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.
Unified power quality conditioner for compensating power quality problem adIAEME Publication
This document describes a proposed Adaptive Neuro-Fuzzy Inference System (ANFIS) based Unified Power Quality Conditioner (UPQC) to improve power quality compensation performance. A UPQC uses two voltage source inverters to compensate for both voltage and current disturbances but has high DC link capacitor discharge times. The proposed system adds an ANFIS device to generate a bias voltage that maintains the DC link voltage at a lower level. ANFIS combines neural networks and fuzzy logic to approximate nonlinear functions from numerical and linguistic data. The generated fuzzy rules are trained using a neural network to produce the desired output. Analysis shows the proposed ANFIS-based UPQC provides better power quality compensation than controllers using neural networks,
Design of UPQC with Minimization of DC Link voltage for the Improvement of Po...IDES Editor
This document describes a proposed design for a Unified Power Quality Conditioner (UPQC) that uses fuzzy logic control to minimize DC link voltage fluctuations and improve power quality. The UPQC combines series and shunt inverters to compensate for voltage sags/swells, unbalanced voltages, harmonics, and reactive power. Fuzzy logic controllers are used to stabilize the DC link voltage and balance active power between the inverters. Simulation results show the fuzzy logic control provides better DC link voltage regulation compared to PI control, improving the UPQC's ability to compensate for power quality issues.
Simulation of unified power quality conditioner for power quality improvement...Alexander Decker
1) The document discusses the simulation of a Unified Power Quality Conditioner (UPQC) using fuzzy logic and neural networks to improve power quality.
2) A UPQC configuration is presented that uses a fuzzy logic controller and is compared to an artificial neural network controller.
3) Simulation results in Matlab/Simulink show that the fuzzy logic controller compensates 75% of voltage sags during faults while the neural network controller compensates 95% of voltage sags.
Power quality conditioners are devices used in smart grids to improve the quality of power delivered to loads. They ensure efficient power transfer, isolate grids from disturbances, convert DC to AC, and integrate with energy storage. Common types include distribution static compensators (DSTATCOMs), active power filters, and unified power quality conditioners (UPQCs). DSTATCOMs regulate voltage and compensate for reactive power. Active power filters compensate for harmonics and reactive power. UPQCs combine series and shunt filters to compensate for both voltage and current issues. Power quality conditioners are important for integrating renewable energy and ensuring loads function properly in smart grids.
This document discusses a project submitted to fulfill the requirements for a Bachelor of Electrical Engineering degree. The project aims to improve power quality using a Unified Power Quality Conditioner (UPQC). The UPQC integrates series and shunt active power filters to maintain power quality at the point of installation in power distribution or industrial power systems. It can compensate for disturbances in AC systems. The document presents the compensation principles and control strategies of the UPQC using PI and fuzzy logic control simulations in MATLAB/Simulink. The multivariable controller presents better results in terms of total harmonic distortion values.
This document presents information on power quality conditioners. It defines power quality and discusses various types of power quality conditioners, including DSTATCOM, active power filters, and UPQC. DSTATCOM uses a voltage source converter to regulate voltage and improve power quality. Active power filters come in shunt, series, and hybrid configurations to compensate for reactive power, harmonics, and voltage issues. UPQC combines shunt and series active power filters to compensate for both voltage and current problems. Maintaining good power quality is important for economic system operation.
Power quality improvement using upqc with soft computing method: Fuzzy logicSakti Prasanna Muduli
Now a days problems regarding power quality is more in large inter connected power systems. There are many method to mitigate these problems but using the latest most efficient compensation method is some what impressive. Here is the brief explanations regarding UPQC using soft computing method(fuzzy logic). This was my academic project along with my friends.
A Voltage Controlled Dstatcom for Power Quality Improvementiosrjce
Due to increasing complexity in the power system, voltage sag is becoming one of the most significant
power quality problems. Voltage sag is a short reduction voltage from nominal voltage, occurs in a short time.
If the voltage sags exceed two to three cycles, then manufacturing systems making use of sensitive electronic
equipments are likely to be affected leading to major problems. It ultimately leads to wastage of resources (both
material and human) as well as financial losses. This is possible only by ensuring that uninterrupted flow of
power is maintained at proper voltage levels. This project tends look at the solving the sag problems by using
custom power devices such as Distribution Static compensator (D-STATCOM).Proposed scheme follows a new
algorithm to generate reference voltage for a distribution static compensator (DSTATCOM) operating in
voltage-control mode. The proposed scheme ensures that unity power factor (UPF) is achieved at the load
terminal during nominal operation, which is not possible in the traditional method. Also, the compensator
injects lower currents therefore, reduces losses in the feeder and voltage-source inverter. Further, a saving in
the rating of DSTATCOM is achieved which increases its capacity to mitigate voltage sag. Nearly UPF is
maintained, while regulating voltage at the load terminal, during load change. The state-space model of
DSTATCOM is incorporated with the deadbeat predictive controller for fast load voltage regulation during
voltage disturbances. With these features, this scheme allows DSTATCOM to tackle power-quality issues by
providing power factor correction, harmonic elimination, load balancing, and voltage regulation based on the
load requirement.
Unified power quality conditioner for compensating power quality problem adIAEME Publication
This document describes a proposed Adaptive Neuro-Fuzzy Inference System (ANFIS) based Unified Power Quality Conditioner (UPQC) to improve power quality compensation performance. A UPQC uses two voltage source inverters to compensate for both voltage and current disturbances but has high DC link capacitor discharge times. The proposed system adds an ANFIS device to generate a bias voltage that maintains the DC link voltage at a lower level. ANFIS combines neural networks and fuzzy logic to approximate nonlinear functions from numerical and linguistic data. The generated fuzzy rules are trained using a neural network to produce the desired output. Analysis shows the proposed ANFIS-based UPQC provides better power quality compensation than controllers using neural networks,
Design of UPQC with Minimization of DC Link voltage for the Improvement of Po...IDES Editor
This document describes a proposed design for a Unified Power Quality Conditioner (UPQC) that uses fuzzy logic control to minimize DC link voltage fluctuations and improve power quality. The UPQC combines series and shunt inverters to compensate for voltage sags/swells, unbalanced voltages, harmonics, and reactive power. Fuzzy logic controllers are used to stabilize the DC link voltage and balance active power between the inverters. Simulation results show the fuzzy logic control provides better DC link voltage regulation compared to PI control, improving the UPQC's ability to compensate for power quality issues.
Simulation of unified power quality conditioner for power quality improvement...Alexander Decker
1) The document discusses the simulation of a Unified Power Quality Conditioner (UPQC) using fuzzy logic and neural networks to improve power quality.
2) A UPQC configuration is presented that uses a fuzzy logic controller and is compared to an artificial neural network controller.
3) Simulation results in Matlab/Simulink show that the fuzzy logic controller compensates 75% of voltage sags during faults while the neural network controller compensates 95% of voltage sags.
Power quality conditioners are devices used in smart grids to improve the quality of power delivered to loads. They ensure efficient power transfer, isolate grids from disturbances, convert DC to AC, and integrate with energy storage. Common types include distribution static compensators (DSTATCOMs), active power filters, and unified power quality conditioners (UPQCs). DSTATCOMs regulate voltage and compensate for reactive power. Active power filters compensate for harmonics and reactive power. UPQCs combine series and shunt filters to compensate for both voltage and current issues. Power quality conditioners are important for integrating renewable energy and ensuring loads function properly in smart grids.
This document discusses a project submitted to fulfill the requirements for a Bachelor of Electrical Engineering degree. The project aims to improve power quality using a Unified Power Quality Conditioner (UPQC). The UPQC integrates series and shunt active power filters to maintain power quality at the point of installation in power distribution or industrial power systems. It can compensate for disturbances in AC systems. The document presents the compensation principles and control strategies of the UPQC using PI and fuzzy logic control simulations in MATLAB/Simulink. The multivariable controller presents better results in terms of total harmonic distortion values.
This document presents information on power quality conditioners. It defines power quality and discusses various types of power quality conditioners, including DSTATCOM, active power filters, and UPQC. DSTATCOM uses a voltage source converter to regulate voltage and improve power quality. Active power filters come in shunt, series, and hybrid configurations to compensate for reactive power, harmonics, and voltage issues. UPQC combines shunt and series active power filters to compensate for both voltage and current problems. Maintaining good power quality is important for economic system operation.
Power quality improvement using upqc with soft computing method: Fuzzy logicSakti Prasanna Muduli
Now a days problems regarding power quality is more in large inter connected power systems. There are many method to mitigate these problems but using the latest most efficient compensation method is some what impressive. Here is the brief explanations regarding UPQC using soft computing method(fuzzy logic). This was my academic project along with my friends.
A Voltage Controlled Dstatcom for Power Quality Improvementiosrjce
Due to increasing complexity in the power system, voltage sag is becoming one of the most significant
power quality problems. Voltage sag is a short reduction voltage from nominal voltage, occurs in a short time.
If the voltage sags exceed two to three cycles, then manufacturing systems making use of sensitive electronic
equipments are likely to be affected leading to major problems. It ultimately leads to wastage of resources (both
material and human) as well as financial losses. This is possible only by ensuring that uninterrupted flow of
power is maintained at proper voltage levels. This project tends look at the solving the sag problems by using
custom power devices such as Distribution Static compensator (D-STATCOM).Proposed scheme follows a new
algorithm to generate reference voltage for a distribution static compensator (DSTATCOM) operating in
voltage-control mode. The proposed scheme ensures that unity power factor (UPF) is achieved at the load
terminal during nominal operation, which is not possible in the traditional method. Also, the compensator
injects lower currents therefore, reduces losses in the feeder and voltage-source inverter. Further, a saving in
the rating of DSTATCOM is achieved which increases its capacity to mitigate voltage sag. Nearly UPF is
maintained, while regulating voltage at the load terminal, during load change. The state-space model of
DSTATCOM is incorporated with the deadbeat predictive controller for fast load voltage regulation during
voltage disturbances. With these features, this scheme allows DSTATCOM to tackle power-quality issues by
providing power factor correction, harmonic elimination, load balancing, and voltage regulation based on the
load requirement.
The document discusses power quality issues caused by nonlinear loads and various power quality conditioners used to address these issues. It introduces the unified power quality conditioner (UPQC), which integrates series and shunt active power filters to compensate for both voltage and current-related power quality problems. The UPQC can mitigate issues like harmonics, voltage sags and swells, reactive power, power factor, and load unbalance. It operates by injecting compensating currents from the shunt filter and generating compensating voltages from the series filter to regulate the supply voltage and current waveforms seen by the load. The UPQC provides a comprehensive solution for improving power quality in distribution systems.
Integration of upqc for power quality improvement in distributedNagaraj Madival
This document reviews research on integrating a Unified Power Quality Conditioner (UPQC) in distributed generation networks. A UPQC can compensate for voltage disturbances, current harmonics, reactive power, and power factor issues. Two main integration techniques are discussed: 1) Connecting distributed generators to the UPQC's DC link, which allows voltage interruption compensation and active power transfer but with higher control complexity. 2) Having separate UPQC and distributed generator systems, which is easier to control but may not provide voltage interruption compensation or islanding mode operation. The document also discusses using a UPQC across two distribution feeders to maintain constant voltages during faults or interruptions.
This presentation discusses power quality improvement in small isolated distribution systems using a DSTATCOM (Distribution Static Compensator) with fuzzy logic control. It aims to regulate voltage, reduce harmonics, correct power factor, and balance loads. The system contains a DSTATCOM connected in parallel to regulate voltage and correct power factor as loads change. Simulation results show the DSTATCOM improves power quality by correcting power factor, balancing loads, and regulating voltage under different load conditions using both PI and fuzzy logic controllers. The presentation concludes fuzzy logic control of a DSTATCOM is effective for power quality improvement in small isolated power systems like ships, islands, and remote generation sites.
This document discusses using a D-STATCOM (Distribution Static Synchronous Compensator) to improve power quality and voltage regulation in a photovoltaic (PV) distribution system. The objectives are to analyze the effects of nonlinear loads, study existing harmonics mitigation methods, and propose a best method for compensating reactive power and mitigating current harmonics. It presents the contents, introduces issues like harmonics from power electronic devices and reactive power disturbances. It then describes the operation, topology and components of a D-STATCOM and PV system. MATLAB models of the grid-connected PV system with and without D-STATCOM are presented, showing the D-STATCOM improves power factor and regulates the voltage.
An improved iupqc controller to provide additional grid voltage regulation as...LeMeniz Infotech
An improved iupqc controller to provide additional grid voltage regulation as a statcom
To Get this projects Call : 9566355386 / 99625 88976
Visit : www.lemenizinfotech.com / www.ieeemaster.com
Mail : projects@lemenizinfotech.com
UPQC a novel method to efficiently utilize Sustainable / Alternate Energy Sources is a presentation about power quality issues and solutions. It discusses different power quality problems such as voltage sags, swells, harmonics, and reactive power issues. It then introduces several custom power devices that can address these problems including the STATCOM, DVR, and UPQC. The UPQC is described as an active series-shunt power line conditioner that can compensate for various power quality issues such as voltage sags/swells, imbalance, flicker, and harmonics. The presentation concludes by discussing future trends in power semiconductor switches and the balanced application of these new technologies.
This document describes a project to improve power quality using a Unified Power Quality Conditioner (UPQC). The UPQC compensates for voltage disturbances and improves current quality using active power filters. It maintains the load voltage despite supply variations. The document outlines the objectives, introduces UPQC components like the shunt and series active power filters, and describes the multivariable controller and Simulink model. The UPQC provides advantages like reduced harmonics, improved waveform quality, and balanced power factor.
Power quality-disturbances and monitoring SeminarSurabhi Vasudev
The document provides an overview of power quality monitoring and automatic power quality disturbance classification. It defines power quality and discusses increased interest in power quality. It describes various power quality disturbances like voltage fluctuations, harmonics, sags, and swells. It then discusses automatic power quality disturbance classifiers which use techniques like segmentation, feature extraction, and classification to identify different disturbance types. Neural networks and expert systems are presented as methods for automatic classification. The document emphasizes the importance of power quality monitoring and classification systems.
Harmonics created by nonlinear loads such as arc furnaces, cycloconverters and motor drives destroys the power quality in the system. They not only affect the working of adjacent loads but also shorten the life of power equipment by creating excessive losses. ‘Shunt Active Power Filter’ is a modern addition to family of compensating devices. It has superior qualities over its contemporaries namely SVCs and STATCOMs. It not only mitigates harmonics within the allowable limits defined by IEEE Std 519-1992, but also compensates unbalancing and reactive power in the system. Consequently, only active power is supplied by the source thus power factor approaches unity. A fully functional Simulink model of Shunt Active Power Filter has been designed based on ‘Instantaneous Power Theory’ or ‘p-q Theory’. The results of simulation comply with all the features described by the theory, justifying employment of SAPF in the industry.
The document discusses using a STATCOM and battery energy storage system to improve power quality from a grid-connected wind energy system. It proposes a control scheme where the STATCOM injects current to cancel out reactive and harmonic parts of current from the induction generator and nonlinear load. It presents the system topology, operation, bang-bang controller for the STATCOM, and simulation results showing the STATCOM reduces total harmonic distortion of source current from 4.06% to 0.40%, improving power quality. The document concludes that the STATCOM-BESS control system eliminates harmonic load current and maintains unity power factor and in-phase voltages and currents at the source.
power quality improvement in distrution system using D statcom7867867869
The document discusses using a D-STATCOM device to improve power quality issues in distribution systems, such as voltage sags, harmonic distortion, and low power factor. A D-STATCOM injects current into the system using a voltage source converter to regulate voltage and mitigate sags. It can also absorb or generate reactive power to improve power factor and eliminate current harmonics. Simulation results showed the D-STATCOM is effective at mitigating voltage sags and improving power factor when combined with an LCL passive filter.
This document appears to be a syllabus for a course on power quality. It includes 5 units: introduction to power quality, voltage sags and interruptions, over voltages, harmonics, and power quality monitoring. The introduction defines power quality and discusses various power quality issues like harmonics, voltage fluctuations, transients, and imbalance. It also explains why power quality is important for utilities and customers.
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.
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.
This document presents a project on improving power quality using a multi converter unified power quality conditioner (MC-UPQC). The project is presented by a student under the guidance of a professor. The MC-UPQC uses voltage source converters connected back-to-back to compensate for supply voltage and load current imperfections. It can also compensate for power quality issues across multiple feeders by sharing compensation capabilities. The document outlines the objectives, existing systems, proposed MC-UPQC system, literature review, problem formation, test system design, simulation results and conclusions.
Enhancement of power quality in distribution system by using D-STATCOMEng Ahmed Salad Osman
The document is a thesis submitted by three students for their Bachelor's degree in Electrical Engineering. It discusses enhancing power quality in a distribution system using a D-STATCOM (Distribution Static Compensator). The thesis is classified as confidential and contains restricted information as specified by the University of Hormuud. The students declare the work as their own, and acknowledge the university's rights over the thesis.
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.
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.
with the help of web based power quality monitoring system we can control and manage the data flow of electrical quantity and control the improve the quality of the power system in grid
This document presents a study on using a Distribution Static Compensator (DSTATCOM) to improve power quality issues like voltage sags and swells. It begins with an introduction to power quality problems such as voltage sags, swells, harmonics and transients. It then discusses different custom power devices that can be used as solutions, focusing on DSTATCOM. The document presents the configuration, modelling and control of a DSTATCOM. It proposes a control scheme for DSTATCOM and presents simulation results demonstrating its ability to regulate voltage during sags and improve power factor. The conclusion states that the proposed DSTATCOM scheme can effectively mitigate various power quality issues related to voltage and current.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
The document discusses power quality issues caused by nonlinear loads and various power quality conditioners used to address these issues. It introduces the unified power quality conditioner (UPQC), which integrates series and shunt active power filters to compensate for both voltage and current-related power quality problems. The UPQC can mitigate issues like harmonics, voltage sags and swells, reactive power, power factor, and load unbalance. It operates by injecting compensating currents from the shunt filter and generating compensating voltages from the series filter to regulate the supply voltage and current waveforms seen by the load. The UPQC provides a comprehensive solution for improving power quality in distribution systems.
Integration of upqc for power quality improvement in distributedNagaraj Madival
This document reviews research on integrating a Unified Power Quality Conditioner (UPQC) in distributed generation networks. A UPQC can compensate for voltage disturbances, current harmonics, reactive power, and power factor issues. Two main integration techniques are discussed: 1) Connecting distributed generators to the UPQC's DC link, which allows voltage interruption compensation and active power transfer but with higher control complexity. 2) Having separate UPQC and distributed generator systems, which is easier to control but may not provide voltage interruption compensation or islanding mode operation. The document also discusses using a UPQC across two distribution feeders to maintain constant voltages during faults or interruptions.
This presentation discusses power quality improvement in small isolated distribution systems using a DSTATCOM (Distribution Static Compensator) with fuzzy logic control. It aims to regulate voltage, reduce harmonics, correct power factor, and balance loads. The system contains a DSTATCOM connected in parallel to regulate voltage and correct power factor as loads change. Simulation results show the DSTATCOM improves power quality by correcting power factor, balancing loads, and regulating voltage under different load conditions using both PI and fuzzy logic controllers. The presentation concludes fuzzy logic control of a DSTATCOM is effective for power quality improvement in small isolated power systems like ships, islands, and remote generation sites.
This document discusses using a D-STATCOM (Distribution Static Synchronous Compensator) to improve power quality and voltage regulation in a photovoltaic (PV) distribution system. The objectives are to analyze the effects of nonlinear loads, study existing harmonics mitigation methods, and propose a best method for compensating reactive power and mitigating current harmonics. It presents the contents, introduces issues like harmonics from power electronic devices and reactive power disturbances. It then describes the operation, topology and components of a D-STATCOM and PV system. MATLAB models of the grid-connected PV system with and without D-STATCOM are presented, showing the D-STATCOM improves power factor and regulates the voltage.
An improved iupqc controller to provide additional grid voltage regulation as...LeMeniz Infotech
An improved iupqc controller to provide additional grid voltage regulation as a statcom
To Get this projects Call : 9566355386 / 99625 88976
Visit : www.lemenizinfotech.com / www.ieeemaster.com
Mail : projects@lemenizinfotech.com
UPQC a novel method to efficiently utilize Sustainable / Alternate Energy Sources is a presentation about power quality issues and solutions. It discusses different power quality problems such as voltage sags, swells, harmonics, and reactive power issues. It then introduces several custom power devices that can address these problems including the STATCOM, DVR, and UPQC. The UPQC is described as an active series-shunt power line conditioner that can compensate for various power quality issues such as voltage sags/swells, imbalance, flicker, and harmonics. The presentation concludes by discussing future trends in power semiconductor switches and the balanced application of these new technologies.
This document describes a project to improve power quality using a Unified Power Quality Conditioner (UPQC). The UPQC compensates for voltage disturbances and improves current quality using active power filters. It maintains the load voltage despite supply variations. The document outlines the objectives, introduces UPQC components like the shunt and series active power filters, and describes the multivariable controller and Simulink model. The UPQC provides advantages like reduced harmonics, improved waveform quality, and balanced power factor.
Power quality-disturbances and monitoring SeminarSurabhi Vasudev
The document provides an overview of power quality monitoring and automatic power quality disturbance classification. It defines power quality and discusses increased interest in power quality. It describes various power quality disturbances like voltage fluctuations, harmonics, sags, and swells. It then discusses automatic power quality disturbance classifiers which use techniques like segmentation, feature extraction, and classification to identify different disturbance types. Neural networks and expert systems are presented as methods for automatic classification. The document emphasizes the importance of power quality monitoring and classification systems.
Harmonics created by nonlinear loads such as arc furnaces, cycloconverters and motor drives destroys the power quality in the system. They not only affect the working of adjacent loads but also shorten the life of power equipment by creating excessive losses. ‘Shunt Active Power Filter’ is a modern addition to family of compensating devices. It has superior qualities over its contemporaries namely SVCs and STATCOMs. It not only mitigates harmonics within the allowable limits defined by IEEE Std 519-1992, but also compensates unbalancing and reactive power in the system. Consequently, only active power is supplied by the source thus power factor approaches unity. A fully functional Simulink model of Shunt Active Power Filter has been designed based on ‘Instantaneous Power Theory’ or ‘p-q Theory’. The results of simulation comply with all the features described by the theory, justifying employment of SAPF in the industry.
The document discusses using a STATCOM and battery energy storage system to improve power quality from a grid-connected wind energy system. It proposes a control scheme where the STATCOM injects current to cancel out reactive and harmonic parts of current from the induction generator and nonlinear load. It presents the system topology, operation, bang-bang controller for the STATCOM, and simulation results showing the STATCOM reduces total harmonic distortion of source current from 4.06% to 0.40%, improving power quality. The document concludes that the STATCOM-BESS control system eliminates harmonic load current and maintains unity power factor and in-phase voltages and currents at the source.
power quality improvement in distrution system using D statcom7867867869
The document discusses using a D-STATCOM device to improve power quality issues in distribution systems, such as voltage sags, harmonic distortion, and low power factor. A D-STATCOM injects current into the system using a voltage source converter to regulate voltage and mitigate sags. It can also absorb or generate reactive power to improve power factor and eliminate current harmonics. Simulation results showed the D-STATCOM is effective at mitigating voltage sags and improving power factor when combined with an LCL passive filter.
This document appears to be a syllabus for a course on power quality. It includes 5 units: introduction to power quality, voltage sags and interruptions, over voltages, harmonics, and power quality monitoring. The introduction defines power quality and discusses various power quality issues like harmonics, voltage fluctuations, transients, and imbalance. It also explains why power quality is important for utilities and customers.
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.
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.
This document presents a project on improving power quality using a multi converter unified power quality conditioner (MC-UPQC). The project is presented by a student under the guidance of a professor. The MC-UPQC uses voltage source converters connected back-to-back to compensate for supply voltage and load current imperfections. It can also compensate for power quality issues across multiple feeders by sharing compensation capabilities. The document outlines the objectives, existing systems, proposed MC-UPQC system, literature review, problem formation, test system design, simulation results and conclusions.
Enhancement of power quality in distribution system by using D-STATCOMEng Ahmed Salad Osman
The document is a thesis submitted by three students for their Bachelor's degree in Electrical Engineering. It discusses enhancing power quality in a distribution system using a D-STATCOM (Distribution Static Compensator). The thesis is classified as confidential and contains restricted information as specified by the University of Hormuud. The students declare the work as their own, and acknowledge the university's rights over the thesis.
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.
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.
with the help of web based power quality monitoring system we can control and manage the data flow of electrical quantity and control the improve the quality of the power system in grid
This document presents a study on using a Distribution Static Compensator (DSTATCOM) to improve power quality issues like voltage sags and swells. It begins with an introduction to power quality problems such as voltage sags, swells, harmonics and transients. It then discusses different custom power devices that can be used as solutions, focusing on DSTATCOM. The document presents the configuration, modelling and control of a DSTATCOM. It proposes a control scheme for DSTATCOM and presents simulation results demonstrating its ability to regulate voltage during sags and improve power factor. The conclusion states that the proposed DSTATCOM scheme can effectively mitigate various power quality issues related to voltage and current.
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Matlab Simulink in Three-Phase Fault Analysis on Transmission linepamu17
When different types of fault occurs in power system then in the process of transmission line fault analysis, determination of bus
voltage and the rms line current are possible. While consulting with the power system the terms bus voltage and rms current of line are very important. In case of three phase power system mainly two faults occurs, three phase balance fault and unbalance fault on transmission line of power system, such as line to ground fault, double line to ground fault and double line fault. The transmission line fault analysis helps to select and develop a better for protection purpose[1]. For the protection of transmission line we place the circuit breakers and its rating is depends on triple line fault. The reason behind is that the triple line fault current is very high as compare to other fault current.
simulation in computer, the analysis of transmission line fault can be easily carried out. The main purpose of this paper is to study the general fault type which is Unbalance faults of transmission line in the power system. Also to perform the analysis and obtain the Result of various parameters (voltage, current, power etc.) from simulation on those types of fault Using MATLAB. A new
modeling framework for analysis and simulation of unbalance fault
in power system on IEEE 14 bus system is Procedure includes the frequency information in dynamical models and produces approximate nonlinear Models that are well adopted for analysis and simulation. The transformer model includes Saturation. The parameters have been obtained from practical or experimental measurement.
Conclusion:-
The aforementioned benefits are typically seen to increase transmission lines capacity. Benefits of TCSC are not subject only to newly built TCSC installation but they can also be achieved by upgrading existing series compensation on the thyristors controlled series compensation or only its part, thus considerably extended its influence and usefulness.
IRJET-Review on Power Quality Enhancement in weak Power Grids by Integration ...IRJET Journal
Prathmesh Mayekar, Mahesh Wagh, Nilkanth Shinde "Review on Power Quality Enhancement in weak Power Grids by Integration of Renewable Energy Technologies", International Research Journal of Engineering and Technology (IRJET), Volume2,issue-01 April 2015.e-ISSN:2395-0056, p-ISSN:2395-0072. www.irjet.net
Abstract
During Last decade power quality problems has become more complex at all level of power system. With the increased use of sophisticated electronics, high efficiency variable speed drive, power electronic controllers and also more & more non-linear loads, Power Quality has become an increasing concern to utilities and customers. The modern sensitive, Non-linear and sophisticated load affects the power quality. This paper deals with the issues of low power quality in weak power grids. Initially the various power quality issues are discussed with their definition or occurrence and then finally the solution to mitigate this power quality issues are discussed. The innovative solutions like integration of renewable energy systems along with energy storage to enhance power quality by interfacing with custom power devices are explained in detail. Nearly all sorts of solution for mitigating power quality issue require some sort of DC source for providing active power, which can be supplied by renewable energy source. Also the various energy storage systems are studied.
IRJET- UPQC System for Improved Control MethodIRJET Journal
This document summarizes a research paper on improving the control method for a Unified Power Quality Conditioner (UPQC) system. The UPQC combines a shunt active filter and series active filter to compensate for both current and voltage disturbances. The proposed control method develops a PQ theory-based control for the series active filter and a hysteresis voltage control for the shunt active filter. The UPQC aims to improve power quality under both balanced and distorted load conditions. Key goals of the control schemes are for the shunt filter to absorb current harmonics and reactive power, and for the series filter to regulate voltage at the load terminal.
A High-Performance SPWM Controller for Three-Phase UPS Systems Operating Unde...ijiert bestjournal
The increased use of rectifiers in critical loads employed by the information technologies,and medical and military equipment mandate the design of uninterruptible power supplies (UPS) with high- quality outputs. The highly nonlinear currents drawn especially by high-power single-phase rectifier loads greatly distort the uninterruptible power supplies (UPS) outputs. The distorted uninterruptible power supplies (UPS) voltages cause generation of low dc voltage at the output of the rectifier loads,which causes high current flow,increased power losses,and possibly the malfunction of the critical load or the uninterruptible power supplies (UPS). As a result,different harmonics mitigating techniques have gained a lot of attention. The main objective of this project is to develop simulation of a high-performance Pulse Width Modulation (PWM) technique based AC-DC converter system operating under highly nonlinear loads using MATLAB/SIMULINK. Here,controlled Insulated-gate bipolar transistor (IGBT) based AC-DC converter is used to supply the load instead of Diode or Thyristor Bridge. The pulse width modulation method is quite effective in controlling the root mean square (RMS) magnitude of the AC-DC converter output voltages and shape of input current. This enables automatic harmonic compensation by Rectifier itself.
MITIGATING ELECTRICAL DISTURBANCES WITH HYBRID DISTRIBUTION TRANSFORMERijscmcj
Hybrid transformers (HT) have the advantages of the conventional transformer, the regulatory abilities of
power electronic converters, and reduce the impact of the grid. The impacts of the existing grid are
voltage sag, voltage swell, harmonic distortion, and voltage unbalanced. The power electronic converter
has a controllable advantage such as regulating the voltage and can transfer only a fraction of the power.
The aim of the paper is to augment the conventional power distribution transformer with a partially rated
power electronic module to enhance flexibility and introduce new features to the distribution transformer.
In this paper, the proposed back-to-back converter included an active front rectifier and a modular
multilevel converter (MMC) was simulated by MATLAB/Simulink software. The proposed back-to-back
converter was used at the primary side of the distribution transformer to compensate for the voltage sag
and swell issues. The simulation results were obtained under different conditions such as various supply
voltages and various loads. Hence, the proposed system has the ability to regulate the output voltage
under various conditions with ±10%.
Electrical Engineering: An International Journal (EEIJ)ijccmsjournal
Hybrid transformers (HT) have the advantages of the conventional transformer, the regulatory abilities of
power electronic converters, and reduce the impact of the grid. The impacts of the existing grid are
voltage sag, voltage swell, harmonic distortion, and voltage unbalanced. The power electronic converter
has a controllable advantage such as regulating the voltage and can transfer only a fraction of the power.
The aim of the paper is to augment the conventional power distribution transformer with a partially rated
power electronic module to enhance flexibility and introduce new features to the distribution transformer.
In this paper, the proposed back-to-back converter included an active front rectifier and a modular
multilevel converter (MMC) was simulated by MATLAB/Simulink software. The proposed back-to-back
converter was used at the primary side of the distribution transformer to compensate for the voltage sag
and swell issues. The simulation results were obtained under different conditions such as various supply
voltages and various loads. Hence, the proposed system has the ability to regulate the output voltage
under various conditions with ±10%.
MITIGATING ELECTRICAL DISTURBANCES WITH HYBRID DISTRIBUTION TRANSFORMERijscmcj
Hybrid transformers (HT) have the advantages of the conventional transformer, the regulatory abilities of
power electronic converters, and reduce the impact of the grid. The impacts of the existing grid are
voltage sag, voltage swell, harmonic distortion, and voltage unbalanced. The power electronic converter
has a controllable advantage such as regulating the voltage and can transfer only a fraction of the power.
The aim of the paper is to augment the conventional power distribution transformer with a partially rated
power electronic module to enhance flexibility and introduce new features to the distribution transformer.
In this paper, the proposed back-to-back converter included an active front rectifier and a modular
multilevel converter (MMC) was simulated by MATLAB/Simulink software. The proposed back-to-back
converter was used at the primary side of the distribution transformer to compensate for the voltage sag
and swell issues. The simulation results were obtained under different conditions such as various supply
voltages and various loads. Hence, the proposed system has the ability to regulate the output voltage
under various conditions with ±10%
report of Improvement of the Electric Power Quality Using Series Active and S...Vikram Rawani
The increase of nonlinear loads due to the proliferation of electronic equipment causes power quality in the power system to deteriorate. Harmonic current drawn from a supply by the nonlinear load results in the distortion of the supply voltage waveform at the point of common coupling (PCC) due to the source impedance. Both distorted current and voltage may cause end-user equipment to malfunction, conductors to overheat and may reduce the efficiency and life expectancy of the equipment connected at the PCC.
The peer-reviewed International Journal of Engineering Inventions (IJEI) is started with a mission to encourage contribution to research in Science and Technology. Encourage and motivate researchers in challenging areas of Sciences and Technology.
IRJET- A Comparative Study of Various Filters for Power Quality ImprovementIRJET Journal
This document discusses various filters that can be used to improve power quality by reducing harmonics and correcting power factor. It describes passive filters, shunt active power filters, and series active power filters. Shunt active power filters inject harmonic currents to cancel out load harmonics, while series active power filters generate compensating voltages. Both types of active filters require control schemes to generate the proper compensating signals. Passive filters use tuned filter branches to sink harmonic currents or block harmonic voltages. The document evaluates the compensation characteristics and control methods of different filter topologies to mitigate power quality issues like harmonics and reactive power.
A Review on Optimization Techniques for Power Quality Improvement using DSTAT...ijtsrd
This document summarizes a research paper that proposes using a neural network approach to optimize techniques for improving power quality using a DSTATCOM (Distribution Static Compensator). It begins by introducing common power quality issues like voltage sags, swells, and harmonics. It then discusses different custom power devices used to address these issues, focusing on the DSTATCOM. The paper proposes a control algorithm using a backpropagation neural network to extract reference currents and control the DSTATCOM for reactive power compensation, load balancing, and voltage regulation. Simulation results showed the DSTATCOM was able to satisfactorily compensate for different types of loads using this neural network approach.
This document discusses methods for controlling voltages and reactive power in power system networks using automatic voltage regulators (AVRs) and static var compensators. It provides an overview of these control methods, including AVRs on generators for voltage regulation and static var compensators for reactive power support. The document evaluates the performance of these methods for enhancing voltage control, improving system stability, and minimizing reactive power flows and losses. Key methods discussed are synchronous generator excitation control using AVRs, transmission system voltage control using shunt capacitors and static var compensators.
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.
IRJET- Voltage Stability Improvement and Reactive Power Compensation using ST...IRJET Journal
1) The document discusses improving voltage stability and reactive power compensation in a transmission line using STATCOM (Static Synchronous Compensator) in MATLAB.
2) It simulates a three phase transmission line in MATLAB and observes the voltage drop when an additional load is added.
3) To mitigate this voltage drop, a STATCOM is used to dynamically inject reactive power and regulate the transmission voltage. The MATLAB model and results showing improved voltage stability with STATCOM are presented and analyzed.
Research Inventy : International Journal of Engineering and Scienceinventy
Research Inventy : International Journal of Engineering and Science
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed
This document discusses a study on using a Unified Power Quality Conditioner (UPQC) to improve power quality issues. The UPQC is a device that uses both series and shunt active power filters to compensate for voltage and current related problems simultaneously. The study uses MATLAB simulation to demonstrate how a UPQC model can reduce the total harmonic distortion (THD) in the source voltage, source current, and load voltage caused by nonlinear loads. Control strategies like synchronous reference frame (SRF) theory are applied to the UPQC operation. The document provides background on power quality issues like voltage sag, swell, harmonics, and waveform distortion. It also describes the basic configuration, design, and control methods of the UPQC using S
Power quality improvement by series active power filter- a reviewIRJET Journal
This document summarizes research on using a series active power filter to improve power quality by compensating for voltage distortions. It discusses how power quality issues have increased due to more nonlinear loads. A series active power filter works by injecting a compensating voltage in series with the supply voltage to regulate the voltage and reduce harmonics. The document reviews the configuration of a series active power filter system and its control scheme, which uses a phase-locked loop and reference voltage generation to produce compensating voltages based on supply voltage measurements. It aims to demonstrate how a series active power filter can effectively improve voltage quality for customers by compensating for issues like sags, swells, and harmonics from nonlinear loads.
Power quality enhancement by improving voltage stability using dstatcomeSAT 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
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2. 26 International Journal of Research in Science & Technology
Power Quality Improvement by UPQC based on Voltage Source Converters
neutral currents cause low system efficiency and poor power
factor.
In addition to this, the power system is subjected to various
transients like voltage sags, swells, flickers etc. These
transients would affect the voltage at distribution levels.
Excessive reactive power of loads would increase the
generating capacity of generating stations and increase the
transmission losses in lines. Hence supply of reactive power
at the load ends becomes essential.
Power Quality (PQ) has become an important issue since
many loads at various distribution ends like adjustable speed
drives, process industries, printers; domestic utilities,
computers, microprocessor based equipment etc. have
become intolerant to voltage fluctuations, harmonic content
and interruptions.
Power Quality (PQ) mainly deals with issues like
maintaining a fixed voltage at the Point of Common Coupling
(PCC) for various distribution voltage levels irrespective of
voltage fluctuations, maintaining near unity power factor
power drawn from the supply, blocking of voltage and current
unbalance from passing upwards from various distribution
levels, reduction of voltage and current harmonics in the
system and suppression of excessive supply neutral current.
Conventionally, passive LC filters and fixed compensating
devices with some degree of variation like thyristor switched
capacitors, thyristor switched reactors were employed to
improve the power factor of ac loads. Such devices have the
demerits of fixed compensation, large size, ageing and
resonance. Nowadays equipments using power
semiconductor devices, generally known as Active Power
Filters (APF's), Active Power Line Conditioners (APLC's)
etc. are used for the power quality issues due to their dynamic
and adjustable solutions. Flexible AC Transmission Systems
(FACTS) and Custom Power products like STATCOM
(Static Synchronous Compensator), DVR (Dynamic Voltage
Restorer), etc. deal with the issues related to power quality
using similar control strategies and concepts. Basically, they
are different only in the location in a power system where they
are deployed and the objectives for which they are deployed
[1].
Active Power Filters can be classified, based on converter
type, topology and the number of phases. Converter types are
Current Source Inverter (CSI) with inductive energy storage
or Voltage Source Inverter (VSI) with capacitive energy
storage. The topology can be shunt, series or combination of
both. The third classification is based on the number of
phases, such as single phase systems, three phase systems or
three phase four wire systems.
In this paper, various extraction algorithms for generating
reference signals and various modulation techniques for
generating pulses already developed and published are
discussed. Criterion for selection of dc link capacitor and
interfacing filter design are also discussed.
The Objective of this paper, one such APLC known as
Unified Power Quality Conditioner (UPQC), which can be
used at the PCC for improving power quality, is designed,
simulated using proposed control strategy and the
performance is evaluated for various nonlinear loads [2] [3].
II. POWER QUALITY PROBLEMS
Power quality is very important term that embraces all
aspects associated with amplitude, phase and frequency of the
voltage and current waveform existing in a power circuit. Any
problem manifested in voltage, current or frequency deviation
that results in failure of the customer equipment is known as
power quality problem.
The increasing number of power electronics based
equipment has produced a significant impact on the quality of
electric power supply. The lack of quality power can cause
loss of production, damage of equipment or appliances,
increased power losses, interference with communication
lines and so forth. Therefore, it is obvious to maintain high
standards of power quality [3].
The major types of power quality problems are:
Interruption, Voltage-sag, Voltage-swell, Distortion, and
harmonics.
A. Voltage Sags
Voltage sag or dip represent a voltage fall to 0.1 to 0.9 p.u.
and existing for less than one minute. This is shown in fig 1.
Voltage sag can cause loss of production in automated
process since a voltage sag trip a motor or cause its controller
to malfunction namely microprocessor based control system,
programmable logic controller, adjustable speed drives, that
may lead to a process stoppage, tripping of contractors and
loss of efficiency of electric machine. Impact of long duration
variation is greater than those of short duration variation [4].
Fig. 1 Voltage Sag
B. Voltage Swell
Voltage swell is the rise in voltage of greater than 1.1 p.u.
and exists for less than one minute shown in fig 2.
Swells are usually associated with system fault conditions,
but they are much less common than voltage sags. A swell can
occur due to a single line-to-ground fault on the system which
can result temporary voltage rise on the other unwanted
phases. Swells can also be caused by switching off a large
load or switching on a large capacitor bank. Voltage swells
can put stress on computer and many home appliances. It also
causes tripping of protective circuit of an adjustable speed
drive [5].
Fig. 2 Voltage Swell
C. High Harmonic in Distribution System
It is a sinusoidal component of a periodic wave having a
frequency that is an integral multiple of the fundamental
frequency as shown in fig.3. Harmonics can be considered as
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Volume: 2 | Issue: 1 | January 2015 | ISSN: 2349-0845IJRST
voltages or current present on an electrical system at some
multiple of the fundamental frequency.
Non-linear elements in power system such as power
electronic devices, static power converters, arc discharge
devices, and lesser degree rotating machines create current
distortion. Static Power converters of electrical power are
largest nonlinear loads and are used in industry for a verity of
purposes, such as electrochemical power supplies adjustable
speed drives, and uninterruptible power supplies. These
devices are useful because convert ac to dc, dc to dc, dc to ac,
and ac to ac. Harmonics cause wave from distortion power
system problems such as communication interference,
heating, and solid-state device malfunction can be direct
result of harmonics [4].
Fig. 3 Voltage Harmonics
III. BASIC CONFIGURATION OF UPQC
In recent years, solutions based on flexible ac transmission
systems (FACTS) have appeared. The application of FACTS
concepts in distribution systems has resulted in a new
generation of compensating devices
.
Fig: 4 Basic Configuration of the UPQC
A unified power-quality conditioner (UPQC) is the
extension of the unified power-flow controller (UPFC)
concept at the distribution level. It consists of combined series
and shunt converters for simultaneous compensation of
voltage and current imperfections in a supply feeder.
However, a UPFC only needs to provide balance shunt
and/or series compensation, since a power transmission
system generally operates under a balanced and distortion free
environment. On the other hand, a power distribution system
may contain dc components, distortion, and unbalance both in
voltages and currents. Therefore, a UPQC should operate
under this environment while performing shunt and/or series
compensation [6].
The main purpose of a UPQC is to compensate for supply
voltage power quality issues, such as, sags, swells, unbalance,
flicker, harmonics, and for load current power quality
problems, such as, harmonics, unbalance, reactive current,
and neutral current. Fig.1 shows a single-line representation
of the UPQC system configuration. The key components of
this system are as follows.
1. Two inverters one connected across the load which
acts as a shunt APF and other connected in series
with the line as that of series APF.
2. Shunt coupling inductor LSh is used to Interface the
shunt inverter to the network. It also helps in
smoothing the current wave shape. Sometimes an
isolation transformer is utilized to electrically isolate
the inverter from the network.
3. A common dc link that can be formed by using a
Capacitor or an inductor. In Fig. 1, the dc link is
realized using a capacitor which interconnects the
two inverters and also maintains a constant self
supporting dc bus voltage across it.
4. An LC filter that serves as a passive low-pass filter
(LPF) and helps to eliminate high- frequency
switching ripples on generated inverter output
voltage.
5. Series injection transformer that is used to connect the
series inverter in the network. A suitable turn ratio is
often considered to reduce the current or and voltage
rating of the series inverter.
The integrated controller of the series and shunt APF of the
UPQC to provide the compensating voltage reference VC*
and compensating current reference IC* to be synthesized by
PWM converters [7], [8].
The shunt active power filter of the UPQC can compensate
all undesirable current components, including harmonics,
imbalances due to negative and zero sequence components at
the fundamental frequency. In order to cancel the harmonics
generated by a nonlinear load, the shunt inverter should inject
a current as governed by the following equation:
IC(ωt) = I*L(ωt) - IS(ωt) (1)
Where IC(ωt), I*L(ωt) and IS(ωt) represent the shunt inverter
current, reference load current, and actual source current,
respectively.
The series active power filter of the UPQC can compensate
the supply voltage related problems by injecting voltage in
series with line to achieve distortion free voltage at the load
terminal. The series inverter of the UPQC can be represented
by following equation:
VC(ωt) = V*L(ωt) - VS(ωt) (2)
Where VC (ωt), V*L(ωt) and VS(ωt) represent the series
inverter voltage, reference load voltage, and actual source
voltage, respectively[9] [10].
IV. CONTROL STRATEGIES OF UPQC
A. System Configuration
Basic block diagram of UPQC is shown in Fig 5, where as
the overall control circuit is shown in the Fig 7. The voltage at
PCC may be or may not be distorted depending on the other
non-linear loads connected at PCC. Here we assume the
voltage at PCC is distorted. Two voltage source inverters are
connected back to back, sharing a common dc link. One
inverter is connected parallel with the load. It acts as shunt
APF, helps in compensating load harmonic current as well as
4. 28 International Journal of Research in Science & Technology
Power Quality Improvement by UPQC based on Voltage Source Converters
to maintain dc link voltage at constant level. The second
inverter is connected in series with utility voltage by using
series transformers and helps in maintaining the load voltage
sinusoidal.
Fig 5 Basic Block Diagram of UPQC
B. Reference Generation (Phase Locked Loop)
Reference currents and voltages are generated using Phase
Locked Loop (PLL). The control strategy is based on the
extraction of Unit Vector Templates from the distorted input
supply. These templates will be then equivalent to pure
sinusoidal signal with unity (p.u.) amplitude. The extraction
of unit vector templates is shown in the Fig 6.
The 3-ph distorted input source voltage at PCC contains
fundamental component and distorted component. To get unit
input voltage vectors Uabc, the input voltage is sensed and
multiplied by gain equal to 1/Vm, where Vm is equal to peak
amplitude of fundamental input voltage. These unit input
voltage vectors are taken to phase locked loop (PLL). With
proper phase delay, the unit vector templates are generated.
Ua = Sin (wt)
Ub = Sin (wt-120) (3)
Uc= Sin (wt+120)
Multiplying the peak amplitude of fundamental input voltage
with unit vector templates of equation (3) gives the reference
load voltage signals,
V*
abc = Vm. Uabc (4)
Fig 6 Extraction of Unit Vector Templates and 3-Ph Reference Voltages
In order to have distortion less load voltage, the load
voltage must be equal to these reference signals. The
measured load voltages are compared with reference load
voltage signals. The error generated is then taken to a
hysteresis controller to generate the required gate signals for
series APF.
The unit vector template can be applied for shunt APF to
compensate the harmonic current generated by non-linear
load. The shunt APF is used to compensate for current
harmonics as well as to maintain the dc link voltage at
constant level. To achieve the abovementioned task the dc
link voltage is sensed and compared with the reference dc link
voltage. A PI controller then processes the error. The output
signal from PI controller is multiplied with unit vector
templates of equation (3) giving reference source current
signals. The source current must be equal to this reference
signal. In order to follow this reference current signal, the
3-ph source currents are sensed and compared with reference
current signals. The error generated is then processed by a
hysteresis current controller with suitable band, generating
gating signals for shunt APF.
Fig 7 Overall Control Circuit Configuration of UPQC
C. Modulation Method (Hysteresis Control)
The UPQC uses two back-to-back connected three phase
VSI’s sharing a common dc bus. The hysteresis controller is
used here to control the switching of the both VSI’s.
Hysteresis control law for Series APF:
If (Vact) > (Vref + HB) upper switch of a leg is ON and lower
switch is OFF.
If (Vact) < (Vref - HB) upper switch of a leg is OFF and lower
switch is ON.
Hysteresis control law for Shunt APF:
If (iact) > (iref + HB) upper switch of a leg is ON and lower
switch is OFF.
If (iact) < (iref - HB) upper switch of a leg is OFF and lower
switch is ON.
where HB is the hysteresis band.
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Volume: 2 | Issue: 1 | January 2015 | ISSN: 2349-0845IJRST
V. SIMULATION RESULTS
To verify the operating performance of the proposed
UPQC, a 3-phase electrical system, a PLL extraction circuit
with hysteresis controlled UPQC is simulated using
MATLAB software. The simulation diagram is shown in
figure 8.
Discrete,
Ts = 5e-005 s.
powergui
N
A
B
C
A
B
C
a
b
c
A
B
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a
b
c
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b
c
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a
b
c
A
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B
C
A
B
C
A
B
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A
B
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A
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C
SeriesController Measurements
12
Lt
12
LT
A
B
C
N
LOAD
g
C
E
g
C
E
g
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E
g
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g
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g
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g
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g
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g
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E
s24
s26 s22
s25s23s21s15
s11
s14
s16 s12
s13
A
B
C
a
b
c
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b
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Shunt controller
12
Fig 8 Matlab/Simulink Model
The simulation results are shown in the Fig 9. Both the
series and shunt APF’s are put into the operation from 0.15
seconds time instant, such that both series and shunt APF’s
are operated as UPQC.
Fig 9 Simulation Results (a) Supply Voltage (b) Injected Voltage through
Series Converter and (c) Load Voltage
Fig 10 Simulation Results (a) Supply Current (b) Current at series converter
and (c) Load Current
Fig 10 Simulation Results (a) Active Power and (b) Reactive Power
0 0.05 0.1 0.15 0.2 0.25 0.3
-200
0
200
Selected signal: 15 cycles. FFT window (in red): 2 cycles
Time (s)
0 200 400 600 800 1000
0
10
20
30
40
50
Frequency (Hz)
Fundamental (50Hz) = 183.4 , THD= 52.30%
Mag(%ofFundamental)
Fig 11 THD Analysis without UPQC (52.30%)
0 0.05 0.1 0.15 0.2 0.25 0.3
-200
0
200
Selected signal: 15 cycles. FFT window (in red): 2 cycles
Time (s)
0 200 400 600 800 1000
0
1
2
3
4
5
Frequency (Hz)
Fundamental (50Hz) = 316.2 , THD= 5.66%
Mag(%ofFundamental)
Fig 11 THD Analysis with UPQC (5.66%)
0 0.05 0.1 0.15 0.2 0.25 0.3
-50
0
50
Selected signal: 15 cycles. FFT window (in red): 2 cycles
Time (s)
0 200 400 600 800 1000
0
1
2
3
4
5
6
7
Frequency (Hz)
Fundamental (50Hz) = 19.81 , THD= 7.97%
Mag(%ofFundamental)
Fig 12 THD Analysis of Source Current without UPQC (7.97%)
6. 30 International Journal of Research in Science & Technology
Power Quality Improvement by UPQC based on Voltage Source Converters
0 0.05 0.1 0.15 0.2 0.25 0.3
-50
0
50
Selected signal: 15 cycles. FFT window (in red): 2 cycles
Time (s)
0 200 400 600 800 1000
0
1
2
3
4
Frequency (Hz)
Fundamental (50Hz) = 66.02 , THD= 4.85%
Mag(%ofFundamental)
Fig 13 THD Analysis of Source Current with UPQC (4.85%)
Table 1 Voltage and Current Harmonics (THD’s) of UPQC
Order of
harmonics
Without
UPQC utility
side voltage
With UPQC
utility side
voltage
Without
UPQC
source
Current
With
UPQC
source
Current
3rd
&5th
52.33% 5.66% 7.79% 4.85%
VI. CONCLUSION
Custom power devices like DVR, D-STATCOM, and
UPQC can enhance power quality in the distribution system.
Based on the power quality problem at the load or at the
distribution system, there is a choice to choose particular
custom power device with specific compensation. Unified
Power Quality Conditioner (UPQC) is the combination of
series and shunt APF, which compensates supply voltage and
load current imperfections in the distribution system.
The UPQC considered in this project is a multifunction
power conditioner which can be used to compensate for
various voltage disturbance of the power supply, to correct
any voltage fluctuation and to prevent the harmonic load
current from entering the power system.
A simple control technique based on unit vector templates
generation is proposed for UPQC. Proposed model has been
simulated in MATLAB. The simulation results show that the
input voltage harmonics and current harmonics caused by
non-linear load can be compensated effectively by the
proposed control strategy. The closed loop control schemes of
direct current control, for the proposed UPQC have been
described. A suitable mathematical model of the UPQC has
been developed with PI controller. Simulation results show
that with UPQC THD is minimum for both the voltage and
current.
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