This document presents a new multilevel DC-link inverter and control algorithm called the "PV permutation algorithm" to overcome the problem of partial shading of photovoltaic (PV) sources connected in series. The algorithm uses direct pulsewidth modulation, sequential permutation of the PV sources, and output generation to control a seven-level inverter and extract maximum power from each PV source under nonuniform irradiance conditions like partial shading. Experimental results demonstrate the application of the new algorithm for real-time maximum power point tracking of each PV source to deliver all available power to the load.
Power Quality Improvement of Grid-Connected Photovoltaic Systems Using Trans-...Asoka Technologies
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 flow control of hybrid micro grids using modified uipcAsoka Technologies
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.
A novel online fuzzy control method of static var compensation for an effecti...Asoka Technologies
The Flexible AC Transmission System (FACTS) technology is a promising technology to achieve complete deregulation of Power System i.e. Generation, Transmission and Distribution as the complete individual units. FACTS is based on power electronic devices, used to enhance the existing transmission capabilities in order to make the transmission system flexible and independent in operation. The loading capability of transmission system can also be enhanced nearer to its thermal limit without affecting the stability. Complete closed-loop smooth control of reactive power can be achieved using shunt connected FACTS devices. Static VAR Compensator (SVC) is one of the shunt connected FACTS devices, which can be utilized for the purpose of reactive power compensation. As the Intelligent FACTS devices make them adaptable, it is emerging as the present state of the art technology. This paper presents the design and simulation of the Fuzzy logic control to vary firing angle of SVC in order to achieve better, smooth and adaptive control of reactive power in transmission systems. The design, modeling and simulations are carried out for the λ/8 Transmission line by placing the compensation at the receiving end (load end) and the results obtained demonstrates the effectiveness of the proposed method.
A simplified phase shift pwm-based feedforward distributed mppt method for gr...Asoka Technologies
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.
Power Quality Improvement of Grid-Connected Photovoltaic Systems Using Trans-...Asoka Technologies
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 flow control of hybrid micro grids using modified uipcAsoka Technologies
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.
A novel online fuzzy control method of static var compensation for an effecti...Asoka Technologies
The Flexible AC Transmission System (FACTS) technology is a promising technology to achieve complete deregulation of Power System i.e. Generation, Transmission and Distribution as the complete individual units. FACTS is based on power electronic devices, used to enhance the existing transmission capabilities in order to make the transmission system flexible and independent in operation. The loading capability of transmission system can also be enhanced nearer to its thermal limit without affecting the stability. Complete closed-loop smooth control of reactive power can be achieved using shunt connected FACTS devices. Static VAR Compensator (SVC) is one of the shunt connected FACTS devices, which can be utilized for the purpose of reactive power compensation. As the Intelligent FACTS devices make them adaptable, it is emerging as the present state of the art technology. This paper presents the design and simulation of the Fuzzy logic control to vary firing angle of SVC in order to achieve better, smooth and adaptive control of reactive power in transmission systems. The design, modeling and simulations are carried out for the λ/8 Transmission line by placing the compensation at the receiving end (load end) and the results obtained demonstrates the effectiveness of the proposed method.
A simplified phase shift pwm-based feedforward distributed mppt method for gr...Asoka Technologies
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.
An integrated boost resonant converter for photovoltaic applicationsAsoka Technologies
Effective photovoltaic power conditioning requires efficient power conversion and accurate maximum power point tracking to counteract the effects of panel mismatch, shading, and general variance in power output during a daily cycle. In this paper, the authors propose an integrated boost resonant converter with low component count, galvanic isolation, simple control, as well as
high efficiency across a wide input and load range. Provided is a discussion of the converter synthesis, key operational features, converter design procedure, and loss analysis, as well as experimental verification by way of a 250-W prototype with a California Energy Commission efficiency of 96.8%.
Design and Simulation of PV Based Two-Phase Interleaved Boost Converter IJMER
In this paper, simulation of PV based two phase interleaved boost converter has been
discussed. Interleaved Boost Converter (IBC) serves several applications which require boost in output
voltage such as fuel cells, photovoltaic cells and batteries etc., because it has several advantages over
conventional DC-DC converters. The configuration of IBC comprises parallel combination of a number
of boost converters with same phase shift and switching frequency. This paper deals with the design of
two-phase IBC for a five level cascaded multilevel inverter (MLI). The source for each bridge of the MLI
has been modelled as PV. The simulation has been carried out using MATLAB/SIMULINK
Fuel cell integrated unified power quality conditioner for voltage and curren...Asoka Technologies
Electrical and electronic devices when exposed to one or more power quality problems are prone to failure. This paper aims to enhance the quality of power in three-phase four-wire distribution grid using Fuel Cell Integrated Unified Power Quality Conditioner (FCI-UPQC). The proposed FCI-UPQC has four-leg converter on the shunt side and three-leg converter on the series side. A combination of a synchronous reference frame (SRF) and Instantaneous Reactive Power (IRP) theories are utilized to generate reference signals of the FCI-UPQC. Also, this paper proposes Adaptive Neuro-Fuzzy Inference System controller to maintain DC link voltage in the FCI-UPQC. The Adaptive Neuro-Fuzzy Inference System controller is designed like a sugeno fuzzy architecture and trained offline using data from the Proportional Integral (PI) controller. The obtained results proved that the proposed FCI-UPQC compensated power quality problems such as voltage sag, swell, harmonics, neutral current, source current imbalance in three-phase four-wire distribution grid. The presence of fuel cell in this work makes more effectiveness of the proposed system by providing real power support during supply interruption on the grid side.
Comparison of Modulation Techniques for Matrix ConverterAsoka Technologies
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.
Real time implementation of a packed u-cell seven-levelAsoka Technologies
In this paper a new cascaded nonlinear controller has been designed and implemented on the packed U-Cell (PUC) seven-level inverter. Proposed controller has been designed based on a simplified model of PUC inverter and consists of a voltage controller as outer loop and a current controller as inner loop. The outer loop regulates the PUC inverter capacitor voltage as the second DC bus. The inner loop is in charge of controlling the flowing current which is also used to charge and discharge that capacitor. The main goal of the whole system is to keep the DC capacitor voltage at a certain level results in generating a smooth and quasi-sine-wave 7-level voltage waveform at the output of the inverter with low switching frequency. The proposed controller performance is verified through experimental tests. Practical results prove the good dynamic performance of the controller in fixing the PUC capacitor voltage for various and variable load conditions and yet generating low harmonic 7-level voltage waveform to deliver power to the loads. Operation as an uninterruptible power supply (UPS) or AC loads interface for photovoltaic energy conversion applications is targeted.
Development of wind and solar based ac microgrid with power quality improveme...Asoka Technologies
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.
Single- and Two-Stage Inverter-Based Grid-Connected Photovoltaic Power Plants...Asoka Technologies
Grid-connected distributed generation sources interfaced with voltage source inverters (VSIs) need to be disconnected from the grid under: 1) excessive dc-link voltage; 2) excessive ac currents; and 3) loss of grid-voltage synchronization. In this paper, the control of single- and two-stage grid-connected VSIs in photovoltaic (PV) power plants is developed to address the issue of inverter disconnecting under various grid faults. Inverter control incorporates reactive power support in the case of voltage sags based on the grid codes’ (GCs) requirements to ride-through the faults and support the grid voltages. A case study of a 1-MW system simulated in MATLAB/Simulink software is used to illustrate the proposed control. Problems that may occur during grid faults along with associated remedies are discussed. The results presented illustrate the capability of the system to ride-through different types of grid faults.
Dynamic modeling of microgrid for grid connected intentional islanding operat...Asoka Technologies
Microgrid is defined as the cluster of multiple distributed generators (DGs) such as renewable energy sources that supply electrical energy. The connection of microgrid is in parallel with the main grid. When microgrid is isolated from remainder of the utility system, it is said to be in intentional islanding mode. In this mode, DG inverter system operates in voltage control mode to provide constant voltage to the local load. During grid connected mode, the Microgrid operates in constant current control mode to supply preset power to the main grid. The main contribution of this paper is summarized as
1) Design of a network based control scheme for inverter based sources, which provides proper current control during grid connected mode and voltage control during islanding mode.
2) Development of an algorithm for intentional islanding detection and synchronization controller required during grid reconnection.
3) Dynamic modeling and simulation are conducted to show system behavior under proposed method using SIMULINK.
From the simulation results using Simulink dynamic models, it can be shown that these controllers provide the microgrid with a deterministic and reliable connection to the grid.
Power Quality Improvement in Solar Fed Cascaded Multilevel Inverter with Outp...Asoka Technologies
The presence of harmonics in solar Photo Voltaic (PV) energy conversion system results in deterioration of power quality. To address such issue, this paper aims to investigate the elimination of harmonics in a solar fed cascaded fifteen level inverter with aid of Proportional Integral (PI), Artificial Neural Network (ANN) and Fuzzy Logic (FL) based controllers. Unlike other techniques, the proposed FLC based approach helps in obtaining reduced harmonic distortions that intend to an enhancement in power quality. In addition to the power quality improvement, this paper also proposed to provide output voltage regulation in terms of maintaining voltage and frequency at the inverter output end in compatible with the grid connection requirements. The simulations are performed in the MATLAB / Simulink environment for solar fed cascaded 15 level inverter incorporating PI, ANN and FL based controllers. To exhibit the proposed technique, a 3 kWp photovoltaic plant coupled to multilevel inverter is designed and hardware is demonstrated. All the three techniques are experimentally investigated with the measurement of power quality metrics along with establishing output voltage regulation.
Statcom for improved dynamic performance of wind farms in power gridAsoka Technologies
Application of FACTS controller called Static Synchronous Compensator STATCOM to improve the performance of power grid with Wind Farms is investigated .The essential feature of the STATCOM is that it has the ability to absorb or inject fastly the reactive power with power grid . Therefore the voltage regulation of the power grid with STATCOM FACTS device is achieved. Moreover restoring the stability of the power system having wind farm after occurring
severe disturbance such as faults or wind farm mechanical power variation is obtained with STATCOM controller . The dynamic model of the power system having wind farm controlled by
proposed STATCOM is developed . To Validate the powerful of the STATCOM FACTS controller , the studied power system is simulated and subjected to different severe disturbances . The results prove the effectiveness of the proposed STATCOM controller in terms of fast damping the power system oscillations and restoring the power system stability .
An integrated boost resonant converter for photovoltaic applicationsAsoka Technologies
Effective photovoltaic power conditioning requires efficient power conversion and accurate maximum power point tracking to counteract the effects of panel mismatch, shading, and general variance in power output during a daily cycle. In this paper, the authors propose an integrated boost resonant converter with low component count, galvanic isolation, simple control, as well as
high efficiency across a wide input and load range. Provided is a discussion of the converter synthesis, key operational features, converter design procedure, and loss analysis, as well as experimental verification by way of a 250-W prototype with a California Energy Commission efficiency of 96.8%.
Design and Simulation of PV Based Two-Phase Interleaved Boost Converter IJMER
In this paper, simulation of PV based two phase interleaved boost converter has been
discussed. Interleaved Boost Converter (IBC) serves several applications which require boost in output
voltage such as fuel cells, photovoltaic cells and batteries etc., because it has several advantages over
conventional DC-DC converters. The configuration of IBC comprises parallel combination of a number
of boost converters with same phase shift and switching frequency. This paper deals with the design of
two-phase IBC for a five level cascaded multilevel inverter (MLI). The source for each bridge of the MLI
has been modelled as PV. The simulation has been carried out using MATLAB/SIMULINK
Fuel cell integrated unified power quality conditioner for voltage and curren...Asoka Technologies
Electrical and electronic devices when exposed to one or more power quality problems are prone to failure. This paper aims to enhance the quality of power in three-phase four-wire distribution grid using Fuel Cell Integrated Unified Power Quality Conditioner (FCI-UPQC). The proposed FCI-UPQC has four-leg converter on the shunt side and three-leg converter on the series side. A combination of a synchronous reference frame (SRF) and Instantaneous Reactive Power (IRP) theories are utilized to generate reference signals of the FCI-UPQC. Also, this paper proposes Adaptive Neuro-Fuzzy Inference System controller to maintain DC link voltage in the FCI-UPQC. The Adaptive Neuro-Fuzzy Inference System controller is designed like a sugeno fuzzy architecture and trained offline using data from the Proportional Integral (PI) controller. The obtained results proved that the proposed FCI-UPQC compensated power quality problems such as voltage sag, swell, harmonics, neutral current, source current imbalance in three-phase four-wire distribution grid. The presence of fuel cell in this work makes more effectiveness of the proposed system by providing real power support during supply interruption on the grid side.
Comparison of Modulation Techniques for Matrix ConverterAsoka Technologies
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.
Real time implementation of a packed u-cell seven-levelAsoka Technologies
In this paper a new cascaded nonlinear controller has been designed and implemented on the packed U-Cell (PUC) seven-level inverter. Proposed controller has been designed based on a simplified model of PUC inverter and consists of a voltage controller as outer loop and a current controller as inner loop. The outer loop regulates the PUC inverter capacitor voltage as the second DC bus. The inner loop is in charge of controlling the flowing current which is also used to charge and discharge that capacitor. The main goal of the whole system is to keep the DC capacitor voltage at a certain level results in generating a smooth and quasi-sine-wave 7-level voltage waveform at the output of the inverter with low switching frequency. The proposed controller performance is verified through experimental tests. Practical results prove the good dynamic performance of the controller in fixing the PUC capacitor voltage for various and variable load conditions and yet generating low harmonic 7-level voltage waveform to deliver power to the loads. Operation as an uninterruptible power supply (UPS) or AC loads interface for photovoltaic energy conversion applications is targeted.
Development of wind and solar based ac microgrid with power quality improveme...Asoka Technologies
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.
Single- and Two-Stage Inverter-Based Grid-Connected Photovoltaic Power Plants...Asoka Technologies
Grid-connected distributed generation sources interfaced with voltage source inverters (VSIs) need to be disconnected from the grid under: 1) excessive dc-link voltage; 2) excessive ac currents; and 3) loss of grid-voltage synchronization. In this paper, the control of single- and two-stage grid-connected VSIs in photovoltaic (PV) power plants is developed to address the issue of inverter disconnecting under various grid faults. Inverter control incorporates reactive power support in the case of voltage sags based on the grid codes’ (GCs) requirements to ride-through the faults and support the grid voltages. A case study of a 1-MW system simulated in MATLAB/Simulink software is used to illustrate the proposed control. Problems that may occur during grid faults along with associated remedies are discussed. The results presented illustrate the capability of the system to ride-through different types of grid faults.
Dynamic modeling of microgrid for grid connected intentional islanding operat...Asoka Technologies
Microgrid is defined as the cluster of multiple distributed generators (DGs) such as renewable energy sources that supply electrical energy. The connection of microgrid is in parallel with the main grid. When microgrid is isolated from remainder of the utility system, it is said to be in intentional islanding mode. In this mode, DG inverter system operates in voltage control mode to provide constant voltage to the local load. During grid connected mode, the Microgrid operates in constant current control mode to supply preset power to the main grid. The main contribution of this paper is summarized as
1) Design of a network based control scheme for inverter based sources, which provides proper current control during grid connected mode and voltage control during islanding mode.
2) Development of an algorithm for intentional islanding detection and synchronization controller required during grid reconnection.
3) Dynamic modeling and simulation are conducted to show system behavior under proposed method using SIMULINK.
From the simulation results using Simulink dynamic models, it can be shown that these controllers provide the microgrid with a deterministic and reliable connection to the grid.
Power Quality Improvement in Solar Fed Cascaded Multilevel Inverter with Outp...Asoka Technologies
The presence of harmonics in solar Photo Voltaic (PV) energy conversion system results in deterioration of power quality. To address such issue, this paper aims to investigate the elimination of harmonics in a solar fed cascaded fifteen level inverter with aid of Proportional Integral (PI), Artificial Neural Network (ANN) and Fuzzy Logic (FL) based controllers. Unlike other techniques, the proposed FLC based approach helps in obtaining reduced harmonic distortions that intend to an enhancement in power quality. In addition to the power quality improvement, this paper also proposed to provide output voltage regulation in terms of maintaining voltage and frequency at the inverter output end in compatible with the grid connection requirements. The simulations are performed in the MATLAB / Simulink environment for solar fed cascaded 15 level inverter incorporating PI, ANN and FL based controllers. To exhibit the proposed technique, a 3 kWp photovoltaic plant coupled to multilevel inverter is designed and hardware is demonstrated. All the three techniques are experimentally investigated with the measurement of power quality metrics along with establishing output voltage regulation.
Statcom for improved dynamic performance of wind farms in power gridAsoka Technologies
Application of FACTS controller called Static Synchronous Compensator STATCOM to improve the performance of power grid with Wind Farms is investigated .The essential feature of the STATCOM is that it has the ability to absorb or inject fastly the reactive power with power grid . Therefore the voltage regulation of the power grid with STATCOM FACTS device is achieved. Moreover restoring the stability of the power system having wind farm after occurring
severe disturbance such as faults or wind farm mechanical power variation is obtained with STATCOM controller . The dynamic model of the power system having wind farm controlled by
proposed STATCOM is developed . To Validate the powerful of the STATCOM FACTS controller , the studied power system is simulated and subjected to different severe disturbances . The results prove the effectiveness of the proposed STATCOM controller in terms of fast damping the power system oscillations and restoring the power system stability .
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Εργασία της μαθήτριας Αγγελικής Χαριστέ στα πλάισια του Πολιτιστικού Προγράμματος «Μαθαίνω μια γλώσσα, ανακαλύπτω έναν πολιτισμό. Προσωπικότητες από το γερμανόφωνο χώρο του αθλητισμού και της μόδας». 2ο Γυμνάσιο Ευόσμου, 2014-15.
A Survey on the Performance of the Various MPPT Techniques of Standalone PV G...IJSRD
Maximum Power Point Tracking (MPPT) controller is very important part of the solar generation system. This paper presents the basic need and the various methods and techniques of maximum power tracking (MPPT) control. Every technique of MPPT control is evaluated based on its ability to detect multiple maxima, efficiency of the output solar power, cost and way of implementation, rate of convergence etc. the Perturbation and Observation technique and Incremental conductance Technique are widely used in MPPT control due to their advantages.
Control of Two Stage PV Power System under the Unbalanced Three Phase Grid Vo...ijtsrd
This paper proposes a dynamic power decoupling DPD strategy for the three phase grid tied PV power system without increasing the dc link capacitance. Under normal condition, the interleaved boost converter will extract the maximum power point MPP from the PV array and the three phase inverter will inject the power to the grid. During the unbalanced grid fault scenario, the input power and current of the interleaved boost converter will be controlled by the proposed DPD to achieve the power decoupling capability as well as to eliminate the dc link voltage oscillation. The proposed work has been carried out in MATLAB, and the results are presented. Manasa | Nirmaladevi ""Control of Two Stage PV Power System under the Unbalanced Three-Phase Grid Voltages"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-2 , February 2020,
URL: https://www.ijtsrd.com/papers/ijtsrd30091.pdf
Paper Url : https://www.ijtsrd.com/engineering/electrical-engineering/30091/control-of-two-stage-pv-power-system-under-the-unbalanced-three-phase-grid-voltages/manasa
Design and Analysis of Three Phase Inverter with Two Buck/Boost MPPTs for DC ...IJERA Editor
Anintegration and operation of a three-phase inverter with twobuck/boost maximum power point trackers
(MPPTs) for dc-distribution applications. In a dc-distribution system, a three phase inverter isrequired to control
the power flow between dc busand three phase ac grid, and to regulate the dc bus to a certainrange of voltages.
A droop regulation mechanism according to the inverter inductor current levels to reduce capacitor size, balance
power flow, and accommodate load variation is proposed. Since thephotovoltaic (PV) array voltage can vary
from 0 to 5000 V, especially with thin-film PV panels, the MPPT topology is formed with buck and boost
converters to operate at the dc-bus voltage around 4000 V, reducing the voltage stress of its followed inverter.
Additionally, the controller can online check the input configuration of the two MPPTs, equally distribute the
PV-array output current to the two MPPTs in parallel operation, and switch control laws to smooth out mode
transition. A comparison between the conventional boost MPPT and the proposed buck/boost MPPT integrated
with a PV inverter is also presented. Asingle-phase bidirectional inverter with two buck/boost maximum power
point trackers (MPPTs) by using the closed loop circuit. This project is workout bySimulink using mat lab.
Modeling and simulation of three phases cascaded H-bridge grid-tied PV inverterjournalBEEI
In this paper a control scheme for three phase seven level cascaded H-bridge inverter for grid tied PV system is presented. As power generation from PV depends on varing environmental conditions, for extractraction of maximum power from PV array, fuzzy MPPT controller is incorporated with each PV array. It gives fast and accurate response. To maintain the grid current
sinusoidal under varying conditions, a digital PI controller scheme is adopted. A MATLAB/Simulink model is developed for this purpose and results are presented. At last THD analysis is carried out in order to validate the performance of the overall system. As discussed, with this control strategy the balanced grid current is obtained keeping THD values with in the specified range of IEEE-519 standard.
Modeling and simulation of three phases cascaded H-bridge grid-tied PV inverterjournalBEEI
In this paper a control scheme for three phase seven level cascaded H-bridge inverter for grid tied PV system is presented. As power generation from PV depends on varing environmental conditions, for extractraction of maximum power from PV array, fuzzy MPPT controller is incorporated with each PV array. It gives fast and accurate response. To maintain the grid current sinusoidal under varying conditions, a digital PI controller scheme is adopted. A MATLAB/Simulink model is developed for this purpose and results are presented. At last THD analysis is carried out in order to validate the performance of the overall system. As discussed, with this control strategy the balanced grid current is obtained keeping THD values with in the specified range of IEEE-519 standard.
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Integrated energy management converter based on maximum power point tracking...IJECEIAES
This paper presents an integrated power control system for photovoltaic systems based on maximum power point tracking (MPPT). The architecture presented in this paper is designed to extract more power from photovoltaic panels under different partial obscuring conditions. To control the MPPT block, the integrated system used the ripple correlation control algorithm (RCC), as well as a high-efficiency synchronous direct current (DC-DC) boost power converter. Using 180 nm complementary metal-oxidesemiconductor (CMOS) technology, the proposed MPPT was designed, simulated, and layout in virtuoso cadence. The system is attached to a twocell in series that generates a 5.2 V average output voltage, 656.6 mA average output current, and power efficiency of 95%. The final design occupies only 1.68 mm2 .
Maximum power point tracking of pv arrays under partial shading condition usi...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Multilevel dc link inverter and control algorithm to overcome the pv partial shading
1. MULTILEVEL DC-LINK INVERTER AND CONTROL ALGORITHM
TO OVERCOME THE PV PARTIAL SHADING
ABSTRACT:
This letter presents for the first time the application of multilevel dc-link inverter to overcome the
problem of partial shading of individual photovoltaic (PV) sources which are connected in series. The “PV
permutation algorithm,” as a new method, is developed for the control of the inverter so as to extract the
maximum power form each PV source under partial shading and to deliver all that power to the load. The
algorithm is based on combination of the direct pulsewidth modulation, the sequential permutation PV
sources, and the output generation to control the multilevel dc-link inverter. The algorithm is applied
successfully to a seven-level inverter with separate maximum power point tracking algorithm for each PV
source and under nonuniform irradiance (partial shading). Digital processing unit F28335 eZdsp is used to
control the PV system in the real-time mode, and MATLAB-Simulink real-time data exchange is employed
to display the extracted power and to control the system parameters via a designed graphical user interface
window. The implementation and experimental results are presented.