely to the local load after electrical separation from power grid. Several islanding detection methods (IDMs) categorized into remote, active, and passive groups have been reported to detect this undesirable state. In active techniques, a disturbance is injected into the DG’s controller to drift a local yardstick out of the permissible range. Although this disturbance leads to more effective detections even in well-balanced island, it raises the total harmonic distortion (THD) of the output current under the normal operation conditions. This paper analyzes the power quality aspect of the modified sliding mode controller as a new active IDM for grid-connected photovoltaic system (GCPVS) with a string inverter. Its performance is compared with the voltage positive feedback (VPF) method, a well-known active IDM. This evaluation is carried out for a 1 kWp GCPVS in MATLAB/Simulink platform by measuring the output current harmonics and THD as well as the efficiency under various penetration and disturbance levels. The output results demonstrate that since the proposed disturbance changes the amplitude of the output current, it does not generate harmonics/subharmonics. Thereby, it has a negligible adverse effect on power quality. It is finally concluded that the performance of the sliding mode-based IDM is reliable from the standpoints of islanding detection and power quality.
Novel High Performance Stand Alone Solar PV System with High Gain, High Effic...
This document describes a novel standalone solar PV system that uses high gain, high efficiency DC-DC converters in both the power stage and battery interface. This allows the use of low voltage PV and battery sources while minimizing issues from partial shading. It also prevents overcharging and deep discharging of battery modules. The system facilitates "required power tracking" from the PV source to match load requirements without needing dump loads. Simulation and experimental results show the system achieves high performance and efficiency of 94%. The document concludes by noting limitations and opportunities for further improvement.
A simplified phase shift pwm-based feedforward distributed mppt method for gr...
The modularity and decreased filter size properties have made cascaded multilevel inverters (MLIs) more applicable than conventional two-level inverters, especially in high and medium power photovoltaic (PV) applications. However, partial shading of PV modules will affect negatively the output power of the unshaded modules. There are several existing solutions in the literature to address this challenge, however almost all of them suffer from complex implementations, low efficiency, and high cost. This paper presents a new simplified feedforward distributed maximum power point tracking (MPPT) method for three-phase grid-connected cascaded MLIs. The cascaded MLI provides a modular, and highly efficient single stage power conversion for PV systems. The proposed distributed MPPT method is depending on the phase-shift pulse width modulation (PSPWM) method with a simplified implementation. The proposed method is developing a feedforward signal that is proportional to the maximum power of the individual module. Then, the current controller, and the modulating signal are multiplied with the proportionality factor of the module maximum power. Furthermore, a modified modulation compensation method without using proportional-integral (PI) controllers is introduced to solve the problem of the unbalanced three-phase PV output currents that results from PV power mismatches and shading. A case study is implemented for 15 kW PV system to investigate the performance of the proposed method. In addition, comprehensive comparisons with the previous attempts in the literature are provided to verify the superior performance of the new proposed control method.
Mppt with single dc–dc converter and inverter for grid connected hybrid wind-...
This document describes a new hybrid distributed generator system that uses a photovoltaic array and permanent magnet synchronous generator driven by wind to generate power. The system uses a single boost converter and inverter to connect the sources to the grid, requiring fewer power converters than previous schemes. MATLAB/Simulink is used to model and simulate the system. Low-cost controllers are proposed for the boost converter and inverter to independently track the maximum power from each source. Simulation and experimental results demonstrate the successful operation and performance of the new hybrid system.
Power Quality Assessment of Voltage Positive Feedback Based Islanding Detecti...
Islanding refers to a condition where distributed generators (DGs) inject power solely to the local load after electrical separation from power grid. Several islanding detection methods (IDMs) categorized into remote, active, and passive groups have been reported to detect this undesirable state. In active techniques, a disturbance is injected into the DG’s controller to drift a local yardstick out of the permissible range. Although this disturbance leads to more effective detections even in well-balanced island, it raises the total harmonic distortion (THD) of the output current under the normal operation conditions. This paper analyzes the power quality aspect of the modified sliding mode controller as a new active IDM for grid-connected photovoltaic system (GCPVS) with a string inverter. Its performance is compared with the voltage positive feedback (VPF) method, a well-known active IDM. This evaluation is carried out for a 1 kWp GCPVS in MATLAB/Simulink platform by measuring the output current harmonics and THD as well as the efficiency under various penetration and disturbance levels. The output results demonstrate that since the proposed disturbance changes the amplitude of the output current, it does not generate harmonics/subharmonics. Thereby, it has a negligible adverse effect on power quality. It is finally concluded that the performance of the sliding mode-based IDM is reliable from the standpoints of islanding detection and power quality.
A Dual Control Strategy for Power Sharing Improvement In Islanded Mode of AC ...
Parallel operation of inverter modules is the solution to increase the reliability, efficiency, and redundancy of inverters in microgrids. Load sharing among inverters in distributed generators (DGs) is a key issue. This study investigates the feasibility of power-sharing among parallel DGs using a dual control strategy in islanded mode of a microgrid. PQ control and droop control techniques are established to control the microgrid operation.
Dynamic behavior of DFIG wind turbine under grid fault conditions (1)
The document discusses the dynamic behavior of a doubly fed induction generator (DFIG) wind turbine system under grid fault conditions. It presents a detailed MATLAB/Simulink model of a DFIG wind turbine that includes a vector control technique. Simulation results are shown for the DFIG's performance under normal and abnormal grid conditions, including plots of stator currents, rotor currents, speed and torque, and active and reactive power. The conclusion is that the DFIG control is satisfactory under normal conditions but its response needs to be investigated under grid faults and disturbances.
An advanced multilevel converter topology with Reduced switching elements
Smart grid applications, renewable energy utilization and electric vehicles (EVs) are attracting researchers due to their importance nowadays as well as in the future. An efficient power electronic converter is a main and common topic for research in this area. In this paper, a prototype of the electrical part of a power-train for EVs using an advanced multilevel converter topology is introduced, discussed and analysed. A comparison between the advanced converter, two-level and conventional multilevel converter topology is discussed as well. A switch function model is derived and discussed for the proposed converter. A mathematical model for the converter supplied by a fuel-cell (FC) and boost-converter (BC) is implemented with Matlab/Simulink. The simulation results are analysed to evaluate the converter. The evaluation is based on the harmonic analysis and power loss calculations. The converters are tested at different switching frequencies to show the effect of this variable on the converter loss. The results indicate that the proposed converter is 1.32% more efficient compared to conventional five-level DCC. Moreover, the lowest harmonic content, for all of the studied converters, is the proposed one
Adaptive pi control of statcom for voltage regulation
STATCOM can provide fast and efficient reactive power support to maintain power system voltage stability. In the literature, various STATCOM control methods have been discussed including many applications of proportional-integral (PI) controllers. However, these previous works obtain the PI gains via a trial-and-error approach or extensive studies with a tradeoff of performance and applicability. Hence, control parameters for the optimal performance at a given operating point may not be effective at a different operating point. This paper proposes a new control model based on adaptive PI control, which can self-adjust the control gains during a disturbance such that the performance always matches a desired response, regardless of the change of operating condition. Since the adjustment is autonomous, this gives the plug-and-play capability for STATCOM operation. In the simulation test, the adaptive PI control shows consistent excellence under various operating conditions, such as different initial control gains, different load levels, change of transmission network, consecutive disturbances, and a severe disturbance. In contrast, the conventional STATCOM control with tuned, fixed PI gains usually perform fine in the original system, but may not perform as efficient as the proposed control method when there is a change of system conditions.
Permanent Magnet Synchronous Generator-Based Standalone Wind Energy Supply Sy...
In this paper, a novel algorithm, based on dc link voltage, is proposed for effective energy management of a standalone permanent magnet synchronous generator (PMSG)-based variable speed wind energy conversion system consisting of battery, fuel cell, and dump load (i.e., electrolyzer). Moreover, by maintaining the dc link voltage at its reference value, the output ac voltage of the inverter can be kept constant irrespective of variations in the wind speed and load. An effective control technique for the inverter, based on the pulse width modulation (PWM) scheme, has been developed to make the line voltages at the point of common coupling (PCC) balanced when the load is unbalanced. Similarly, a proper control of battery current through dc–dc converter has been carried out to reduce the electrical torque pulsation of the PMSG under an unbalanced load scenario. Based on extensive simulation results using MATLAB/SIMULINK, it has been established that the performance of the controllers both in transient as well as in steady state is quite satisfactory and it can also maintain maximum power point tracking.
Power Management in PV-Battery-Hydro Based Standalone Microgrid
This paper proposes a high-efficiency two stage three-level grid-connected photovoltaic inverter. This work deals with the frequency regulation, voltage regulation, power management and load levelling of solar photovoltaic (PV)-battery-hydro based microgrid (MG). In this MG, the battery capacity is reduced as compared to a system, where the battery is directly connected to the DC bus of the voltage source converter (VSC). A bidirectional DC–DC converter connects the battery to the DC bus and it controls the charging and discharging current of the battery. It also regulates the DC bus voltage of VSC, frequency and voltage of MG. The proposed system manages the power flow of different sources like hydro and solar PV array. However, the load levelling is managed through the battery. The battery with VSC absorbs the sudden load changes, resulting in rapid regulation of DC link voltage, frequency and voltage of MG. Therefore, the system voltage and frequency regulation allows the active power balance along with the auxiliary services such as reactive power support, source current harmonics mitigation and voltage harmonics reduction at the point of common interconnection. The experimental results under various steady state and dynamic conditions, exhibit the excellent performance of the proposed system and validate the design and control of proposed MG.
Single-Stage Power-Factor-Correction Circuit with Flyback Converter to Drive ...
White light emitting diode (LED) with high brightness has attracted a lot of attention from both
industry and academia for its high efficiency, ease to drive, environmental friendliness, and long
lifespan. They become possible applications to replace the incandescent bulbs and fluorescent
lamps in residential, industrial and commercial lighting. The realization of this new lighting
source requires both tight LED voltage regulation and high power factor as well. This paper
proposed a single-stage flyback converter for the LED lighting applications and input power
factor correction. A type-II compensator has been inserted in the voltage loop providing
sufficient bandwidth and stable phase margin. The flyback converter is controlled with voltage
mode pulse width modulation (PWM) and run in discontinuous conduction mode (DCM) so that
the inductor current follows the rectified input voltage, resulting in high power factor. A
prototype topology of closed-loop, single stage flyback converter for LED driver circuit designed
for an 18W LED lighting source is constructed and tested to verify the theoretical predictions.
The measured performance of the LED lighting fixture can achieve a high power factor greater
than 0.998 and a low total harmonic distortion less than 5.0%. Experimental results show the
functionality of the overall system and prove it to be an effective solution for the new lighting
applications.
Designing of Multilevel DPFC to Improve Power Quality
According to growth of electricity demand and the increased number of non-linear loads in power grids, providing a high quality electrical power should be considered. In this paper, Enhancement of power quality by using fuzzy based multilevel power flow controller (DPFC) is proposed. The DPFC is a new FACTS device, which its structure is similar to unified power flow controller (UPFC). In spite of UPFC, in DPFC the common dc-link between the shunt and series converters is eliminated and three-phase series converter is divided to several single-phase series distributed converters through the line. This eventually enables the DPFC to fully control all power system parameters. It, also, increases the reliability of the device and reduces its cost simultaneously. In recent years multi level inverters are used high power and high voltage applications .Multilevel inverter output voltage produce a staircase output waveform, this waveform look like a sinusoidal waveform leads to reduction in Harmonics. Fuzzy Logic is used for optimal designing of controller parameters. Application of Fuzzy Multilevel DPFC for reduction of Total Harmonic Distortion was presented. The simulation results show the improvement of power quality using DPFC with Fuzzy logic controller.
Control for Grid-Connected and Intentional Islanding Operations of Distribute...
Intentional islanding describes the condition in which a microgrid or a portion of the power grid,
which consists of a load and a distributed generation (DG) system, is isolated from the remainder
of the utility system. In this situation, it is important for the microgrid to continue to provide
adequate power to the load. Under normal operation, each DG inverter system in the microgrid
usually works in constant current control mode in order to provide a preset power to the main
grid. When the microgrid is cut off from the main grid, each DG inverter system must detect this
islanding situation and must switch to a voltage control mode. In this mode, the microgrid will
provide a constant voltage to the local load. This paper describes a control strategy that is used to
implement grid-connected and intentional-islanding operations of distributed power generation.
This paper proposes an intelligent load-shedding algorithm for intentional islanding and an
algorithm of synchronization for grid reconnection.
Simulation and analysis of perturb and observe mppt algorithm for array using...
This paper presents the comparative analysis between constant duty cycle and Perturb & Observe (P&O) algorithm for extracting the power from Photovoltaic Array (PVA). Because of nonlinear characteristics of PV cell, the maximum power can be extract under particular voltage condition. Therefore, Maximum Power Point Tracking (MPPT) algorithms are used in PVA to maximize the output power. In this paper the MPPT algorithm is implemented using Ćuk converter. The dynamics of PVA is simulated at different solar irradiance and cell temperature. The P&O MPPT technique is a direct control method enables ease to implement and less complexity.
Modified cascaded h bridge multilevel inverter for hybrid renewable energy ap...
Renewable energy sources and technologies have the potential to provide solutions to the longstanding energy problems being faced by developing countries. The renewable energy sources like wind energy, solar energy, geothermal energy, ocean energy, biomass energy and fuel cell technology can be used to overcome energy shortage in India. This paper proposes a modified multi-level inverter (MLI) topology for Hybrid Renewable Energy Sources (HRES) and a design of hybrid solar-wind power generation model with 9-level, 13-level and 17-level inverter topologies. A HRES connected to a modified Cascaded H-Bridge Multi Level Inverter (CHB-MLI) is developed, whose switches are controlled using Artificial Neural Network (ANN) model. The proposed hybrid energy system model consists of 10 Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) that intend to give 17 levels of output voltage. The proposed topology performs effectively with reduced number of components and reduced Total Harmonic Distortion (THD). The performance of the proposed system is analyzed by designing the model in MATLAB/SIMULINK environment. The simulation results of the proposed inverter for the HRES application are compared with the results of the existing topologies to show the effectiveness of the proposed model.
New ac dc power factor correction architecture suitable for high frequency op...
This paper presents a novel ac-dc power factor correction (PFC) power conversion architecture for single-phase grid interface. The proposed architecture has significant advantages for achieving high efficiency, good power factor, and converter miniaturization, especially in low-to-medium power applications. The architecture enables twice-line-frequency energy to be buffered at high voltage with a large voltage swing, enabling reduction in the energy buffer capacitor size, and elimination of electrolytic capacitors. While this architecture can be beneficial with a variety of converter topologies, it is especially suited for system miniaturization by enabling designs that operate at high frequency (HF, 3 – 30 MHz). Moreover, we introduce circuit implementations that provide efficient operation in this range. The proposed approach is demonstrated for an LED driver converter operating at a (variable) HF switching frequency (3 – 10 MHz) from 120Vac, and supplying a 35Vdc output at up to 30W. The prototype converter achieves high efficiency (92 %) and power factor (0.89), and maintains good performance over a wide load range. Owing to architecture and HF operation, the prototype achieves a high ‘box’ power density of 50W/ in3 (‘displacement’ power density of 130W/ in3), with miniaturized inductors, ceramic energy buffer capacitors, and a small-volume EMI filter.
High frequency ac-link pv inverter
In this paper, a high-frequency ac-link photovoltaic (PV) inverter is proposed. The proposed inverter overcomes most of the problems associated with currently available PV inverters. In this inverter, a single-stage power-conversion unit fulfills all the system requirements, i.e., inverting dc voltage to proper ac, stepping up or down the input voltage, maximum power point tracking, generating low-harmonic ac at the output, and input/output isolation. This inverter is, in fact, a partial resonant ac-link converter in which the link is formed by a parallel inductor/capacitor (LC) pair having alternating current and voltage. Among the significant merits of the proposed inverter are the zero-voltage turn-on and soft turn-off of the switches which result in negligible switching losses and minimum voltage stress on the switches. Hence, the frequency of the link can be as high as permitted by the switches and the processor. The high frequency of operation makes the proposed inverter very compact. The other significant advantage of the proposed inverter is that no bulky electrolytic capacitor exists at the link. Electrolytic capacitors are cited as the most unreliable component in PV inverters, and they are responsible for most of the inverters’ failures, particularly at high temperature. Therefore, substituting dc electrolytic capacitors with ac LC pairs will significantly increase the reliability of PV inverters. A 30-kW prototype was fabricated and tested. The principle of operation and detailed design procedure of the proposed inverter along with the simulation and experimental results are included in this paper. To evaluate the long-term performance of the proposed inverter, three of these inverters were installed at three different commercial facilities in Texas, USA, to support the PV systems. These inverters have been working for several months now.
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Power Quality Assessment of Voltage Positive Feedback Based Islanding Detecti...
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A Dual Control Strategy for Power Sharing Improvement In Islanded Mode of AC ...
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An advanced multilevel converter topology with Reduced switching elements
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Adaptive pi control of statcom for voltage regulation
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Permanent Magnet Synchronous Generator-Based Standalone Wind Energy Supply Sy...
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Power Management in PV-Battery-Hydro Based Standalone Microgrid
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Single-Stage Power-Factor-Correction Circuit with Flyback Converter to Drive ...
Single-Stage Power-Factor-Correction Circuit with Flyback Converter to Drive ...
Designing of Multilevel DPFC to Improve Power Quality
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Control for Grid-Connected and Intentional Islanding Operations of Distribute...
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More from Asoka Technologies
Solar pv charging station for electric vehicles
This document describes a project to design and simulate a solar photovoltaic charging station for electric vehicles using MATLAB/Simulink. The charging station employs a multi-port design to provide constant voltage DC power from the solar panels to charge vehicle batteries using a constant current/constant voltage method. The performance of the charging system is validated through simulation and experimental results. The conclusion discusses opportunities to enhance such systems through optimization techniques, energy storage, intelligent controllers, and hybrid designs incorporating multiple renewable energy sources.
Generation of Higher Number of Voltage Levels by Stacking Inverters of Lower ...
This paper proposes a new method of generating higher number of levels in the voltage waveform by stacking multilevel converters with lower voltage space vector structures. An important feature of this stacked structure is the use of low voltage devices while attaining higher number of levels. This will find extensive applications in electric vehicles since direct battery drive is possible. The voltages of all the capacitors in the structure can be controlled within a switching cycle using the switching state redundancies (pole voltage redundancies). This helps in reducing the capacitor size. Also, the capacitor voltages can be balanced irrespective of modulation index and load power factor. To verify the concept experimentally, a 9-level inverter is developed by stacking two 5-level inverters and an induction motor is run using V/f control scheme. Both steady state and transient results are presented.
A Variable DC Link based Novel Multilevel Inverter Topology for Low Voltage A...
In this paper; a variable dc link based novel multilevel inverter (MLI) topology is proposed. This proposed topology comprises two variable dc links and a modified H-bridge unit. This new single-phase topology offers advantages such as reduction in count of switches; gate drivers and dc sources while simultaneously improving the power quality. The proposed topology has been analyzed for both symmetric and asymmetric modes of operation. A comparative study of the proposed topology with some recent MLI topologies has been presented. The comparative study indicates that the proposed topology requires less number of dc sources; switches and driver circuits as compared to other topologies. The proposed topology has been simulated for 31- level asymmetric configuration in MATLAB/SIMULINK environment to verify the proper operation of proposed topology. Harmonic analysis was also performed for 31-level inverter which showed significant reduction in the total harmonic distortion (THD) for phase voltage and current waveforms. The proposed topology is suitable for low voltage applications such as standalone photovoltaic (PV) systems and hybrid electric vehicles (HEVs).
A New Family of Step-up Hybrid Switched- Capacitor Integrated Multilevel Inve...
In the low voltage based renewable systems like PV and Fuel cell applications, the step-up of the output voltage to drive the loads is essential. For this, the integration of switched-capacitor (SC) units with the dc-ac converters will have the potential advantages like improved efficiency, optimal switching devices, small size of passive elements (L and C) as compared with traditional two-stage conversion system (dc/dc converter and dc/ac converter). This paper focuses on a new family of step-up multilevel inverter topologies with switched capacitor integration with dual input voltage sources. With the flexibility of 2 dc sources and switching capacitor circuits, four different topologies have been suggested in this paper with features of high voltage gain, reduced component count, reduced voltage stress and self-voltage balancing of the capacitor while achieving a higher number of levels. A detailed analysis of proposed multilevel inverters has been analyzed with the symmetrical and asymmetrical mode of operations and the associated gain, the number of levels, and other performance indices are presented. An in-depth study of all the topologies has been accomplished in this paper with several comparative studies in terms of components count, voltage gain and cost. The effectiveness and practicability of the suggested topology with 13 level output voltage has been explained by the experimental results obtained from a scale down prototype.
A multi cell 21-level hybrid multilevel inverter synthesizes a reduced number...
A multi-cell hybrid 21-Level multilevel inverter is proposed in this paper. The proposed topology includes two-unit; an H-bridge is cascaded with a modified K-type unit to generate an output voltage waveform with 21 levels based only on two unequal DC suppliers. The proposed topology's advantage lies in the fine and clear output voltage waveforms with high output efficiency. Meanwhile, the high number of output voltage waveform levels generates a low level of distortion and reduces the level of an electromagnetic interface (EMI). Moreover, it reduces the voltage stress on the switching devices and gives it a long lifetime. Also, the reduction in the number of components has a noticeable role in saving size and cost. Regarding the capacitors charging, the proposed topology presents an online method for charging and balancing the capacitor's voltage without any auxiliary circuits. The proposed topology can upgrade to a high number of output steps through the cascading connection. Undoubtedly this cascading will increase the power level to medium and high levels and reduce the harmonics content to a neglectable rate. The proposed system has been tested through the simulation results, and an experimental prototype based on the controller dSPACE (DS-1103) hardware unit used to support the simulation results.
A generalized multilevel inverter topology with reduction of total standing v...
This paper presents a new multilevel inverter topology with reduced active switches and total standing voltage. The proposed topology can generate a high number of voltage levels in the symmetric configuration. This topology intuitively generates positive and negative cycles without an additional H-bridge unit, which considerably reduces the total standing voltage of the inverter. A cascaded structure is developed from the proposed topology to create higher voltage levels. To show the novelty of the proposed topology, a thorough comparison between the available and the proposed topologies in terms of the number of switches, standing voltages, and dc-sources is presented. Furthermore, the power loss analysis is carried out for various load values. The feasibility of the proposed nine-level inverter is verified with simulation and experimental results.
Power Quality Improvement in Solar Fed Cascaded Multilevel Inverter with Outp...
This document discusses a project to improve power quality in a solar photovoltaic energy conversion system using a cascaded 15-level inverter. Proportional Integral, Artificial Neural Network, and Fuzzy Logic controllers are investigated to eliminate harmonics. Simulations were performed in MATLAB/Simulink and hardware was demonstrated for a 3kWp photovoltaic plant coupled to a multilevel inverter. The fuzzy logic controller provided the best results for voltage regulation and power quality improvement. Experimental results validated the effectiveness of the proposed system for grid interaction while improving power quality.
Residential Community Load Management based on Optimal Design of Standalone H...
This document presents a study on designing a standalone hybrid renewable energy system (HRES) for a residential community in Pakistan using PV, wind, diesel, and battery. Nine system configurations were analyzed using HOMER software to determine the optimal and most economical design. HOMER results showed a PV-wind-battery system with 13.4 kW PV, 4 kW wind, and 20 battery units was optimal, with a net present cost of $28,620 and cost of energy of $0.311/kWh. MATLAB/Simulink modeling validated this design could maintain voltages and safe battery SOC while meeting load, even with generation and demand fluctuations. The HRES design and control strategy presented provides a tool for planning
Reliability evaluation of MPPT based interleaved boost converter for PV system
The demand for power supply and depletion of the conventional energy sources are increasing drastically. So to overcome this problem, the best alternative power generation for conventional fossil fuel is Photovoltaic solar cell based system because of its advantage of pollution free and its availability in abundance with free of cost. In the MPPT based PV system the converters are the most sensitive part. Therefore to provide uninterrupted power supply without compromising the quality of power, reliability evaluation of interleaved boost converter becomes necessary. MATLAB/Simulink is used for the simulation studies and to determine the power losses of various components of the converter which is used in calculating the failure rates and reliability of the interleaved boost converter. Reliability studies of IBC have not been studied much. However there exists few literature in which reliability expression has been developed using Markov technique which is a more complex method as compare to Reliability Block Diagram (RBD). Therefore this paper proposes reliability modeling and reliability evaluation of Interleaved boost converter in MPPT based photo-voltaic system by using simple RBD method.
Power Quality Improvement of Grid-Connected Photovoltaic Systems Using Trans-...
Voltage-source inverter has been used widely in traditional photovoltaic systems which have limitations. To overcome, Z-source inverter has been introduced. In spite of all the features introduced in Z-source inverter, its configuration has been improved over the years, like trans-Z-source inverter which has added advantages compared to traditional inverters, namely buck–boost feature, lesser passive elements, and higher voltage boost gain. In this paper, photovoltaic arrays are connected to the grid via the trans-Z-source inverter with the aim of improving its power quality. Moreover, the shoot through duty ratio is kept constant in the switching control method to add features like lower voltage stress (higher reliability), lower total harmonic distortion (lower maintenance cost), and higher voltage boost ratio. To evaluate the precision of the proposed system, the photovoltaic system is simulated on a standard grid and under partial shading condition which brings about voltage sag, and hence, a dynamic voltage restorer is used to mitigate voltage sag. Simulation results are presented to verify the validation of the proposed photovoltaic system in terms of voltage and current THD reducing 78.2% and 19.7%, respectively.
Power optimisation scheme of induction motor using FLC for electric vehicle
In electric vehicles (EVs) and hybrid EVs, energy efficiency is essential where the energy storage is limited. Adding to its high stability and low cost, the induction motor efficiency improves with loss minimisation. Also, it can consume more power than the actual need to perform its working when it is operating in less than full load condition. This study proposes a control strategy based on the fuzzy logic control (FLC) for EV applications. FLC controller can improve the starting current amplitude and saves more power. Through the MATLAB/SIMULINK software package, the performance of this control was verified through simulation. As compared with the conventional proportional integral derivative controller, the simulation schemes show good, high-performance results in time-domain response and rapid rejection of system-affected disturbance. Therefore, the core losses of the induction motor are greatly reduced, and in this way improves the efficiency of the driving system. Finally, the suggested control system is validated by the experimental results obtained in the authors’ laboratory, which are in good agreement with the simulation results.
Power Flow Control of Interconnected AC-DC Microgrids in Grid-Connected Hybri...
This paper introduces a new approach for power flow control of interconnected AC-DC microgrids in grid-connected hybrid microgrids based on implementing a modified unified interphase power controller (UIPC). A typical grid-connected hybrid microgrid including one AC microgrid and one DC microgrid is considered as studied system. Instead of using the parallel-connected power converters, these microgrids are interconnected using a modified UIPC. As the first contribution of this paper, the conventional structure of UIPC, which uses three power converters in each phase, is modified so that a reduced number of power converters is implemented for power exchange control between AC-DC microgrids. The modified structure includes one power converter in each phase, named as line power converter (LPC), and a power converter which regulates the DC bus voltage, named as bus power converter (BPC) here. The AC microgrid is connected to the main grid through the LPCs which their DC buses are linked and can operate in capacitance mode (CM) or inductance mode (IM). A fuzzy logic controller is used in the control structure of the LPCs. The fuzzy inference system is optimized based on H∞ filtering method to reduce the errors in membership functions design. Through the BPC, the DC voltage of LPCs is supplied by the DC microgrid. However, since the DC microgrid voltage is provided here by a PV system, the DC link voltage of the LPCs is fluctuating. Thus, as the second contribution, to stabilize the DC link fluctuations, a new nonlinear disturbance observer based robust multiple-surface sliding mode control (NDO-MS-SMC) strategy is presented for DC side control of the BPC. The simulation results confirm the effectiveness of the proposed power flow control strategy of the improved UIPC for hybrid microgrids.
Power flow control of hybrid micro grids using modified uipc
Neuro Fuzzy Inference System (ANFIS) controlled modified Unified Inter-Phase Power Controller (UIPC). For study, a classic hybrid micro-grid connected to grid comprising of a AC micro-grid and a DC micro-grid is taken into account. These micro-grids are interconnected employing a modified UIPC, rather than using the power converters connected in parallel. As the first input of this paper is the standard structure of UIPC, which used three power converters in every phase. It was then modified such as number of power converters is used less and implemented for the control of the exchange of power between AC-DC microgrids. In every phase there is one power electronic converter in the improved structure. It is called as Line Power Converter (LPC). Also there is Bus Power Converter (BPC) to regulate the voltage of the DC bus. The Line Power Converters links the AC micro-grid to the main grid. The DC buses are also linked with them. It can be operated in Inductance Mode (IM) as well as Capacitance Mode (CM). The control structure of LPCs has an Adaptive Fuzzy Logic Controller in it. For hybrid micro-grids, the capability of the suggested power flow control strategy is confirmed by the MATLAB simulation results.
Multifunctional grid tied pv system using modified klms control
This paper deals with the modified kernel least mean square (KLMS) control strategy in double-stage, solar photovoltaic (PV) grid tied system to enhance the power quality at common coupling point (CCP). This proposed control algorithm has less oscillations, fast convergence, fast dynamic response and good steady state performance. A control strategy is used to extract the fundamental active current component of load and generates reference grid current for a DC-AC converter. The proposed modified KLMS control mitigates multiple power quality concerns such as harmonics reduction, unity power factor and load balancing. The dynamic performance of proposed system is confirmed into the MATLAB\Simulink environment. Test results on hardware implementation are presented at varying solar irradiation levels and load unbalancing. Test results are found satisfactory and total harmonic distortion (THD) of the grid currents are observed well within the IEEE-519 standard.
Modelling and voltage control of the solar wind hybrid micro-grid with optimi...
Electricity generation from the wind and solar photovoltaic (PV) systems are highly dependent upon weather conditions. Their intermittent nature leads to fluctuations in their output. Therefore, the need for rapid compensation for energy transmission and distribution systems is increasingly important. Static Synchronous Compensator (STATCOM) can be adopted for reactive power compensation and for decreasing the voltage fluctuation caused by the system and renewable energy sources. This study presents modelling of a Solar PV-Wind Hybrid Micro-grid and the increase of the stable operating limit of the system in case of the incorporation of STATCOM is examined. The major contribution of this paper is the optimization of gain parameters of four PI controllers in STATCOM control circuit based on genetic algorithms (GA) and Bacteria Foraging Algorithm (BFA) and therefore obtaining better responses and voltage stability in terms of nonlinear nature of solar-wind hybrid micro-grid. The Simulink models of the system architecture include a wind turbine model, a solar PV power system model and a STATCOM. It is certified that the voltage fluctuation at the end of the bus bar is reduced by 8% using conventional PI controller, by 10% for GA-based PI controller, and by 15% for BFA based PI controller under variable load. The results obtained by GA and BFA-based optimization of PI controllers are compared with that of the conventional controller and better results attained.
Intelligent Power Sharing of DC Isolated Microgrid Based on Fuzzy Sliding Mod...
The document describes a novel droop control strategy for accurate power sharing in an isolated DC microgrid considering uncertainties and disturbances. It proposes using a sliding mode controller based on a Takagi-Sugeno fuzzy model to represent the nonlinear droop characteristics. The control strategy compensates for uncertainties and disturbances to achieve accurate proportional load power sharing without communication. The method is verified through PSIM/Matlab simulation to regulate load changes and ensure system stability in the DC microgrid.
Implementation of solar pv battery and diesel generator based electric vehic...
In this paper, a solar PV (Photovoltaic) array, a battery energy storage (BES), a diesel generator (DG) set and grid based EV charging station (CS) is utilized to provide the incessant charging in islanded, grid connected and DG set connected modes. The charging station is primarily designed to use the solar photovoltaic PV array and a BES to charge the electric vehicle (EV) battery. However, in case of exhausted storage battery and unavailable solar PV array generation, the charging station intelligently takes power from the grid or DG (Diesel Generator) set. However, the power from DG set is drawn in a manner that, it always operates at 80-85% loading to achieve maximum fuel efficiency under all loading conditions. Moreover, in coordination with the storage battery, the charging station regulates the generator voltage and frequency without a mechanical speed governor. It also ensures that the power drawn from the grid or the DG set is at unity power factor (UPF) even at nonlinear loading. Moreover, the PCC (Point of Common Coupling) voltage is synchronized to the grid/ generator voltage to obtain the ceaseless charging. The charging station also performs the vehicle to grid active/reactive power transfer, vehicle to home and vehicle to vehicle power transfer for increasing the operational efficiency of the charging station. The operation of the charging station is experimentally validated using the prototype developed in the laboratory.
High step up quasi-z source dc-dc converter
In this paper, a high step-up Quasi-Z Source (QZS) DC-DC converter is proposed. This converter uses a hybrid switched-capacitors switched-inductor method in order to achieve high voltage gains. The proposed converter have resolved the voltage gain limitation of the basic QZS DC-DC converter while keeping its main advantages such as continuous input current and low voltage stress on capacitors. Compared to the basic converter, the duty cycle is not limited, and the voltage stress on the diodes and switch isn’t increased. In addition to these features, the proposed converter has a flexible structure, and extra stages could be added to it in order to achieve even higher voltage gains without increasing the voltage stress on devices or limiting the duty cycle. The operation principle of the converter and related relationships and waveforms are presented in the paper. Also, a comprehensive comparison between the proposed and other QZS based DC-DC converters is provided which confirms the superiority of the proposed converter. Simulations are done in PSCAD/EMTDC in order to investigate the MPPT capability of the converter. In addition, the valid performance and practicality of the converter are studied through the results obtained from the laboratory built prototype.
Fuel cell integrated unified power quality conditioner for voltage and curren...
This document discusses a proposed Fuel Cell Integrated Unified Power Quality Conditioner (FCI-UPQC) system for improving power quality in a three-phase four-wire distribution grid. The FCI-UPQC uses a four-leg converter on the shunt side and three-leg converter on the series side. An adaptive neuro-fuzzy inference system controller is designed to maintain the DC link voltage. Simulation results in MATLAB/Simulink showed that the FCI-UPQC can effectively compensate for power quality issues like voltage sag, swell, harmonics, and neutral current imbalance. The inclusion of a fuel cell provides real power support during grid interruptions. The paper concludes that the proposed FCI-UPQC
Distributed incremental adaptive filter controlled grid interactive residenti...
This document describes a distributed incremental adaptive filter (DIAF) controlled utility interfaced photovoltaic (PV) - battery microgrid system that is presented with power quality features. The bidirectional controlled converter with a battery mitigates intermittency of a PV array under rapid weather variations. The DIAF control provides harmonics mitigation, load balancing and power factor improvement. It has been demonstrated that the DIAF based control of residential PV/battery microgrid system can continuously supply power by integrating battery backup with a PV array even during outages of the PV array and utility grid. Test results validated the control technique and power quality indices were within IEEE standards.
More from Asoka Technologies (20)
Generation of Higher Number of Voltage Levels by Stacking Inverters of Lower ...
Generation of Higher Number of Voltage Levels by Stacking Inverters of Lower ...
A Variable DC Link based Novel Multilevel Inverter Topology for Low Voltage A...
A Variable DC Link based Novel Multilevel Inverter Topology for Low Voltage A...
A New Family of Step-up Hybrid Switched- Capacitor Integrated Multilevel Inve...
A New Family of Step-up Hybrid Switched- Capacitor Integrated Multilevel Inve...
A multi cell 21-level hybrid multilevel inverter synthesizes a reduced number...
A multi cell 21-level hybrid multilevel inverter synthesizes a reduced number...
A generalized multilevel inverter topology with reduction of total standing v...
A generalized multilevel inverter topology with reduction of total standing v...
Power Quality Improvement in Solar Fed Cascaded Multilevel Inverter with Outp...
Power Quality Improvement in Solar Fed Cascaded Multilevel Inverter with Outp...
Residential Community Load Management based on Optimal Design of Standalone H...
Residential Community Load Management based on Optimal Design of Standalone H...
Reliability evaluation of MPPT based interleaved boost converter for PV system
Reliability evaluation of MPPT based interleaved boost converter for PV system
Power Quality Improvement of Grid-Connected Photovoltaic Systems Using Trans-...
Power Quality Improvement of Grid-Connected Photovoltaic Systems Using Trans-...
Power optimisation scheme of induction motor using FLC for electric vehicle
Power optimisation scheme of induction motor using FLC for electric vehicle
Power Flow Control of Interconnected AC-DC Microgrids in Grid-Connected Hybri...
Power Flow Control of Interconnected AC-DC Microgrids in Grid-Connected Hybri...
Power flow control of hybrid micro grids using modified uipc
Power flow control of hybrid micro grids using modified uipc
Multifunctional grid tied pv system using modified klms control
Multifunctional grid tied pv system using modified klms control
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An f p q droop control in cascaded-type microgrid
- 1. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 An f-P/Q Droop Control in Cascaded-Type Microgrid ABSTRACT: In cascaded-type microgrid, the synchronization and power balance of distributed generators become two new issues that needs to be addressed urgently. To that end, an f-P/Q droop control is proposed in this letter, and its stability is analyzed as well. This proposed droop control is capable to achieve power balance under both resistive-inductive an resistive-capacitive loads autonomously. Compared with the inverse power factor droop control, an obvious advantage consists in extending the scope of application. Finally, the feasibility of the proposed method is verified by simulation results. KEYWORDS: 1. Cascaded-type microgrid 2. Droop control 3. Power balance SOFTWARE: MATLAB/SIMULINK
- 2. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 BLOCK DIAGRAM: Fig. 1. Structure of islanded cascaded-type microgrid. CONTROL SYSTEM: Fig. 2. The local control diagram of the i-th DG.
- 3. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 EXPECTED SIMULATION RESULTS Fig.3. Simulation results of case I. (a) Active power. (b) Reactive power
- 4. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 Fig. 4. Simulation results of case II. (a) Active power. (b) Reactive power.
- 5. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 CONCLUSION: A bridge modular switched-capacitor-based multilevel inverter with optimized UFD-SPWM control method is proposed in the paper. The switched-capacitor-based stage can obtain high conversion efficiency and multiple voltage levels. Meanwhile, it functions as an active energy buffer, enhancing the power decoupling ability and conducing to cut the total size of the twice- line energy buffering capacitance. Furthermore, voltage multi-level in DC-link reduces the switching loss of inversion stage because turn-off voltage stress of switches changes with phase of output voltage rather than always suffers from one relatively high DC voltage. Most importantly, the control method of UFD-SPWM, doubling equivalent witching frequency, is employed in the inversion stage for a high quality output waveform with reduced harmonic. In addition, the optimized voltage level phase maximizes the fundamental component in output voltage pulses to reduce harmonic backflow as possible. Hence, the comprehensive system efficiency has been promoted and up to peak value of 97.6%. Finally, two conversion stages are controlled independently for promoting reliability and decreasing complexity. In future work, detailed loss discussion, including theoretic calculation and validation of loss breakdown, will be presented. REFERENCES: [1] M. Jun, "A new selective loop bias mapping phase disposition PWM with dynamic voltage balance capability for modular multilevel converter," IEEE Trans. Ind. Electron., vol. 61, no. 2, pp. 798-807, Feb. 2014. [2] N. Mehdi, and G. Moschopoulos, "A novel single-stage multilevel type full-bridge converter," IEEE Trans. Ind. Electron., vol. 60, no. 1, pp. 31-42, Jan. 2013.
- 6. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 [3] E. Ehsan and N. B. Mariun, "Experimental results of 47-level switchladder multilevel inverter," IEEE Trans. Ind. Electron., vol. 60, no. 11, pp. 4960-4967, Nov. 2013. [4] J. Lai, “Power conditioning circuit topologies,” IEEE Trans. Ind. Electron., vol. 3, no. 2, pp. 24-34, Jun. 2009. [5] L. He, C. Cheng, “Flying-Capacitor-Clamped Five-Level Inverter Based on Switched- Capacitor Topology,” IEEE Trans. Ind. Electron., vol. 63, no.12, pp. 7814-7822, Sep. 2016.