This paper presents a grid interfacing inverter which compensates power quality problems and also interface Renewable Energy Sources with the help of electric grid. Renewable Energy Sources are being increasingly connected in distribution system utilizing power electronic converters. Grid interfacing inverter can be used: 1) To improve the transfer of active power harvested from RES; 2) To meet load reactive power demand support ; 3) To reduce current harmonics by incorporating the current harmonic compensator at point of common coupling(PCC) ; 4) current unbalance and neutral current compensation in case of 3-phase 4-wire system. The fuzzy logic can be used in many applications especially, when the process/models are complex to analyse by using classical methods. Mainly fuzzy logic controller is used to control DC capacitor voltage. Simulations are carried out using MATLAB/SIMULINK to verify the performance of the controller. The output shows the controller has fast dynamic response high accuracy of tracking DC voltage reference and robust to load parameters variations.
Grid Interconnection of Renewable Energy Sources at the Distribution Level Wi...Pradeep Avanigadda
Renewable energy resources (RES) are being increasingly connected in distribution systems utilizing power electronic converters.
This project presents a novel control strategy for achieving maximum benefits from these grid-interfacing inverters when installed in 3-phase 4-wire distribution systems.
The inverter can thus be utilized as:
1) power converter to inject power generated from RES to the grid &
2) shunt APF to compensate current unbalance, load current harmonics, load reactive power demand and load neutral current.
A CONTROL APPROACH FOR GRID INTERFACING INVERTER IN 3 PHASE 4 WIRE DISTRIBUT...IJMER
With the increase in load demand, the Renewable Energy Sources (RES) are
increasingly connected in the distribution systems which utilizes power electronic
Converters/Inverters. Nowadays, 3-phase 4-wire distribution power system has been widely used in
residential and office buildings, manufacturing facilities, schools etc This paper presents a novel
control strategy for achieving maximum benefits from the grid-interfacing inverters when installed in
3-phase 4-wire distribution systems. The inverter can thus be utilized as: 1) power converter to inject
power to the grid, and 2) shunt APF to compensate current unbalance, load current harmonics and
load neutral current. All of these functions may be accomplished either individually or
simultaneously. This new control concept is demonstrated with extensive MATLAB/Simulink
simulation studies
Power-Quality Improvement Features In Grid Interconnection of Wind Energy Sou...AM Publications
The increased power demand, the depletion of the fossil fuel resources and the growth of the environmental pollution has led
the world to think seriously of other alternative sources of energy. So renewable energy resources (RES) are being connected to the
distribution systems, mostly done by using power electronic converters. A new control strategy for achieving maximum advantage from
these grid-interfacing inverters which are when installed in 3-phase 4-wire distribution systems is given in this paper. With the inverter
control, the inverter can be used as a multi-function device, which includes the function of: 1) power converter to inject power generated
from RES to the grid, and 2) shunt APF to compensate current unbalance, load current harmonics, load reactive power demand and
load neutral current. These functions of the inverter can be done either individually or simultaneously. The proposed inverter with the
control when connected, helps the 3-phase 4-wire linear/non-linear unbalanced load at point of common coupling appear as balanced
linear load to the grid. With MATLAB/Simulink simulation studies, the proposed control technique is demonstrated and evaluated here.
Analysis of power quality improvement in grid connected wind driven induction...eSAT Journals
Abstract As a promising renewable alternative, the wind power is one of the significant sources of generation. Reactive power compensation and harmonic reduction in a low voltage distribution networks for integration of wind power to the grid are the main issues addressed in this paper. This paper proposes a control scheme based on instaneous Pq theory for compensating the reactive power requirement of a three phase grid connected wind driven induction generator as well as the harmonics produced by the non linear load connected to the PCC using STATCOM. The proposed control scheme is simulated using MATLAB/SIMULINK. The Simulation results are presented in this paper. Keywords- wind power, distribution network, induction generator, STATCOM, reactive power.
Improved Power Quality by using STATCOM Under Various Loading ConditionsIJMTST Journal
A Power quality problem is an occurrence manifested as a nonstandard voltage, current or frequency that
results in a failure or a mis-operation of end user equipment’s. Utility distribution networks, sensitive
industrial loads and critical commercial operations suffer from various types of outages and service
interruptions which can cost significant financial losses. With the restructuring of power systems and with
shifting trend towards distributed and dispersed generation, the issue of power quality is going to take
newer dimensions. Injection of the wind power into an electric grid affects the power quality. The
performance of the wind turbine and thereby power quality are determined on the basis of measurements
and the norms followed according to the guideline specified in International Electro-technical Commission
standard, IEC-61400. The influence of the wind turbine in the grid system concerning the power quality
measurements are-the active power, reactive power, variation of voltage, flicker, harmonics, and electrical
behavior of switching operation and these are measured according to national/international guidelines.
Static Compensator (STATCOM) is connected at a point of common coupling with a battery energy storage
system (BESS) to mitigate the power quality issues. The battery energy storage is integrated to sustain the
real power source under fluctuating wind power. Here two control schemes for STATCOM are Fuzzy logic
controller and hybrid Fuzzy logic controller. We can better response for hybrid fuzzy compare to fuzzy logic
controller. The STATCOM control scheme for the grid connected wind energy generation system for power
quality improvement is simulated using MATLAB/SIMULINK in power system block set. Finally the proposed
scheme is applied for both balanced and unbalanced linear nonlinear loads.
Grid Interconnection of Renewable Energy Sources at the Distribution Level Wi...Pradeep Avanigadda
Renewable energy resources (RES) are being increasingly connected in distribution systems utilizing power electronic converters.
This project presents a novel control strategy for achieving maximum benefits from these grid-interfacing inverters when installed in 3-phase 4-wire distribution systems.
The inverter can thus be utilized as:
1) power converter to inject power generated from RES to the grid &
2) shunt APF to compensate current unbalance, load current harmonics, load reactive power demand and load neutral current.
A CONTROL APPROACH FOR GRID INTERFACING INVERTER IN 3 PHASE 4 WIRE DISTRIBUT...IJMER
With the increase in load demand, the Renewable Energy Sources (RES) are
increasingly connected in the distribution systems which utilizes power electronic
Converters/Inverters. Nowadays, 3-phase 4-wire distribution power system has been widely used in
residential and office buildings, manufacturing facilities, schools etc This paper presents a novel
control strategy for achieving maximum benefits from the grid-interfacing inverters when installed in
3-phase 4-wire distribution systems. The inverter can thus be utilized as: 1) power converter to inject
power to the grid, and 2) shunt APF to compensate current unbalance, load current harmonics and
load neutral current. All of these functions may be accomplished either individually or
simultaneously. This new control concept is demonstrated with extensive MATLAB/Simulink
simulation studies
Power-Quality Improvement Features In Grid Interconnection of Wind Energy Sou...AM Publications
The increased power demand, the depletion of the fossil fuel resources and the growth of the environmental pollution has led
the world to think seriously of other alternative sources of energy. So renewable energy resources (RES) are being connected to the
distribution systems, mostly done by using power electronic converters. A new control strategy for achieving maximum advantage from
these grid-interfacing inverters which are when installed in 3-phase 4-wire distribution systems is given in this paper. With the inverter
control, the inverter can be used as a multi-function device, which includes the function of: 1) power converter to inject power generated
from RES to the grid, and 2) shunt APF to compensate current unbalance, load current harmonics, load reactive power demand and
load neutral current. These functions of the inverter can be done either individually or simultaneously. The proposed inverter with the
control when connected, helps the 3-phase 4-wire linear/non-linear unbalanced load at point of common coupling appear as balanced
linear load to the grid. With MATLAB/Simulink simulation studies, the proposed control technique is demonstrated and evaluated here.
Analysis of power quality improvement in grid connected wind driven induction...eSAT Journals
Abstract As a promising renewable alternative, the wind power is one of the significant sources of generation. Reactive power compensation and harmonic reduction in a low voltage distribution networks for integration of wind power to the grid are the main issues addressed in this paper. This paper proposes a control scheme based on instaneous Pq theory for compensating the reactive power requirement of a three phase grid connected wind driven induction generator as well as the harmonics produced by the non linear load connected to the PCC using STATCOM. The proposed control scheme is simulated using MATLAB/SIMULINK. The Simulation results are presented in this paper. Keywords- wind power, distribution network, induction generator, STATCOM, reactive power.
Improved Power Quality by using STATCOM Under Various Loading ConditionsIJMTST Journal
A Power quality problem is an occurrence manifested as a nonstandard voltage, current or frequency that
results in a failure or a mis-operation of end user equipment’s. Utility distribution networks, sensitive
industrial loads and critical commercial operations suffer from various types of outages and service
interruptions which can cost significant financial losses. With the restructuring of power systems and with
shifting trend towards distributed and dispersed generation, the issue of power quality is going to take
newer dimensions. Injection of the wind power into an electric grid affects the power quality. The
performance of the wind turbine and thereby power quality are determined on the basis of measurements
and the norms followed according to the guideline specified in International Electro-technical Commission
standard, IEC-61400. The influence of the wind turbine in the grid system concerning the power quality
measurements are-the active power, reactive power, variation of voltage, flicker, harmonics, and electrical
behavior of switching operation and these are measured according to national/international guidelines.
Static Compensator (STATCOM) is connected at a point of common coupling with a battery energy storage
system (BESS) to mitigate the power quality issues. The battery energy storage is integrated to sustain the
real power source under fluctuating wind power. Here two control schemes for STATCOM are Fuzzy logic
controller and hybrid Fuzzy logic controller. We can better response for hybrid fuzzy compare to fuzzy logic
controller. The STATCOM control scheme for the grid connected wind energy generation system for power
quality improvement is simulated using MATLAB/SIMULINK in power system block set. Finally the proposed
scheme is applied for both balanced and unbalanced linear nonlinear loads.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Power Quality Improvement by UPQC based on Voltage Source ConvertersIJRST Journal
In modern power system consists of wide range of electrical, electronic and power electronic equipment in commercial and industrial applications. Since most of the electronic equipment’s are nonlinear in nature these will induce harmonics in the system, which affect the sensitive loads to be fed from the system. These problems are partially solved with the help of LC passive filters. However, this kind of filter cannot solve random variation in the load current wave form and voltage wave form. Active filters can resolve this problem. However, the cost of active filters is high. They are difficult to implement in large scale. Additionally, they also present lower efficiency than shunt passive filters. One of the many solutions is the use of a combined system of shunt and active series filters like Unified Power Quality Conditioner (UPQC) which aims at achieving a low cost under highly effective control. The UPQC device combines a shunt active filter together with a series active filter in a back-to-back configuration, to simultaneously compensate the supply voltage and the load current or to mitigate any type of voltage and current fluctuations and power factor correction in a power distribution network, such that improved power quality can be made available at the point of common coupling. The control strategies are modeled using MATLAB/SIMULINK. The performance is also observed under influence of utility side disturbances such as harmonics and voltage sags. The simulation results are compared without and with UPQC for the verification of results.
Enhancement in Power Quality With Grid Interconnection of Renewable Energy So...IJERA Editor
At present the Renewable energy resources (RES) are being increasingly connected in distribution systems utilizing power electronic converters. This paper presents a novel control strategy for achieving maximum benefits from these grid-interfacing inverters when installed in 3-phase 4-wire distribution systems. The inverter is controlled to perform as a multi-function device by incorporating active power filter functionality. The inverter can thus be utilized as power converter to inject power generated from RES to the grid and shunt APF to compensate current unbalance, load current harmonics, load reactive power demand and load neutral current. All of these functions may be accomplished either individually or simultaneously. With such a control, the combination of grid-interfacing inverter and the 3-phase 4-wire linear/non-linear unbalanced load at point of common coupling appears as balanced linear load to the grid. This new control concept is demonstrated with extensive MATLAB/Simulink simulation studies and validated through digital signal processor-based laboratory experimental results.
NEW STATCOM CONTROL SCHEME FOR POWER QUALITY IMPROVEMENT IN WIND FARM.sannuthi yaramapu
Now a days we are facing so many problems with power quality issues. So in order to mitigate these problems and to improve the power quality we are using new STATCOM control scheme in wind farm.
Injection of the wind power into an electric grid affects the power quality. The performance of the wind turbine and thereby power quality are determined on the basis of measurements and the norms followed according to the guideline specified in International Electro-technical Commission standard, IEC-61400. The influence of the wind turbine in the grid system concerning the power quality measurements are-the active power, reactive power, variation of voltage, flicker, harmonics, and electrical behavior of switching operation and these are measured according to national/international guidelines. The paper study demonstrates the power quality problem due to installation of wind turbine with the grid. In this proposed scheme STATic COMpensator (STATCOM) is connected at a point of common coupling with a battery energy storage system (BESS) to mitigate the power quality issues. The battery energy storage is integrated to sustain the real power source under fluctuating wind power. The STATCOM control scheme for the grid connected wind energy generation system for power quality improvement is simulated using MATLAB/SIMULINK in power system block set. The effectiveness of the proposed scheme relives the main supply source from the reactive power demand of the load and the induction generator. The development of the grid co-ordination rule and the scheme for improvement in power quality norms as per IEC-standard on the grid has been presented.
Power Quality Improvement in Grid Connected PV Systemijtsrd
The general trends in the past decade of increasing solar cell efficiency, decreasing PV system costs, increasing government incentive programs, and several other factors have all combined synergistically to reduce the barriers of entry for PV systems to enter the market and expand their contribution to the global energy portfolio. The shortcomings of current inverter functions which link PV systems to the utility network are becoming transparent as PV penetration levels continue to increase. In this paper an analysis of solar system connected with the grid has been done. The system is subjected with two types of perturbations, i.e. variable load and the variable irradiance level which changes the output of the solar system. The design, modeling, and analysis of a grid-tied PV system are performed in the MATLAB software simulation environment. Solar cell works on the principle of photo voltaic effect, which has nonlinear voltage and current characteristics. These characteristics are improved with the help of maximum power point tracking (MPPT) controller. MPPT controller helps to feed the inverter with maximum power from the solar system. Results indicate that in the presence of grid disturbances the inverter can react dynamically to help restore the power system back to its normal state. A harmonic analysis was also performed indicating the inverter under study met the applicable power quality standards for distributed energy resources Anjali | Gourav Sharma"Power Quality Improvement in Grid Connected PV System" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-1 | Issue-4 , June 2017, URL: http://www.ijtsrd.com/papers/ijtsrd2196.pdf http://www.ijtsrd.com/engineering/electrical-engineering/2196/power-quality-improvement-in-grid-connected-pv-system/anjali
statcom-grid connected wind energy generating system for power qualityy impro...Venu Gopal
—Injection of the wind power into an electric grid affects the power quality. The performance of the wind turbine and thereby power quality are determined on the basis of measurements and the norms followed according to the guideline specified in International Electro-technical Commission standard, IEC-61400. The influence of the wind turbine in the grid system concerning the power quality measurements are-the active power, reactive power, variation of voltage, flicker, harmonics, and electrical behavior of switching operation and these are measured according to national/international guidelines. The paper study demonstrates the power quality problem due to installation of wind turbinewith the grid. In thisproposed scheme STATic COMpensator (STATCOM) is connected at a point of common coupling with a battery energy storage system (BESS) to mitigate the power quality issues. The battery energy storage is integrated to sustain the real power source under fluctuating wind power. The STATCOM control scheme for the grid connected wind energy generation system for power quality improvement is simulated using MATLAB/SIMULINK in power system block set. The effectiveness of the proposed scheme relives the main supply source from the reactivepower demand of the load and the induction generator. The development of the grid co-ordination rule and the scheme for improvement in power quality norms as per IEC-standard on the grid has been presented
A brief and basic presentation of interconnections of pwer system,it covers all the basic aspects of power system interconnection that how systems can be built with interconnections
Improvement of power quality has to be treated as a matter of at most importance in the open
market economy due to the increased use of non linear loads. Several devices have been used to mitigate
the power quality problems. Now a days researchers are concentrating on the use of FACT devices to
overcome power quality issues. Unified Power Quality Conditioner is one among such FACT devices upon
which this paper has concentrated for mitigating the Power Quality problems. Here a 3 phase 3 wire
UPQC is realised using MATLAB/SIMULINK to mitigate voltage sag and swell as well as to maintain
sinusoidal voltage and current at PCC irrespective of load dynamics.
Simulation and Analysis of a D-STATCOM for Load Compensation and Power Facto...IJMER
Power Generation and Transmission is a complex process, requiring the working of many
components of the power system in tandem to maximize the output. One of the main components to form
a major part is the reactive power in the system. It is required to maintain the voltage to deliver the
active power through the lines. Loads like motor loads and other loads require reactive power for their
operation. To improve the performance of ac power systems, we need to manage this reactive power in
an efficient way and this is known as reactive power compensation. In developing countries like India,
where the variation of power frequency and many such other determinants of power quality are
themselves a serious question, it is very vital to take positive steps in this direction.
The work presented here illustrates a method to compensate for the load reactive power using a
DSTATCOM
A DSTATCOM injects a current into the system to provide for the reactive component of the load
current. The validity of proposed method and achievement of desired compensation are confirmed by
the results of the simulation in MATLAB/ Simulink.
A Novel Technique for Enhancing Active and Reactive Power Quality for Renewab...IJMER
Renewable energy resources (RES) are being increasingly connected in distribution systems utilizing power electronic converters. This paper presents a novel control strategy for achieving maximum benefits from these grid-interfacing inverters when installed in 3-phase 4-wire distribution systems. The inverter is controlled to perform as a multi-function device by incorporating active power filter functionality. The inverter can thus be utilized as: 1) power converter to inject power generated from RES to the grid, and 2) shunt APF to compensate current unbalance, load current harmonics, load reactive power demand and load neutral current. All of these functions may be accomplished either individually or simultaneously. With such a control, the combination of grid-interfacing inverter and the 3-phase 4-wire linear/non-linear unbalanced load at point of common coupling appears as balanced linear load to the grid. This new control concept is demonstrated with extensive MATLAB/Simulink simulation studies and results.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Power Quality Improvement by UPQC based on Voltage Source ConvertersIJRST Journal
In modern power system consists of wide range of electrical, electronic and power electronic equipment in commercial and industrial applications. Since most of the electronic equipment’s are nonlinear in nature these will induce harmonics in the system, which affect the sensitive loads to be fed from the system. These problems are partially solved with the help of LC passive filters. However, this kind of filter cannot solve random variation in the load current wave form and voltage wave form. Active filters can resolve this problem. However, the cost of active filters is high. They are difficult to implement in large scale. Additionally, they also present lower efficiency than shunt passive filters. One of the many solutions is the use of a combined system of shunt and active series filters like Unified Power Quality Conditioner (UPQC) which aims at achieving a low cost under highly effective control. The UPQC device combines a shunt active filter together with a series active filter in a back-to-back configuration, to simultaneously compensate the supply voltage and the load current or to mitigate any type of voltage and current fluctuations and power factor correction in a power distribution network, such that improved power quality can be made available at the point of common coupling. The control strategies are modeled using MATLAB/SIMULINK. The performance is also observed under influence of utility side disturbances such as harmonics and voltage sags. The simulation results are compared without and with UPQC for the verification of results.
Enhancement in Power Quality With Grid Interconnection of Renewable Energy So...IJERA Editor
At present the Renewable energy resources (RES) are being increasingly connected in distribution systems utilizing power electronic converters. This paper presents a novel control strategy for achieving maximum benefits from these grid-interfacing inverters when installed in 3-phase 4-wire distribution systems. The inverter is controlled to perform as a multi-function device by incorporating active power filter functionality. The inverter can thus be utilized as power converter to inject power generated from RES to the grid and shunt APF to compensate current unbalance, load current harmonics, load reactive power demand and load neutral current. All of these functions may be accomplished either individually or simultaneously. With such a control, the combination of grid-interfacing inverter and the 3-phase 4-wire linear/non-linear unbalanced load at point of common coupling appears as balanced linear load to the grid. This new control concept is demonstrated with extensive MATLAB/Simulink simulation studies and validated through digital signal processor-based laboratory experimental results.
NEW STATCOM CONTROL SCHEME FOR POWER QUALITY IMPROVEMENT IN WIND FARM.sannuthi yaramapu
Now a days we are facing so many problems with power quality issues. So in order to mitigate these problems and to improve the power quality we are using new STATCOM control scheme in wind farm.
Injection of the wind power into an electric grid affects the power quality. The performance of the wind turbine and thereby power quality are determined on the basis of measurements and the norms followed according to the guideline specified in International Electro-technical Commission standard, IEC-61400. The influence of the wind turbine in the grid system concerning the power quality measurements are-the active power, reactive power, variation of voltage, flicker, harmonics, and electrical behavior of switching operation and these are measured according to national/international guidelines. The paper study demonstrates the power quality problem due to installation of wind turbine with the grid. In this proposed scheme STATic COMpensator (STATCOM) is connected at a point of common coupling with a battery energy storage system (BESS) to mitigate the power quality issues. The battery energy storage is integrated to sustain the real power source under fluctuating wind power. The STATCOM control scheme for the grid connected wind energy generation system for power quality improvement is simulated using MATLAB/SIMULINK in power system block set. The effectiveness of the proposed scheme relives the main supply source from the reactive power demand of the load and the induction generator. The development of the grid co-ordination rule and the scheme for improvement in power quality norms as per IEC-standard on the grid has been presented.
Power Quality Improvement in Grid Connected PV Systemijtsrd
The general trends in the past decade of increasing solar cell efficiency, decreasing PV system costs, increasing government incentive programs, and several other factors have all combined synergistically to reduce the barriers of entry for PV systems to enter the market and expand their contribution to the global energy portfolio. The shortcomings of current inverter functions which link PV systems to the utility network are becoming transparent as PV penetration levels continue to increase. In this paper an analysis of solar system connected with the grid has been done. The system is subjected with two types of perturbations, i.e. variable load and the variable irradiance level which changes the output of the solar system. The design, modeling, and analysis of a grid-tied PV system are performed in the MATLAB software simulation environment. Solar cell works on the principle of photo voltaic effect, which has nonlinear voltage and current characteristics. These characteristics are improved with the help of maximum power point tracking (MPPT) controller. MPPT controller helps to feed the inverter with maximum power from the solar system. Results indicate that in the presence of grid disturbances the inverter can react dynamically to help restore the power system back to its normal state. A harmonic analysis was also performed indicating the inverter under study met the applicable power quality standards for distributed energy resources Anjali | Gourav Sharma"Power Quality Improvement in Grid Connected PV System" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-1 | Issue-4 , June 2017, URL: http://www.ijtsrd.com/papers/ijtsrd2196.pdf http://www.ijtsrd.com/engineering/electrical-engineering/2196/power-quality-improvement-in-grid-connected-pv-system/anjali
statcom-grid connected wind energy generating system for power qualityy impro...Venu Gopal
—Injection of the wind power into an electric grid affects the power quality. The performance of the wind turbine and thereby power quality are determined on the basis of measurements and the norms followed according to the guideline specified in International Electro-technical Commission standard, IEC-61400. The influence of the wind turbine in the grid system concerning the power quality measurements are-the active power, reactive power, variation of voltage, flicker, harmonics, and electrical behavior of switching operation and these are measured according to national/international guidelines. The paper study demonstrates the power quality problem due to installation of wind turbinewith the grid. In thisproposed scheme STATic COMpensator (STATCOM) is connected at a point of common coupling with a battery energy storage system (BESS) to mitigate the power quality issues. The battery energy storage is integrated to sustain the real power source under fluctuating wind power. The STATCOM control scheme for the grid connected wind energy generation system for power quality improvement is simulated using MATLAB/SIMULINK in power system block set. The effectiveness of the proposed scheme relives the main supply source from the reactivepower demand of the load and the induction generator. The development of the grid co-ordination rule and the scheme for improvement in power quality norms as per IEC-standard on the grid has been presented
A brief and basic presentation of interconnections of pwer system,it covers all the basic aspects of power system interconnection that how systems can be built with interconnections
Improvement of power quality has to be treated as a matter of at most importance in the open
market economy due to the increased use of non linear loads. Several devices have been used to mitigate
the power quality problems. Now a days researchers are concentrating on the use of FACT devices to
overcome power quality issues. Unified Power Quality Conditioner is one among such FACT devices upon
which this paper has concentrated for mitigating the Power Quality problems. Here a 3 phase 3 wire
UPQC is realised using MATLAB/SIMULINK to mitigate voltage sag and swell as well as to maintain
sinusoidal voltage and current at PCC irrespective of load dynamics.
Simulation and Analysis of a D-STATCOM for Load Compensation and Power Facto...IJMER
Power Generation and Transmission is a complex process, requiring the working of many
components of the power system in tandem to maximize the output. One of the main components to form
a major part is the reactive power in the system. It is required to maintain the voltage to deliver the
active power through the lines. Loads like motor loads and other loads require reactive power for their
operation. To improve the performance of ac power systems, we need to manage this reactive power in
an efficient way and this is known as reactive power compensation. In developing countries like India,
where the variation of power frequency and many such other determinants of power quality are
themselves a serious question, it is very vital to take positive steps in this direction.
The work presented here illustrates a method to compensate for the load reactive power using a
DSTATCOM
A DSTATCOM injects a current into the system to provide for the reactive component of the load
current. The validity of proposed method and achievement of desired compensation are confirmed by
the results of the simulation in MATLAB/ Simulink.
A Novel Technique for Enhancing Active and Reactive Power Quality for Renewab...IJMER
Renewable energy resources (RES) are being increasingly connected in distribution systems utilizing power electronic converters. This paper presents a novel control strategy for achieving maximum benefits from these grid-interfacing inverters when installed in 3-phase 4-wire distribution systems. The inverter is controlled to perform as a multi-function device by incorporating active power filter functionality. The inverter can thus be utilized as: 1) power converter to inject power generated from RES to the grid, and 2) shunt APF to compensate current unbalance, load current harmonics, load reactive power demand and load neutral current. All of these functions may be accomplished either individually or simultaneously. With such a control, the combination of grid-interfacing inverter and the 3-phase 4-wire linear/non-linear unbalanced load at point of common coupling appears as balanced linear load to the grid. This new control concept is demonstrated with extensive MATLAB/Simulink simulation studies and results.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Grid Interconnection of Renewable Energy Sources at the Distribution Level Wi...Pradeep Avanigadda
Renewable energy resources (RES) are being increasingly
connected in distribution systems utilizing power electronic
converters. This paper presents a novel control strategy for
achieving maximum benefits from these grid-interfacing inverters
when installed in 3-phase 4-wire distribution systems. The inverter
is controlled to perform as a multi-function device by incorporating
active power filter functionality. The inverter can thus be
utilized as: 1) power converter to inject power generated from
RES to the grid, and 2) shunt APF to compensate current unbalance,
load current harmonics, load reactive power demand and
load neutral current. All of these functions may be accomplished
either individually or simultaneously. With such a control, the
combination of grid-interfacing inverter and the 3-phase 4-wire
linear/non-linear unbalanced load at point of common coupling
appears as balanced linear load to the grid. This new control
concept is demonstrated with extensive MATLAB/Simulink simulation
studies and validated through digital signal processor-based
laboratory experimental results.
Index Terms—Active power filter
Power Quality Improvement at Distribution Level for Grid Connected Renewable ...IJERA Editor
The non-linear load current harmonics may result in voltage harmonics and can create a serious PQ problem in
the power system network. Active power filters (APF) are extensively used to compensate the load current
harmonics and load unbalance at distribution level. This results in an additional hardware cost. However, in this
project it has incorporated the features of APF in the conventional inverter interfacing renewable with the grid,
without any additional hardware cost. Here, the main idea is the maximum utilization of inverter rating which is
most of the time underutilized due to intermittent nature of RES. The grid-interfacing inverter can effectively be
utilized to perform the four important functions they are to transfer active power harvested from the renewable
resources (wind, solar, etc.), load reactive power demand support, current harmonics compensation at PCC and
current unbalance and neutral current compensation in case of 3-phase 4-wire system. Moreover, with adequate
control of grid-interfacing inverter, all the four objectives can be accomplished either individually or
simultaneously. The PQ constraints at the PCC can therefore be strictly maintained within the utility standards
without additional hardware cost.
With such a control, the combination of grid-interfacing inverter and the 3-phase 4-wire linear/non-linear
unbalanced load at point of common coupling appears as balanced linear load to the grid. This new control
concept is demonstrated with extensive MATLAB/Simulink simulation studies
A Novel control of a Grid-Interfacing Inverter to Improve the Quality of Powe...IJERA Editor
Renewable energy resources (RES) are being increas- ingly connected in distribution systems utilizing power electronic converters. This paper presents a novel control strategy for achieving maximum benefits from these grid-interfacing inverters when installed in 3-phase 4-wire distribution systems. The inverter is controlled to perform as a multi-function device by incorporating active power filter functionality. The inverter can thus be utilized as: 1) power converter to inject power generated from RES to the grid, and 2) shunt APF to compensate current unbalance, load current harmonics, load reactive power demand and load neutral current. All of these functions may be accomplished either individually or simultaneously. With such a control, the combination of grid-interfacing inverter and the 3-phase 4-wire linear/non-linear unbalanced load at point of common coupling appears as balanced linear load to the grid. This new control concept is demonstrated with extensive MATLAB/Simulink simulation studies and validated through digital signal processor-based laboratory experimental results.
Research Inventy : International Journal of Engineering and Scienceresearchinventy
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A Technique for Shunt Active Filter meld micro grid SystemIJERA Editor
The proposed system presents a control technique for a micro grid connected hybrid generation system ith case study interfaced with a three phase shunt active filter to suppress the current harmonics and reactive power present in the load using PQ Theory with ANN controller. This Hybrid Micro Grid is developed using freely renewable energy resources like Solar Photovoltaic (SPV) and Wind Energy (WE). To extract the maximum available power from PV panels and wind turbines, Maximum power point Tracker (MPPT) has been included. This MPPT uses the “Standard Perturbs and Observe” technique. By using PQ Theory with ANN Controller, the Reference currents are generated which are to be injected by Shunt active power filter (SAPF)to compensate the current harmonics in the non linear load. Simulation studies shows that the proposed control technique performs non-linear load current harmonic compensation maintaining the load current in phase with the source voltage.
Adaptive Fuzzy PID Based Control Strategy For 3Phase 4Wire Shunt Active Filte...IJERA Editor
This paper presents a new control strategy for controlling the shunt active power filter to compensate reactive
power and to reduce the unwanted harmonics in the grid current. Shunt active filter act as a current source which
is connected in parallel with a non-linear load and controlled to produce the required compensating current. The
proposed control strategy is based on the fuzzy PID controller which is used for determining the reference
compensating currents of the three-phase shunt active power filters. Simulations are carried out using
MATLAB/SIMULINK to verify the performance of the proposed controller. The output shows the controller has
fast dynamic response high accuracy of tracking DC voltage reference and robust to load parameters variations
Grid Connected PV System with Power Quality Improvement Using Intelligent Con...IJMTST Journal
The depletion of the fossil fuel resources and the global warming effects has led the world to think
seriously of other alternative sources of energy. So renewable energy resources (RES) are being connected to
the distribution systems, mostly done by using power electronic converters. But use of power electronic
converters and non-linear loads like at distribution level injects harmonics, which intern cause power quality
problems. Distribution static compensator (DSTATCOM) is very popular in compensating power problems for
nonlinear and unbalanced loads. Any change in the load affects the DC-link voltage (DCLV) directly.
Conventionally, a PI controller is used to maintain the DCLV to the reference value, but its transient response
is poor. So, fuzzy logic controller is proposed which shows better dynamic response. To trigger inverter HCC
is used. The proposed inverter with the control when connected to wind energy, helps the 3-phase 4-wire
linear/non-linear unbalanced load at point of common coupling appear as balanced linear load to the grid.
With MATLAB/Simulink simulation studies, the proposed control technique is demonstrated and evaluated
here.
4.power quality improvement in dg system using shunt active filterEditorJST
Injection of power generated by the wind turbine system into an electric grid mainly effects the power quality. The performance of this wind turbine and its power quality is determined on the basis of its measurement of power ratings as per IEEE standards. The influence of the wind turbine in the grid system concerning the power quality measurements are the active power, reactive power, variation of voltage, flicker, harmonics, and electrical behavior of switching operation. To mitigate the power quality problems this paper proposes the shunt compensator techniques. Here, the proposed system is verified experimentally using both STATCOM and TSC compensators. This control schemes for grid connected wind energy system is simulated using Matlab/Simulink.
Dynamic Power Factor Correction in a Non Linear Environmentiosrjce
Electric power quality mainly refers to maintaining a near sinusoidal power distribution bus voltage
at rated magnitude and frequency. In modern electric power supply distribution systems, there is a sharp rise in
use of both single phase and three-phase non-linear loads and due to these non-linear loads, non-sinusoidal
unbalanced current is drawn from ac mains resulting in harmonic injection, burden of reactive power, more
neutral currents and unbalanced loading of ac mains. In this paper the simulation of ideal shunt active power
filter is carried out to eliminate harmonics and also improving the power factor for three-phase, three-wire
system. In addition to this, simulation of shunt APF for three-phase, three-wire distribution system using time
domain p-q theory has been carried out to eliminate harmonics. Also an attempt is made to find out various
power quality problems and among these problems most prominent and frequently occurring problem
harmonics is analyzed and its causes, effects and mitigating or improving techniques are explained in detail. A
case study using ideal shunt AF and Shunt AF using p-q theory is also carried out in this paper.
Artificial neural network based unity power factor corrector for single phas...IJECEIAES
Due to the negative effects of the non-linear semiconductor devices and the passive electrical components (inductor and capacitor) in the converter circuits, and that are deteriorating the power factor (PF) and total harmonics distortion (THD) of grid current, this study proposes a novel unity PF correction controller based on a new algorithm of neural network to improve the performance of a single phase boost DC-DC converter with respect to the mentioned concerns. The controller guarantees stable load voltage. The PF corrector, firstly measures the phase shift between grid voltage and grid current waveforms, then through a new artificial neural network (ANN) algorithm, a suitable duty cycle is predicted to guide and control the converter to reduce the phase shift between grid voltage and grid current as possible to have maximum PF which is unity PF, and to improve the THD level of grid current. The proposed system is simulated and evaluated via Simulink of MATLAB, the simulation results are collected at constant duty cycle and at controlled duty cycle through the proposed PF controller using different loads. The presented PF controller guarantees the unity power factor, and enhances the grid alternating current THD.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
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Reactive Power Compensation in 132kv & 33kv Grid of Narsinghpur Areaijceronline
Power Sector is considered to be very important and priority sector as it leads to overall development of country. The cost of installation of new generating units is rising; hence generated electrical energy has to be utilized carefully and efficiently, which changes through each AC cycle. It is proposed to study the effect of group shunt compensation provided for the mix of rural and urban loads, catered from grid sub-stations in the district of Narsinghpur, to assess its adequacy and saving in transmission losses. An optimum combination of compensators which yields maximum benefits in the system shall be worked out. Load Flow Study for the effect of group shunt compensation provided on 132KV bus of 220KV sub-station Narsinghpur and on 33KV buses of 132KV sub stations Srinagar, Narsinghpur, Gadarwara and Burman sub-stations for the mix of rural and urban loads, catered from partial grid network in Narsinghpur district. If reactive power is supplied near the load, the line current can be reduced or minimized, reducing power losses and improving voltage regulation at the load terminals. The leading current drawn by the shunt capacitors compensates the lagging current drawn by the load. The selection of shunt capacitors depends on many factors, the most important of which is the amount of lagging reactive power taken by the load. Objective was to study the effect of group shunt compensation provided for the mix of rural and urban loads, catered from grid sub-stations in the district of Narsinghpur and to assess the adequacy and saving in transmission losses & to work out an optimum combination of compensators which yields maximum benefits in the system. Depending on the stages of 'ON' and 'OFF', operations to be carried out in various permutations and combinations of shunt compensators i.e. switchable capacitor banks provided on 132 KV bus of 220KV substation Narsinghpur and on 33KV buses of 132 KV substations
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Power Quality Improvement of Grid Interconnection of renewable Energy Based Distribution System
1. S. Bhanu Prakash Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 8( Version 7), August 2014, pp.134-139
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Power Quality Improvement of Grid Interconnection of renewable Energy Based Distribution System S. Bhanu Prakash1, Dr. T. Devaraju2 Pursuing M.Tech in SreeVidyanikethan Engineering College, Tirupati, Andhra Pradesh, India. Working as Professor, Dept. of EEE in SreeVidyanikethan Engineering College, Tirupati, Andhra Pradesh, India. Abstract This paper presents a grid interfacing inverter which compensates power quality problems and also interface Renewable Energy Sources with the help of electric grid. Renewable Energy Sources are being increasingly connected in distribution system utilizing power electronic converters. Grid interfacing inverter can be used: 1) To improve the transfer of active power harvested from RES; 2) To meet load reactive power demand support ; 3) To reduce current harmonics by incorporating the current harmonic compensator at point of common coupling(PCC) ; 4) current unbalance and neutral current compensation in case of 3-phase 4-wire system. The fuzzy logic can be used in many applications especially, when the process/models are complex to analyse by using classical methods. Mainly fuzzy logic controller is used to control DC capacitor voltage. Simulations are carried out using MATLAB/SIMULINK to verify the performance of the controller. The output shows the controller has fast dynamic response high accuracy of tracking DC voltage reference and robust to load parameters variations. IndexTerms— Active Power Filter,Distribution generation, fuzzy logic controller.
I. INTRODUCTION
THE green house gases (such as co2 ) absorbs the infrared radiation (IR) and confine the heat in the earth’s atmosphere.primarly, these gases emissions comes from the combustion of fossil fuels based on used energy. As the traditional fossil fuels are non- Renewable Energy Sources. The impact of these fossil fuels encouraged to find alternative energy sources to the fossil fuels. Therefore the RES became one of the important topics for research in the past years[1]. RES integrated at distribution level is termed as distribution generation(DG). As the utility of high penetration of intermittent RES in distribution systems constitute a threat to network in terms of stability,voltage regulation and power quality issues , DG systems are required to act in accordance with technical and regulatory frame works to protect secure, reliable and cost-effective operation of overall network. Hence DG systems can be actively controlled to enhance the system operation with improved power quality at PCC[2].
Extending use of power electronics based equipment and non-linear loads at PCC generate harmonic currents may weakening the PQ. Due to the wide spread use of non-linear loads significant amounts of harmonic currents are being injected into power systems. These harmonic currents flows through the power systemimpedance which causes harmonic currents to be drawn by other loads connected at PCC. The persistence of current and voltage harmonics in power system increases losses in the lines, decrease the power factor and may cause timing errors in sensitive electronic equipment’s. Balanced 3-phase non-linear loads such as motor drivers, silicon controlled rectifiers (SCR), large uninterruptible power supplies (UPS) produce harmonic currents and voltages which are positive- sequence harmonics like 7th, 13th, etc. and negative- sequence harmonics like 5th, 11th, etc. Single phase non-linear loads such as switch-mode power supplies in computer equipment produce produce harmonic currents and voltages which are third order zero- sequence harmonics, triplen harmonics like 3rd, 9th, 15th, 21st, etc. Unlike positive and negative- sequence harmonic currents, triplen harmonic currents do not cancel but add arithmetically at the neutral bus. This result’sthe neutral current that touches magnitudes as high as 1.73 times the phase current. In addition to the risk of cables and transformers overheating, the third harmonic can recede energy efficiency [3].
The method of current harmonics reduction reduces passive LC filters which are simple and low cost. However, these filters have drawbacks as well like large size, tuning and risk of resonance problems. As harmonic pollution is severe in power networks, power system engineer developed dynamic and adjustable solutions to the power quality problems. Such equipment is known as Active Filters (AF’s) [4]. These filters are used to compensate the load current harmonics and load unbalance at
RESEARCH ARTICLE OPEN ACCESS
2. S. Bhanu Prakash Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 8( Version 7), August 2014, pp.134-139
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Fig. 1.Schematic of proposed renewable based distribution generation system.
distribution level and this results in additional cost.In this paper, the features of APF [5] are incorporated in the conventional inverter interfacing renewable using the grid without any additional cost. This inverter is known as ‖Grid interfacing inverter‖ and this is incorporated with active power filter functionality to control the performance of malfunction device. Hence this inverter can be used as: 1) power converter to inject power generated from RES to the grid, and ;2) shunt APF to compensate current unbalance, load current harmonics, load reactive power demand and load neutral current. And these functions can be achieved either independently or simultaneously.
II. SYSTEM INTERPRETATION Fig.1 shows the proposed system consists of RES connected to the dc-link of a grid-interfacing inverter. As voltage source inverter interfaces the renewable energy source to the grid and delivers the generated power, it is considered as a key element of DG system. The RES may be a DC source or an AC source with rectifier coupled to dc-link. Usually the variable speed wind turbines generate power at variable ac voltage but the fuel cell and photovoltaic energy sources generate power at variable low dc voltage. Thus the power generated from these renewable sources need power conditioning before connecting to dc-link. The dc- capacitor allows independent control of converters on either side of dc-link and decouples the RES from the grid [6].
Fig. 2.Simulink diagram of wind farm.
Fig. 3. DC-link equivalent diagram
A. DC-Link Voltage and Power Control Operation The power generated due to the intermittent or irregular nature of RES is of variable nature. The dc- link plays an important role in transferring this power from renewable energy source to the grid. Renewable Energy Sources are entitled as current sources connected to the dc-link of a grid-interfacing inverter. Fig. 2 shows the structured representation of power transfer from the RES to the grid through dc-link.
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The current injected at voltage level by renewable into dc-link can be calculated as Idc1=PRES/Vdc (1) Where PRES is power generated from RES. The current flow from other dc-link can be characterized as, Idc2=Pinv/Vdc=(Pg+Ploss)/Vdc(2) Where Pinv is the total power available at grid- interfacing inverter side PG is the active power supplied to the grid and Ploss is the inverter losses, if inverter losses are negligible then Pres=Pg.
B. Control Scenario Fig.4 shows the control diagram of grid- interfacing inverter for a 3-phase 4-wire system. The fourth leg of inverter is used to compensate the neutral current of load. The aim of proposed approach I to regulate the power at PCC during: 1) PRES=0; 2)PRes<PL(Total Load Power); 3) PRES>PL; The inverteralways draws/supplies necessary active power from/to the grid during the power management operation. The given control approach compensates harmonics, unbalance, and neutral current when the load connected to PCC is non-linear or unbalanced or the combination of both.
Ua=sin(Ɵ) (3) Ub=sin(Ɵ-2π/3)(4) Uc=sin(Ɵ+2π/3)(5) The actual dc-link voltage (Vdc) is sensed and passed through a first-order low pass filter (LPF) to eliminate the presence of switching ripples on the dc- link voltage and in the generated reference current signals. To maintain a constant dc-link voltage under varying generation and load conditions, the difference of this fltered dc-link voltage and reference dc-link voltage (Vdc*) is given to a fuzzy logic controller.The instantaneous values of reference three phase grid currents can be calculated as Ia*=Im.ua(6) Ib*=Im.ub(7) Ic*=Im.uc(8) The remaining neutral current due to the loads connected to the neutral conductor should be compensated by forth leg of grid-interfacing inverter and should be drawn from the grid. In alternate words, the reference current for the grid neutral current is considered as zero and can be expressed as
In*=0 (9)
Fig. 4. Block diagram representation of grid interfacing inverter control.
The duty ratio of inverter switches are varied in a power cycle such that the combination of load and Thus the output of dc-link voltage regulator results in an active current Im. The multiplication of active current component (Im) with unity grid voltage vector templates (Ua, Ub and Uc) generates the reference grid currents (in*) is put to zero, being the instantaneous sum of balanced grid currents the grid synchronizing angle (θ) is obtained from phase locked loop (PLL) is used to generate unit vector template. The reference grid currents are compared with actual grid currents (Ia*,Ib*,Ic* , In*) to compute the current errors as: Ia error*=Ia*.Ia(10) Iberrr*=Ib*.Ib(11) Ic error*=Ic*.Ic(12)
The current errors are given to hysteresis current controller. Fig. 4 shows the gate drivers of grid
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interfacing inverter, P1 to P8 are the switching pulses generated from the hysteresis controller.
C. FUZZY LOGIC CONTROLLER(FLC)
The disadvantage of PI controller is its inability to react to abrupt changes in the error signal, ε, because it is only capable of determining the instantaneous value of the error signal without considering the change of the rise and fall of the error, which in mathematical terms is the derivative of the error denoted as Δε. To solve this problem, The output control signal can be determined in an inference engine with a rule in the form of : "IF ε is ....... AND Δε is ......., THEN output is ........" Hence, the value of output can be changed accordingly to the value of error signal, ε, and the rate-of-errorΔε thetrail and error methods are used to determine the structure and value of the rule base and it is also done through experimentation.
Fuzzy logic control [7] as shown in the fig.5 is
Fig. 5. FLC structure.
proposed. The disadvantage of PI controller Is its inability to react to abrupt changes in the error Signal, ε, as it is only capable of determining the ins- tantaneous value of the error signal without consid- ering the change of rise and fall of the error. This change in rise and fall of error is mathematically derived as Δε. Fig.5 shows the basic representation of Fuzzy logic control (FLC) to resolve the problem
Fig. 6. Membership functions of input error(Ɛ)
Fig. 7. Membership functions of input change in error(ΔƐ)
TABLE1.FLC Rule Base
All the variables of fuzzy subsets for the inputs ε and Δε can be defined as (NB, NM, NS, Z, PS, PM, PB). Fig.6&7 represents the membership functions of inputs ε and Δε. Table1 illustrates Fuzzy Control Rule. SWITCHING CONTROL
The hysteresis control is used to keep the controlled current inside a defined band around the references as shown in the Fig. 4. The status for the switches can be determined according to the error. When the current increases and error exceeds a certain positive value, the status of switches changes and the currentbegins to decrease until the error reaches a certain negative Before t=0.8s, the grid interfacing inverter is not connected to network, henceValue and again the status of switches change. Based on hysteresis strategies, the non-linear ones allow faster dynamic response and better robustness with respect to the variation of the non-linear load
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compared with linear controllers. A drawback [8] of the hysteresis strategies is the switching frequency is not constant and can generate a large side harmonics. III. SIMULATION RESULTS To verify the proposed control strategy, an extensive simulation strategy is carried out using MATLAB/Simulink. The 4-leg grid interfacing inverter is actively controlled under varying renewable generating condition in order to achieve balanced sinusoidal grid currents at unity power factor.
Fig. 8. Simulation results : (a) grid voltages,(b) grid currents,(c) Load currents, (d) inverter currents Fig.8 shows the waveforms of grid voltages, grid currents, unbalanced load current and inverter currents. Fig. 9 shows the corresponding active and reactive of grid (PQ grid), load (PQ load) and inverter (PQ inv). Positive values of grid active- reactive powers and inverter active-reactive powers imply that these powers flow from grid side towards PCC and from inverter towards PCC, correspondingly. The active and reactive powers absorbed by the load are denoted by positive signs.the grid currents in Fig.8 (b) are same as unbalanced nonlinear load currents Fig.8(c).
At t=0.8s, the grid interfacing inverter is now connected to network. Fig.8 (b) shows the grid current starts changing to sinusoidal balanced from unbalanced nonlinear current. At this instant, active power injected by the inverter from RES is shown in Fig.9. The load power demand is less than the generated power and the additional power in fed back to the grid. The grid is receiving power from RES after 0.85s and it is indicated by –ve sign. By considering the load power demand as constant, the power generated from RES at t=0.85s is increased to verify the system performance under variable power generation and hence it increases the magnitude of inverter current. At t=0.95s generation of power from RES is reduced. The active and re-active power flows between the inverter, load and grid during increase and decrease of energy generation from RES can be noticed from Fig. 9.
Fig. 9. Simulation results :(a) PQ grid, (b) PQ load, (c)PQ inverter, (d) dc link voltage using Fuzzy Logic Controller.
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IV. CONCLUSION This paper presented the control of grid- interfacing inverter to improve the power quality at PCC for a 3-phase 4-wire DG System. Grid- interfacing inverter can be effectively utilized for power conditioning without affecting its normal operation of power transfer. This inverter can be utilized to inject the power generated from RES to the grid and/or to operate as a shunt Active Power Filter (APF). This process eliminates the need for additional power conditioning equipment to improve of power at PCC. MATLAB/Simulink simulation and Fuzzy logic based results have validated this process and thus this inverter can be utilized as a multi- function device. REFERENCES
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