The document describes the use of active power filters to improve power quality by compensating for harmonics and reactive power required by nonlinear loads. It discusses shunt active power filters, which compensate for harmonic currents, and series active power filters, which compensate for voltage harmonics. The key points are:
1) Shunt active power filters inject harmonic currents to cancel out load current harmonics and maintain the DC link voltage. Series active power filters inject a compensating voltage to cancel out supply voltage harmonics.
2) Reference compensation currents/voltages are estimated using techniques like Fast Fourier Transform and p-q theory.
3) Unified Power Quality Conditioners (UPQC) consist of back-to-
This document describes a simulation study of a PI-controlled three-phase shunt active power filter using hysteresis current control. Shunt active power filters can compensate for harmonics and reactive power required by non-linear loads. The filter employs fast Fourier transform to calculate the reference compensation current. Hysteresis current control is used to inject the compensation current into the line. Simulation results show the filter is able to mitigate harmonic distortion, reactive power compensation, and improve power factor, while maintaining total harmonic distortion within IEEE standards.
Enhancement of Power Quality Using the Combination of Thyristor-Controlled Re...IJERD Editor
This paper proposes the combined system of a thyristor – controlled reactor (TCR) and the shunt active filter for harmonic and reactive power compensation. The tuned passive filter and the TCR form a shunt passive filter to compensate the reactive power. The power system harmonics are a menace to electric power system with disastrous consequences. The line current harmonics can cause increase in losses, instability and voltage distortion. Shunt active filters have been used near harmonic producing loads or at the point of common coupling to block the current harmonics. With the diverse application involving reactive power together with harmonic compensation, passive filters are found suitable. The total harmonic distortion and compensation current are carried out in MATLAB using SIMULINK. With the increase in non-linear loads in power system, more and more filters are required. The active filters are designed and analysed to improve the power quality
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.
Implementation of Instantaneous Reactive Power Theory for Current Harmonic Re...IOSR Journals
This document discusses implementing the instantaneous reactive power theory (IRP theory) for current harmonic reduction and reactive power compensation in a three phase four wire power system. The IRP theory defines instantaneous power components in the α-β-0 coordinate system. It can calculate the reference compensating currents required by a shunt active power filter to inject into the network. Simulations show the power filter can reduce current harmonics and reactive power, improving the power factor by making the source current sinusoidal and in phase with the voltage. The IRP theory provides a flexible way to select the undesirable power components for compensation to minimize pollution from nonlinear loads.
Power system harmonics are a menace to electric power system with disastrous consequence. Due to the presence of non linear load, power quality of the system gets affected. To overcome this, shunt active power filter have been used near harmonic producing loads or at the point of common coupling to block current harmonics. The shunt active power filter is designed to minimize harmonics in source current and reactive power in the non linear power supplies which are creating harmonics. In this paper, Instantaneous power of p-q theory is employed to generate the reference currents and PI controller is used to control the dc link voltage. In addition to this, Artificial Intelligence (AI) technique is used to minimize the harmonics produced by nonlinear load. The main objective of this paper is to analyze and compare THD of the source current with PI controller and by artificial neural network based back propagation algorithm. The proposed system is designed with MATLAB/SIMULINK environment.
Shunt active power filters based on diode clamped multilevel inverter and hys...Alexander Decker
This document discusses a shunt active power filter system based on an 11-step diode clamped multilevel inverter and hysteresis band current controller. The system aims to compensate for harmonics in non-linear loads and improve power quality. A two inverter shunt active power filter configuration is proposed to reduce total harmonic distortion and device ratings. Instantaneous reactive power theory is used to generate reference currents, which the hysteresis controller then uses to generate switching signals for the multilevel inverter. Simulation results show the system can achieve 1.8% THD, 0.99 power factor, and compensate 10MW of active and 0.3MVAR of reactive power.
In This paper we present experimental comparative study of feedBack Linearized and Proportional Integral (PI) Controller of the DC bus voltage of three phase shunt Active Power Filter (APF). The FeedBack Linearized and PI controllers are introduced to improve tracking performance characteristics, power quality and minimized consumption of the reactive power. The algorithm used to identify the reference currents is based on the Self Tuning Filter (STF). The firing pulses of the IGBTs inverter are generated using a hysteresis current controller; which is implemented on an analogue card. Finally, the above study, under steady state and transient conditions, is illustrated with signal-flow graphs and corresponding analysis. This study was verified by experimental tests on hardware prototype based on dSPACE-1104. The experimental results show the feasibility and the effectiveness of the designed active filter, associated with Feedback Linearized and PI controllers and are capability in meeting the IEEE 519-1992 recommended harmonic standard limits.
Cascaded Multilevel Inverter Based Active Power Filters: A Survey of ControlsIOSR Journals
This document summarizes several control strategies for cascaded multilevel inverter based active power filters, including:
1. P-q theory with PI controller, which calculates real and reactive power to generate reference currents but has errors when voltages are distorted.
2. Average power method with carrier phase shifted PWM, which gives accurate results even with distorted voltages by using a PLL and calculating average power.
3. Instantaneous real-power theory with triangular-sampling current modulator, which generates reference currents to compensate for harmonics and reactive power in real-time using simple calculations. It maintains the DC bus voltage and works for generic power systems.
This document describes a simulation study of a PI-controlled three-phase shunt active power filter using hysteresis current control. Shunt active power filters can compensate for harmonics and reactive power required by non-linear loads. The filter employs fast Fourier transform to calculate the reference compensation current. Hysteresis current control is used to inject the compensation current into the line. Simulation results show the filter is able to mitigate harmonic distortion, reactive power compensation, and improve power factor, while maintaining total harmonic distortion within IEEE standards.
Enhancement of Power Quality Using the Combination of Thyristor-Controlled Re...IJERD Editor
This paper proposes the combined system of a thyristor – controlled reactor (TCR) and the shunt active filter for harmonic and reactive power compensation. The tuned passive filter and the TCR form a shunt passive filter to compensate the reactive power. The power system harmonics are a menace to electric power system with disastrous consequences. The line current harmonics can cause increase in losses, instability and voltage distortion. Shunt active filters have been used near harmonic producing loads or at the point of common coupling to block the current harmonics. With the diverse application involving reactive power together with harmonic compensation, passive filters are found suitable. The total harmonic distortion and compensation current are carried out in MATLAB using SIMULINK. With the increase in non-linear loads in power system, more and more filters are required. The active filters are designed and analysed to improve the power quality
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.
Implementation of Instantaneous Reactive Power Theory for Current Harmonic Re...IOSR Journals
This document discusses implementing the instantaneous reactive power theory (IRP theory) for current harmonic reduction and reactive power compensation in a three phase four wire power system. The IRP theory defines instantaneous power components in the α-β-0 coordinate system. It can calculate the reference compensating currents required by a shunt active power filter to inject into the network. Simulations show the power filter can reduce current harmonics and reactive power, improving the power factor by making the source current sinusoidal and in phase with the voltage. The IRP theory provides a flexible way to select the undesirable power components for compensation to minimize pollution from nonlinear loads.
Power system harmonics are a menace to electric power system with disastrous consequence. Due to the presence of non linear load, power quality of the system gets affected. To overcome this, shunt active power filter have been used near harmonic producing loads or at the point of common coupling to block current harmonics. The shunt active power filter is designed to minimize harmonics in source current and reactive power in the non linear power supplies which are creating harmonics. In this paper, Instantaneous power of p-q theory is employed to generate the reference currents and PI controller is used to control the dc link voltage. In addition to this, Artificial Intelligence (AI) technique is used to minimize the harmonics produced by nonlinear load. The main objective of this paper is to analyze and compare THD of the source current with PI controller and by artificial neural network based back propagation algorithm. The proposed system is designed with MATLAB/SIMULINK environment.
Shunt active power filters based on diode clamped multilevel inverter and hys...Alexander Decker
This document discusses a shunt active power filter system based on an 11-step diode clamped multilevel inverter and hysteresis band current controller. The system aims to compensate for harmonics in non-linear loads and improve power quality. A two inverter shunt active power filter configuration is proposed to reduce total harmonic distortion and device ratings. Instantaneous reactive power theory is used to generate reference currents, which the hysteresis controller then uses to generate switching signals for the multilevel inverter. Simulation results show the system can achieve 1.8% THD, 0.99 power factor, and compensate 10MW of active and 0.3MVAR of reactive power.
In This paper we present experimental comparative study of feedBack Linearized and Proportional Integral (PI) Controller of the DC bus voltage of three phase shunt Active Power Filter (APF). The FeedBack Linearized and PI controllers are introduced to improve tracking performance characteristics, power quality and minimized consumption of the reactive power. The algorithm used to identify the reference currents is based on the Self Tuning Filter (STF). The firing pulses of the IGBTs inverter are generated using a hysteresis current controller; which is implemented on an analogue card. Finally, the above study, under steady state and transient conditions, is illustrated with signal-flow graphs and corresponding analysis. This study was verified by experimental tests on hardware prototype based on dSPACE-1104. The experimental results show the feasibility and the effectiveness of the designed active filter, associated with Feedback Linearized and PI controllers and are capability in meeting the IEEE 519-1992 recommended harmonic standard limits.
Cascaded Multilevel Inverter Based Active Power Filters: A Survey of ControlsIOSR Journals
This document summarizes several control strategies for cascaded multilevel inverter based active power filters, including:
1. P-q theory with PI controller, which calculates real and reactive power to generate reference currents but has errors when voltages are distorted.
2. Average power method with carrier phase shifted PWM, which gives accurate results even with distorted voltages by using a PLL and calculating average power.
3. Instantaneous real-power theory with triangular-sampling current modulator, which generates reference currents to compensate for harmonics and reactive power in real-time using simple calculations. It maintains the DC bus voltage and works for generic power systems.
This document describes a simulation of a three-phase shunt active power filter using a fuzzy logic controller to compensate for current harmonics from a non-linear load. It discusses how active power filters can mitigate harmonics and reactive power issues. The simulation shows that the fuzzy logic controller is able to keep the source current balanced, sinusoidal and in phase with the voltage after compensation, reducing the total harmonic distortion from 28.61% to 3.85%. The fuzzy logic controller provides an effective control approach without requiring an accurate mathematical model of the system.
T Source Inverter Based Shunt Active Filter with LCL Passive Filter for the 4...IJPEDS-IAES
The inverter topology is being used as an active filter to reduce the
harmonics in the power system. The traditional voltage source or current
source inverters are having the disadvantages of limited output voltage range
hence it may not be able to supply enough compensating currents during
heavy switching surges, Vulnerable to EMI noise and the devices gets
damaged in either open or short circuit conditions and the main switching
device of VSI and CSI are not interchangeable. The active filters are the type
of DC-AC system with wide range of voltage regulation and integration of
energy storages is often required. This cannot be achieved with conventional
inverters and hence the impedance source inverters have been suggested. The
T source inverters are basically impedance source inverters which can be
used as an active filter in the power system. The MATLAB simulation is
done and the results are discussed in this paper for both the types. The
proposed dampening system is fully characterized by LCL based passive
filters and T source inverter based shunt active filter. The disturbances in the
supply voltage and load current due to the non linear loads are observed in
the simulation. The same is studied after connecting the designed hybrid
shunt active filter in the distribution system. The simulation results obtained
from the proposed method proves that it gives comparatively better THD
value.
This document summarizes a study on simulating and evaluating the performance of a unified power quality conditioner (UPQC) using hysteresis current control. A UPQC consists of back-to-back connected shunt and series active power filters to compensate for load harmonics and voltage distortions. The shunt filter regulates DC link voltage and compensates for current harmonics and reactive power, while the series filter compensates for voltage harmonics. Simulation results show the UPQC is able to mitigate harmonics and improve power quality metrics like power factor to within IEEE standards.
Design of Shunt Active Power Filter to eliminate harmonics generated by CFLpaperpublications3
Abstract: The use of non-linear loads; such as TV sets and computer, microwave ovens, multiple low power diode rectifier, fluorescent lamps and electric drives, draw very distorted currents. These non-linear loads lead to generation of current/voltage harmonics and draw reactive power. This paper presents the three-phase shunt active power filter (SAPF) to compensate harmonics generated by non-linear load (compact fluorescent lamp). The instantaneous active and reactive power theory (called p-q theory) is used to design the control of SAPF. The harmonic distortion and the active filter control scheme have been verified by MATLAB simulation.
IRJET- Power Quality Improvement using Active Power FilterIRJET Journal
This document discusses improving power quality using an active power filter. It proposes a novel circuit topology for a three-phase active power filter (APF) that can suppress harmonic currents and provide complete reactive power compensation. The proposed APF uses a two-arm bridge power converter along with filter inductors, reactive power capacitors, and capacitor/resistor filtering. It is shown to have enhanced harmonic compensation capabilities compared to conventional APF topologies. The APF aims to mitigate issues caused by nonlinear loads such as current harmonics, reduced power factor, and voltage distortions on distribution systems.
presentation of Conference On Electrical And Electronic Engineering 2015sager alswed
The designed three phase SAPF based on instantaneous p-q theory was simulated in MATLAB /SIMULINK by using different load conditions i.e. R-L load, suddenly connected R-L load, and additional unbalance R load. Its application was successfully proved and the validity achieved by minimizing the harmonics and improving PF as summarized in Table 2. Consequently, the supply current is almost pure sinusoidal. THD observed was fund to be within the prescribed limits of 5% as recommended by IEEE-519 standard.
Optimize Controlling of Active Filters Controlled by Pi ControllerIRJET Journal
This document discusses the use of an active power filter controlled by a PI controller to minimize harmonics and improve power quality. It begins with an introduction to active power filters and the need to compensate for non-linear loads. It then provides details on the proposed PI control scheme, including the control system block diagram and simulation model. Simulation results show that the PI-controlled active power filter is able to make the source current sinusoidal and reduce total harmonic distortion.
A new fuzzy based control strategy for three phase shunt active power filtersIAEME Publication
This document discusses a new fuzzy-based control strategy for three-phase shunt active power filters. It begins with an abstract that introduces active power filters and describes a current control scheme that does not require a harmonic detector but uses two current sensors on the supply side. A fuzzy controller and vector PI controller are used for effective harmonic compensation to make the supply current sinusoidal. The proposed control scheme improves accuracy and is not affected by harmonic tracking as it does not use a harmonic detector. The rest of the document provides details on the proposed control strategy, including generating reference currents, typical control schemes for active power filters using PI and VPI controllers, and the advantages of the new fuzzy-based control strategy.
Pll based shunt active harmonic filter to compensate multiple non linear loadsIAEME Publication
This document summarizes a research paper on a shunt active power filter used to compensate for multiple non-linear loads. It uses a phase locked loop (PLL) to generate a reference current signal that is in phase with the source voltage. A hysteresis controller compares the reference current to the measured compensation currents to produce switching signals for an IGBT inverter. Simulation results show the filter can compensate for current harmonics from diode rectifier loads and reduce total harmonic distortion. The proposed filter uses PLL and hysteresis control to estimate the reference current and control the inverter to inject compensation currents.
IRJET- A Review on Power Quality Improvement using Shunt Active Filter with M...IRJET Journal
This document reviews the use of shunt active filters with multilevel inverters to improve power quality by eliminating current harmonics and providing reactive power compensation. It summarizes several research papers on different control techniques used for shunt active filters, such as indirect current control, instantaneous reactive power theory, synchronous reference frame control, and peak detection methods. The conclusion is that shunt active filters can effectively compensate for harmonics, reactive power, and load unbalances to improve power quality and make the source current sinusoidal.
This document discusses using an active power filter (APF) to compensate for power quality issues caused by linear and non-linear loads. It analyzes system performance with and without an APF for different load types. For a linear load without an APF, voltage sag and 2.96% total harmonic distortion are observed. With an APF, voltage sag is eliminated and distortion is reduced to 1.70%. For a non-linear load without an APF, voltage is highly distorted with harmonics. When an APF is added, it monitors the load current and adapts to changes in harmonics to improve power quality. The APF provides a solution for problems like harmonics, reactive power compensation, and voltage regulation
Distribution Static Synchronous Compensator (DSTATCOM) is a shunt compensating device which is used
to improve current profile by exchanging of reactive power with unbalanced and nonlinear load. DSTATCOM is a
shunt compensating device used for power quality improvement in distribution systems. Relevant solutions are
applied for harmonics, fluctuation of voltage, voltage deviation, unbalance of three phase voltage and current and
frequency deviation. Different controlling schemes such as Phase Control Method (PCM), Fryze Power Theory
(FPT), Synchronous Reference Frame Theory (SRFT) and Instantaneous Reactive Power Theory (IRPT) are used
for reactive power compensation with the help of Voltage source Inverter (VSI). In this project we are going to
balance the source current using different control schemes. The results of different source currents are compared
with a different control schemes in terms of active and reactive power and in terms of Total Harmonic Distortion
(THD) for nonlinear load using Fryze Power Theory (FPT) and Instantaneous Reactive Power Theory (IRPT).
Reference currents are generated by the different control schemes have been dynamically traced in a hysteresis
current controller. The performance of DSTATCOM for different control schemes is validated for load balancing
and harmonic elimination by using simulation models in MATLAB/SIMULINK
Study and Estimation of Energy Transfer to the Active DC-Link Capacitor Due t...Premier Publishers
This document discusses the estimation of energy transfer to an active DC-link capacitor in an adjustable speed drive system due to harmonic currents. It presents a methodology to calculate the amount of energy stored in the active capacitor when the ripple energy is positive by using simulation and analytical methods. The active DC-link capacitor compensation circuit aims to mitigate inter-harmonics by transferring energy to the capacitor during positive ripple cycles and feeding energy back to the DC link during negative cycles. Simulation results validate the analytical formulae used to determine the instantaneous voltage and current values in the capacitor and inductor respectively during the energy transfer process.
A NOVEL TCHNOLOGY FOR HARMONICS AND UNBALANCE COMPENSATION IN ELECTRIC TRACTI...ijiert bestjournal
Power quality problems in power systems have been i mproved due to nonlinear loads. To compensate these problems Direct Power Compensator was proposed in this paper. A Direct Power Compensator (DPC) is proposed in this paper to elim inate the harmonic currents,compensate power factor and voltage unbalance problems created by th e nonlinear loads present in three phase systems. A DPC contains back to back converter by sharing th e same dc link power and v/v transformer to provide a voltage balance in transmission line. Hys teresis harmonic current regulator is used to produce pulse for back to back converter. A control ler maintains the dc-link voltage and compensates the power factor,harmonic currents. A comparative analysis for traction system with and without DPC was performed using MATLAB Simulink . Simulation results show the controller advantages and the applicability of the proposed me thod in railway systems.
The document describes the design of a shunt hybrid active power filter (SHAPF) to reduce harmonics on the AC side due to non-linear loads. A SHAPF consists of both an active filter and a passive filter connected in parallel. The active filter uses an instantaneous reactive power theory-based control strategy to calculate compensating currents, while the passive filter includes a tuned RLC circuit to filter specific harmonics. Simulation results using MATLAB Simulink show the SHAPF reduces the total harmonic distortion of the source current from 30.35% to 3.25%, outperforming passive and active filters alone. The control strategy effectively reduces harmonics through feedback compensation provided by the hybrid filter configuration.
This paper presents a grid-connected photovoltaic system (PV) used as a shunt active power filter (SAPF) to provide the power factor correction, harmonic elimination, reactive power compensation and to simultaneously supply power from a PV system to the utility. A direct power control (DPC) method is used for controlling the system to feed the photovoltaic energy in synchronization with grid and provide power quality improvement. The PI parameters of DC-link voltage controller are tuned using the Particle Swarm Optimization (PSO) algorithm without the need for an exact mathematical model of system. This PI-PSO controller gives better results for robustness, harmonic minimization and reduces the overshoot and undershoots of PI controller. The overall control of system is tested in Matlab/Simulink environment. Then, the simulations results demonstrate the robustness and feasibility of proposed method.
This document summarizes a research paper on simulating and investigating the performance of a series active power filter using hysteresis current control.
The paper presents the simulation of a hysteresis current controlled, three-phase series active power filter to improve power quality by compensating for harmonics and reactive power required by a non-linear load. The series active filter employs a simple method for calculating the reference compensation voltage based on p-q theory. The results show the active filter maintains total harmonic distortion well within IEEE standards, providing satisfactory mitigation of harmonics, reactive power compensation, and power factor improvement.
This document describes a simulation of a three-phase shunt active power filter using a fuzzy logic controller to compensate for current harmonics from a non-linear load. It discusses how active power filters can mitigate harmonics and reactive power issues. The simulation shows that the fuzzy logic controller is able to keep the source current balanced, sinusoidal and in phase with the voltage after compensation, reducing the total harmonic distortion from 28.61% to 3.85%. The fuzzy logic controller provides an effective control approach without requiring an accurate mathematical model of the system.
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 System Harmonic Compensation Using Shunt Active Power FilterIJERA Editor
This paper shows the method of improving the power quality using shunt active power filter. The proposedtopic comprises of PI controller, filter hysteresis current control loop, dc link capacitor. The switching signal generation for filter is fromhysteresis current controller techniques. With the all these element shunt active power filter reduce the total harmonic distortion. Thispaper represents the simulation and analysis of the using three phase three wire system active filter to compensate harmonics .Theproposed shunt active filter model uses balanced non-linear load. This paper successfully lowers the THD within IEEE norms and satisfactorily works to compensatecurrent harmonics.
This document presents a simulation study of a hysteresis current controlled series active power filter to improve power quality by compensating for harmonics and reactive power from a non-linear load. The series active filter uses a simple method to calculate the reference compensation voltage based on p-q theory. Simulation results show the active filter maintains total harmonic distortion well within IEEE standards, effectively mitigating harmonic distortion, compensating reactive power, and improving the power factor.
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
This document describes a simulation of a three-phase shunt active power filter using a fuzzy logic controller to compensate for current harmonics from a non-linear load. It discusses how active power filters can mitigate harmonics and reactive power issues. The simulation shows that the fuzzy logic controller is able to keep the source current balanced, sinusoidal and in phase with the voltage after compensation, reducing the total harmonic distortion from 28.61% to 3.85%. The fuzzy logic controller provides an effective control approach without requiring an accurate mathematical model of the system.
T Source Inverter Based Shunt Active Filter with LCL Passive Filter for the 4...IJPEDS-IAES
The inverter topology is being used as an active filter to reduce the
harmonics in the power system. The traditional voltage source or current
source inverters are having the disadvantages of limited output voltage range
hence it may not be able to supply enough compensating currents during
heavy switching surges, Vulnerable to EMI noise and the devices gets
damaged in either open or short circuit conditions and the main switching
device of VSI and CSI are not interchangeable. The active filters are the type
of DC-AC system with wide range of voltage regulation and integration of
energy storages is often required. This cannot be achieved with conventional
inverters and hence the impedance source inverters have been suggested. The
T source inverters are basically impedance source inverters which can be
used as an active filter in the power system. The MATLAB simulation is
done and the results are discussed in this paper for both the types. The
proposed dampening system is fully characterized by LCL based passive
filters and T source inverter based shunt active filter. The disturbances in the
supply voltage and load current due to the non linear loads are observed in
the simulation. The same is studied after connecting the designed hybrid
shunt active filter in the distribution system. The simulation results obtained
from the proposed method proves that it gives comparatively better THD
value.
This document summarizes a study on simulating and evaluating the performance of a unified power quality conditioner (UPQC) using hysteresis current control. A UPQC consists of back-to-back connected shunt and series active power filters to compensate for load harmonics and voltage distortions. The shunt filter regulates DC link voltage and compensates for current harmonics and reactive power, while the series filter compensates for voltage harmonics. Simulation results show the UPQC is able to mitigate harmonics and improve power quality metrics like power factor to within IEEE standards.
Design of Shunt Active Power Filter to eliminate harmonics generated by CFLpaperpublications3
Abstract: The use of non-linear loads; such as TV sets and computer, microwave ovens, multiple low power diode rectifier, fluorescent lamps and electric drives, draw very distorted currents. These non-linear loads lead to generation of current/voltage harmonics and draw reactive power. This paper presents the three-phase shunt active power filter (SAPF) to compensate harmonics generated by non-linear load (compact fluorescent lamp). The instantaneous active and reactive power theory (called p-q theory) is used to design the control of SAPF. The harmonic distortion and the active filter control scheme have been verified by MATLAB simulation.
IRJET- Power Quality Improvement using Active Power FilterIRJET Journal
This document discusses improving power quality using an active power filter. It proposes a novel circuit topology for a three-phase active power filter (APF) that can suppress harmonic currents and provide complete reactive power compensation. The proposed APF uses a two-arm bridge power converter along with filter inductors, reactive power capacitors, and capacitor/resistor filtering. It is shown to have enhanced harmonic compensation capabilities compared to conventional APF topologies. The APF aims to mitigate issues caused by nonlinear loads such as current harmonics, reduced power factor, and voltage distortions on distribution systems.
presentation of Conference On Electrical And Electronic Engineering 2015sager alswed
The designed three phase SAPF based on instantaneous p-q theory was simulated in MATLAB /SIMULINK by using different load conditions i.e. R-L load, suddenly connected R-L load, and additional unbalance R load. Its application was successfully proved and the validity achieved by minimizing the harmonics and improving PF as summarized in Table 2. Consequently, the supply current is almost pure sinusoidal. THD observed was fund to be within the prescribed limits of 5% as recommended by IEEE-519 standard.
Optimize Controlling of Active Filters Controlled by Pi ControllerIRJET Journal
This document discusses the use of an active power filter controlled by a PI controller to minimize harmonics and improve power quality. It begins with an introduction to active power filters and the need to compensate for non-linear loads. It then provides details on the proposed PI control scheme, including the control system block diagram and simulation model. Simulation results show that the PI-controlled active power filter is able to make the source current sinusoidal and reduce total harmonic distortion.
A new fuzzy based control strategy for three phase shunt active power filtersIAEME Publication
This document discusses a new fuzzy-based control strategy for three-phase shunt active power filters. It begins with an abstract that introduces active power filters and describes a current control scheme that does not require a harmonic detector but uses two current sensors on the supply side. A fuzzy controller and vector PI controller are used for effective harmonic compensation to make the supply current sinusoidal. The proposed control scheme improves accuracy and is not affected by harmonic tracking as it does not use a harmonic detector. The rest of the document provides details on the proposed control strategy, including generating reference currents, typical control schemes for active power filters using PI and VPI controllers, and the advantages of the new fuzzy-based control strategy.
Pll based shunt active harmonic filter to compensate multiple non linear loadsIAEME Publication
This document summarizes a research paper on a shunt active power filter used to compensate for multiple non-linear loads. It uses a phase locked loop (PLL) to generate a reference current signal that is in phase with the source voltage. A hysteresis controller compares the reference current to the measured compensation currents to produce switching signals for an IGBT inverter. Simulation results show the filter can compensate for current harmonics from diode rectifier loads and reduce total harmonic distortion. The proposed filter uses PLL and hysteresis control to estimate the reference current and control the inverter to inject compensation currents.
IRJET- A Review on Power Quality Improvement using Shunt Active Filter with M...IRJET Journal
This document reviews the use of shunt active filters with multilevel inverters to improve power quality by eliminating current harmonics and providing reactive power compensation. It summarizes several research papers on different control techniques used for shunt active filters, such as indirect current control, instantaneous reactive power theory, synchronous reference frame control, and peak detection methods. The conclusion is that shunt active filters can effectively compensate for harmonics, reactive power, and load unbalances to improve power quality and make the source current sinusoidal.
This document discusses using an active power filter (APF) to compensate for power quality issues caused by linear and non-linear loads. It analyzes system performance with and without an APF for different load types. For a linear load without an APF, voltage sag and 2.96% total harmonic distortion are observed. With an APF, voltage sag is eliminated and distortion is reduced to 1.70%. For a non-linear load without an APF, voltage is highly distorted with harmonics. When an APF is added, it monitors the load current and adapts to changes in harmonics to improve power quality. The APF provides a solution for problems like harmonics, reactive power compensation, and voltage regulation
Distribution Static Synchronous Compensator (DSTATCOM) is a shunt compensating device which is used
to improve current profile by exchanging of reactive power with unbalanced and nonlinear load. DSTATCOM is a
shunt compensating device used for power quality improvement in distribution systems. Relevant solutions are
applied for harmonics, fluctuation of voltage, voltage deviation, unbalance of three phase voltage and current and
frequency deviation. Different controlling schemes such as Phase Control Method (PCM), Fryze Power Theory
(FPT), Synchronous Reference Frame Theory (SRFT) and Instantaneous Reactive Power Theory (IRPT) are used
for reactive power compensation with the help of Voltage source Inverter (VSI). In this project we are going to
balance the source current using different control schemes. The results of different source currents are compared
with a different control schemes in terms of active and reactive power and in terms of Total Harmonic Distortion
(THD) for nonlinear load using Fryze Power Theory (FPT) and Instantaneous Reactive Power Theory (IRPT).
Reference currents are generated by the different control schemes have been dynamically traced in a hysteresis
current controller. The performance of DSTATCOM for different control schemes is validated for load balancing
and harmonic elimination by using simulation models in MATLAB/SIMULINK
Study and Estimation of Energy Transfer to the Active DC-Link Capacitor Due t...Premier Publishers
This document discusses the estimation of energy transfer to an active DC-link capacitor in an adjustable speed drive system due to harmonic currents. It presents a methodology to calculate the amount of energy stored in the active capacitor when the ripple energy is positive by using simulation and analytical methods. The active DC-link capacitor compensation circuit aims to mitigate inter-harmonics by transferring energy to the capacitor during positive ripple cycles and feeding energy back to the DC link during negative cycles. Simulation results validate the analytical formulae used to determine the instantaneous voltage and current values in the capacitor and inductor respectively during the energy transfer process.
A NOVEL TCHNOLOGY FOR HARMONICS AND UNBALANCE COMPENSATION IN ELECTRIC TRACTI...ijiert bestjournal
Power quality problems in power systems have been i mproved due to nonlinear loads. To compensate these problems Direct Power Compensator was proposed in this paper. A Direct Power Compensator (DPC) is proposed in this paper to elim inate the harmonic currents,compensate power factor and voltage unbalance problems created by th e nonlinear loads present in three phase systems. A DPC contains back to back converter by sharing th e same dc link power and v/v transformer to provide a voltage balance in transmission line. Hys teresis harmonic current regulator is used to produce pulse for back to back converter. A control ler maintains the dc-link voltage and compensates the power factor,harmonic currents. A comparative analysis for traction system with and without DPC was performed using MATLAB Simulink . Simulation results show the controller advantages and the applicability of the proposed me thod in railway systems.
The document describes the design of a shunt hybrid active power filter (SHAPF) to reduce harmonics on the AC side due to non-linear loads. A SHAPF consists of both an active filter and a passive filter connected in parallel. The active filter uses an instantaneous reactive power theory-based control strategy to calculate compensating currents, while the passive filter includes a tuned RLC circuit to filter specific harmonics. Simulation results using MATLAB Simulink show the SHAPF reduces the total harmonic distortion of the source current from 30.35% to 3.25%, outperforming passive and active filters alone. The control strategy effectively reduces harmonics through feedback compensation provided by the hybrid filter configuration.
This paper presents a grid-connected photovoltaic system (PV) used as a shunt active power filter (SAPF) to provide the power factor correction, harmonic elimination, reactive power compensation and to simultaneously supply power from a PV system to the utility. A direct power control (DPC) method is used for controlling the system to feed the photovoltaic energy in synchronization with grid and provide power quality improvement. The PI parameters of DC-link voltage controller are tuned using the Particle Swarm Optimization (PSO) algorithm without the need for an exact mathematical model of system. This PI-PSO controller gives better results for robustness, harmonic minimization and reduces the overshoot and undershoots of PI controller. The overall control of system is tested in Matlab/Simulink environment. Then, the simulations results demonstrate the robustness and feasibility of proposed method.
This document summarizes a research paper on simulating and investigating the performance of a series active power filter using hysteresis current control.
The paper presents the simulation of a hysteresis current controlled, three-phase series active power filter to improve power quality by compensating for harmonics and reactive power required by a non-linear load. The series active filter employs a simple method for calculating the reference compensation voltage based on p-q theory. The results show the active filter maintains total harmonic distortion well within IEEE standards, providing satisfactory mitigation of harmonics, reactive power compensation, and power factor improvement.
This document describes a simulation of a three-phase shunt active power filter using a fuzzy logic controller to compensate for current harmonics from a non-linear load. It discusses how active power filters can mitigate harmonics and reactive power issues. The simulation shows that the fuzzy logic controller is able to keep the source current balanced, sinusoidal and in phase with the voltage after compensation, reducing the total harmonic distortion from 28.61% to 3.85%. The fuzzy logic controller provides an effective control approach without requiring an accurate mathematical model of the system.
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 System Harmonic Compensation Using Shunt Active Power FilterIJERA Editor
This paper shows the method of improving the power quality using shunt active power filter. The proposedtopic comprises of PI controller, filter hysteresis current control loop, dc link capacitor. The switching signal generation for filter is fromhysteresis current controller techniques. With the all these element shunt active power filter reduce the total harmonic distortion. Thispaper represents the simulation and analysis of the using three phase three wire system active filter to compensate harmonics .Theproposed shunt active filter model uses balanced non-linear load. This paper successfully lowers the THD within IEEE norms and satisfactorily works to compensatecurrent harmonics.
This document presents a simulation study of a hysteresis current controlled series active power filter to improve power quality by compensating for harmonics and reactive power from a non-linear load. The series active filter uses a simple method to calculate the reference compensation voltage based on p-q theory. Simulation results show the active filter maintains total harmonic distortion well within IEEE standards, effectively mitigating harmonic distortion, compensating reactive power, and improving the power factor.
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
HYBRID ACTIVE POWER FILTER FOR EFFECTIVE COMPENSATION WITH CONTROL SCHEMEBlossoms Anjali
This document summarizes a research paper on a hybrid active power filter with a control scheme to compensate industrial power supplies. The hybrid active power filter combines a passive filter with an active power filter to compensate for non-linear loads. It can improve power factor and eliminate lower harmonic currents simultaneously. The control scheme uses a microcontroller to calculate the compensating current needed from the active filter based on measurements of the load and line currents. Experimental results showed the hybrid active power filter provided better compensation of harmonics compared to just a passive filter. It allowed the input current, voltage, and compensated output current to be closer to sinusoidal waveforms.
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This document discusses the implementation of instantaneous reactive power theory (IRP theory) for current harmonic reduction and reactive power compensation in three phase four wire power systems. IRP theory is used to calculate reference compensating currents that are injected by a shunt active power filter (SAPF) to compensate for non-linear and reactive loads. Clarke's transformation is used to convert voltages and currents to the α-β-0 reference frame for IRP calculations. Hysteresis current control with a constant switching frequency is used to generate PWM signals to control the SAPF inverter. Simulations show the SAPF reducing current harmonics and reactive power, improving the power factor by making the source current sinusoidal and in phase with
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.
Shunt active power filters based on diode clamped multilevel inverter and hys...Alexander Decker
This document summarizes a research paper on a shunt active power filter system based on an 11-step diode clamped multilevel inverter and hysteresis band current control. The system aims to compensate for harmonics in current drawn by non-linear loads and improve the source power factor. It uses instantaneous reactive power theory to generate reference currents and the hysteresis controller provides switching signals for the multilevel inverter. Simulation results showed the system achieved 1.8% total harmonic distortion, 0.99 power factor, compensating 10MW of active power and 0.3MVAR of reactive power.
Advanced Techniques in Harmonic Suppression via Active Power Filter: A ReviewIJPEDS-IAES
This paper intends to present the recent development of artificial intelligence
(AI) applications in active power filter (APF). As a result of the development
in power electronic technology, (APF) continues to attract ample attention.
Compared with the traditional reactive LC filter, active power filter is
considered to be more effective in compensating harmonic current generated
by nonlinear loads. APF, can correct the power quality and improve the
reliability and stability on power utility. A brief explanation of some
important areas in AI and a comprehensive survey of the literature along the
main categories of AI is presented to introduce the readers into the wideranging
topics that AI encompasses. Plenty of relevant literatures have been
selected in the review, mostly emphasized on better accuracy, robustness,
efficiency, stability and tracking ability of the system.
Comparative Analysis of Power Quality Enhancement of Distribution System usin...IRJET Journal
This document presents a comparative analysis of using a Unified Power Quality Conditioner (UPQC) to improve power quality in a 16-bus distribution system. A UPQC combines series and shunt active power filters to mitigate both voltage and current-based power quality issues. The document describes the components and control strategies of a UPQC. It then models a UPQC connected to the 16-bus system and compares the performance of using different controller types for the UPQC: proportional-integral (PI) controller, neural network, and adaptive neuro-fuzzy inference system (ANFIS). The modeling results show the effectiveness of a UPQC in enhancing power quality by reducing issues like voltage sag, harmonics, and interruptions.
This document presents a novel control strategy for shunt active filters that considers the presence of harmonics in both the system voltage and load current. It compares different methods for estimating the reference compensating current, including notch filtering, instantaneous reactive power theory, synchronous reference frame, fast Fourier transforms, and synthetic fundamental subtraction. Simulation results show that the fast Fourier transform method provides good steady state and transient response for active filters operating under unbalanced system voltages. It can effectively compensate harmonics under these conditions by treating each phase individually. The total harmonic distortion of the source current is reduced below 5% using this method, meeting IEEE standards.
Decomposition of current through active power filter for compensating harmoni...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
The Shunt Active Power Filter to Compensate Reactive Power and Harmonics with...ijtsrd
In this paper is to study the denomination Power quality and large refers to maintaining a proximal sinusoidal power distribution bus voltage at rated magnitude and frequency. This is mainly affected by the generation of harmonics. Even though electronic and non-linear devices are flexible, economical and energy efficient, they may degrade power quality by creating harmonic currents and consuming excessive reactive power. This paper shows the method of improving the power quality using shunt active power filter with proposed optimized PI. The proposed topic comprises of PI controller, filter hysteresis current control loop, dc link capacitor. The switching signal generation for filter is from hysteresis current controller techniques. With the all these element shunt active power filter reduce the total harmonic distortion. Its source current, compensating current and THD values are studied, then PI control strategy is applied then the differences in THD are compared. The PI feedback compensation design starts with the small signal system' transfer function. Then an optimum constant of PI for a Shunt-APF is proposed and implemented to enhance its response to compensation of harmonics of linear and non-linear loads. The obtained results have demonstrated the ability to compensate the current harmonics effectively under distorted source conditions. The fluctuation in the dc bus voltage of the filter depends on the compensation speed of the outer loop that regulates the dc bus voltage. The proposed shunt active filter model uses balanced linear and non-linear load works successfully lowers the THD within IEEE norms and satisfactorily works to compensate current harmonics. The model is made in MATLAB SIMULINK and successfully reduces the harmonic in the source current. Mr. Amit Kumar Rajan | Dr. E Vijay Kumar"The Shunt Active Power Filter to Compensate Reactive Power and Harmonics with optimized PI controller in a 3 Phase 3 Wire Distribution System" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-5 , August 2018, URL: http://www.ijtsrd.com/papers/ijtsrd18196.pdf http://www.ijtsrd.com/engineering/electrical-engineering/18196/the-shunt-active-power-filter-to-compensate-reactive-power-and-harmonics-with-optimized-pi-controller-in-a-3-phase-3-wire-distribution-system/mr-amit-kumar-rajan
IJERD (www.ijerd.com) International Journal of Engineering Research and Devel...IJERD Editor
This document compares two types of current control techniques - direct and indirect - used for a shunt active power filter to compensate for current harmonics from non-linear loads. It also develops a novel fuzzy logic controller to replace the conventional PI controller. The direct method senses both load and filter currents while the indirect method only senses the source current. Simulations show the performance of both methods using PI and fuzzy logic controllers under steady state and transient conditions. The fuzzy logic controller has advantages over PI controllers by not requiring an accurate mathematical model and being more robust.
Mitigation Unbalance Nonlinear Loads and Dissimilar Line Currents Using Shunt...INFOGAIN PUBLICATION
This document presents a new control method for a shunt active power filter (SAPF) to compensate for unbalanced nonlinear loads and dissimilar line currents. The proposed control method uses both dq-theory and instantaneous p-q power theory to calculate reference currents. Fuzzy logic control is also used to optimize the SAPF performance. Simulation results show the controller is effective at mitigating harmonic distortion, compensating load asymmetry, and eliminating negative and zero sequence currents. The total harmonic distortion of the line currents is reduced from 29.8% to 4.1% with this control approach.
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
Power Quality Improvement using Shunt Active Power Filterijtsrd
Nowadays, usage of non linear loads in power system is increasing. For example, UPS, inverters, converters, etc. These loads make the supply current non sinusoidal and distorted form, which is called harmonics. At this time Active power filters have been developed to improve power quality. In this Paper, a Shunt Active Power Filter SAPF control scheme has proposed to eliminate the current harmonics and improve the power quality. The shunt active power filter controlled by using the different controllers such as PI, PID, Fuzzy logic, Pq Theory and hysteresis controller . In our proposed system, PI controller is used to reduce the harmonics current using the shunt active power filter. And both current THD results are compared, with and without use of filter and then shown how filters can reduce THD and is most suitable to control the shunt active power filter in term of total harmonic reduction THD . MATLAB SIMULINK power system toolbox is used to simulate the proposed system. Ankita Upadhyay | Padmesh Singh "Power Quality Improvement using Shunt Active Power Filter" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-3 , April 2020, URL: https://www.ijtsrd.com/papers/ijtsrd30463.pdf Paper Url :https://www.ijtsrd.com/engineering/electrical-engineering/30463/power-quality-improvement-using-shunt-active-power-filter/ankita-upadhyay
This paper presents the control for Shunt Active Power (SAPF) filter in photovoltaic (PV) systems connected to the grid. The proposed configuration of the system consists of a photovoltaic array that connected to the grid through the three-phase inverter topology that also serves as an active filter. Photovoltaic is coupled in parallel with the direct curret (DC) side of the active filter. With this configuration, can be obtained three advantages, namely the elimination of harmonic currents caused by nonlinear load, reactive power injection, and injection of active power generated photovoltaic. The p-q Theory is used to calculate the harmonic reference current to be used to control the active filter coupled fotovoltaic in generating anti-harmonic currents. The results show that system can reduce harmonic distortion from THD 27.22% to be THD 1.05%, whereas when the active power from photovoltaic injected, the THD become 2.01%. Power sharing can also be seen from this study.
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3) The unified power quality conditioner is introduced, which uses both series and shunt active filters to improve both voltage and current quality by controlling series injected voltage and shunt injected current.
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Enhancement of Quality in Power Systems With Active Power Filters
1. IOSR Journal of Engineering (IOSRJEN) www.iosrjen.org
ISSN (e): 2250-3021, ISSN (p): 2278-8719
Vol. 04, Issue 05 (May. 2014), ||V6|| PP 23-32
International organization of Scientific Research 23 | P a g e
Enhancement of Quality in Power Systems With Active Power
Filters
Vikash Anand1
, Dr. S. K. Srivastava2
1
PhD Student, Electrical Engineering, NIT-Patna, Bihar, India
2
Associate Professor, Electrical Engineering, MMMTU-Gorakhpur, Uttar Pradesh, India
Abstract: - The study of hysteresis current controlled three phase active power filters to improve power quality
by compensating harmonics and reactive power required by a non-linear load is presented. The shunt active
filter employs a simple method for the reference compensation current based on Fast Fourier Transform. The
series active filter employs a simple method for the reference compensation voltage based on p-q theory. UPQC
consists of back to back connected series and shunt active filters, and is modeled with reference to a
synchronously rotating d-q-o reference axes. The shunt active power filter compensates the source current
harmonics and also it maintains the dc link voltage unchanged in steady state, while the series active power filter
compensates the load voltage harmonics. Classic filters may not have satisfactory performance in fast varying
conditions. But auto tuned active power filters give better results for harmonics minimization, reactive power
compensation and power factor improvement. This paper has proposed an auto tuned active filter, which
maintains the THD well within the IEEE-519 standards.
Key Words: Power system, Active power filters, PI Controller, Hysteresis Current Pulse Width Modulation.
I. INTRODUCTION
The present power distribution system is usually configured as a three-phase three-wire or four-wire
structure featuring a power-limit voltage source with significant source impedance, and an aggregation of
various types of loads. Ideally, the system should provide a balanced and pure sinusoidal three-phase voltage of
constant amplitude to the loads; and the loads should draw a current from the line with unity power factor, zero
harmonics, and balanced phases. To four-wire systems, no excessive neutral current should exist. As a result, the
maximum power capacity and efficiency of the energy delivery are achieved, minimum perturbation to other
appliances is ensured, and safe operation is warranted. However, with a fast increasing number of applications
of industry electronics connected to the distribution systems today, including nonlinear, switching, reactive,
single-phase and unbalanced three-phase load, a complex problem of power quality evolved characterized by the
voltage and current harmonics, unbalances, low power factor. [1]
In recent years active methods for power quality control have become more attractive compared with
passive ones due to their fast response, smaller size, and higher performance. For example, Static VAR
Compensator (SVC) have been reported to improve the power factor; Power Factor Corrector (PFC) and Active
Power Filters (APF) have the ability of current harmonics suppression and power factor correction; some active
circuits were developed to compensate unbalanced currents as well as limit the neutral current. In general,
parallel-connected converters have the ability to improve the current quality while the series-connected
regulators inserted between the load and the supply, improve the voltage quality. For voltage and current quality
control, both series and shunt converters are necessary, which is known as Unified Power Quality Conditioner
(UPQC) and have been analyzed in this thesis. UPQC was presented during 1998. Such solution can compensate
for different power quality phenomena, such as: sags, swells, voltage imbalance, flicker, harmonics and reactive
currents. [7]
There are several current control strategies proposed in the literature, namely, PI control, Average
Current Mode Control (ACMC), Sliding Mode Control (SMC) and hysteresis control. Among the various
current control techniques, hysteresis control is the most popular one for active power filter applications.
Hysteresis current control is a method of controlling a voltage source inverter so that the output current is
generated which follows a reference current waveform. [2, 11]
This paper basically deals with the modeling and design of active power filters for compensation of
harmonics and reactive power. Designs of different parameters like power circuit, thyristor controlled capacitor
banks; series active filter, shunt active filter, UPQC are discussed.
II. SHUNT ACTIVE POWER FILTER (SHUNT APF)
The shunt active power filter, with a self controlled dc bus, has a topology similar to that of a static
compensator (STATCOM) used for reactive power compensation in power transmission systems. Shunt active
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power filters compensate load current harmonics by injecting equal but opposite harmonic compensating
current. In this case the shunt active power filter operates as a current source injecting the harmonic components
generated by the load but phase shifted by 180o
. Fig.1 shows the three leg topology of shunt active filter. Fig.2
shows how active power filter works to compensate the load harmonic currents and Fig.3 shows the connection
of a shunt active power filter. [2, 7, 9]
Fig.1 Three leg topology of shunt active power filter
IF
IS IL
Shunt
Active
Filter
Non-linear
Load
Sinusoidal
Source
Source
Current
Load
Current
Filter
Current
Fig.2 Filter current IF generated to compensate load current harmonics
Nonlinear
load
Vb
Vc
Va
Lsb
Lsc
Lsa IS
+
_
A
B
C
IF
VD
IL
Control Block
Fig.3 Shunt active power filter topology
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2.1. Basic Compensation Principle
Fig.4 shows the basic compensation principle of shunt active power filter. A voltage source inverter
(VSI) is used as the shunt active power filter. This is controlled so as to draw or supply a compensating current
Ic from or to the utility, such that it cancels current harmonics on the AC side i.e. this active power filter (APF)
generates the nonlinearities opposite to the load nonlinearities [3].
Fig.4 Single line diagram of the shunt active power filter showing power flow
Total instantaneous power drawn by the nonlinear load can be represented as:-
pL(t) = fp ( )t + rp ( )t + hp ( )t
Where,
pf(t) - instantaneous fundamental (real) power absorbed by the load,
pr(t) – instantaneous reactive power drawn by the load, and
ph(t) – instantaneous harmonic power drawn by the load.
In order to achieve unity power factor operation and drawing sinusoidal currents from the utility, active power
filter must supply all the reactive and harmonics power demand of the load. At the same time, active filter will
draw real component of power (PLoss) from the utility, to supply switching losses and to maintain the DC link
voltage unchanged.
Power components (reactive and the harmonic) should be supplied by the active power filters i.e.
cp ( )t = rp ( )t + hp ( )t
Fig.5 Waveform for Actual Load Current (A)
Desired Source Current (B) and
The Compensating Filter Current (C).
2.2. Estimation of Reference Source Current
From the single line diagram shown in fig.2
is(t) = iL(t) - ic(t) (1)
Where,
is(t), iL(t), ic(t) are the instantaneous value of source current, load current and the filter current.
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And the utility voltage is given by
vs(t) = mV sinωt (2)
Where,
vs(t) − is the instantaneous value of the source voltage,
Vm − is the peak value of the source voltage.
If non-linear load is connected then the load current will have a fundamental component and the harmonic
components which can be represented as – iL(t) = n n
n=1
I sin(nωt + )
1 1I sin(ωt + ) + n n
n=2
I sin(nωt + )
(3)
Where, I1 and 1 are the amplitude of the fundamental current and its angle with respect to the fundamental
voltage, and
In and n are the amplitude of the nth harmonic current and its angle.
Instantaneous load power Lp (t) can be expressed as–
L Lsp (t) = v (t) i (t)
= mV sinωt 1 1I sin(ωt + ) +
mV sinωt n n
n=2
I sin(nωt + )
= fp ( )t + rp ( )t + hp ( )t (4)
= fp ( )t + cp ( )t (5)
In the equation (4) and (5)
fp ( )t is the real power (fundamental),
rp ( )t represents the reactive power and
hp ( )t represents the harmonic power drawn by the load.
For ideal compensation only the real power (fundamental) should by supplied by the source while all other
power components (reactive and the harmonic) should be supplied by the active power filters i.e. cp ( )t =
rp ( )t + hp ( )t
The total peak current supplied by the source
Imax = Ism + IsL (6)
Where, Ism = I1 1cos
and IsL is the loss component of current drawn from the source.
If active power filter provide the total reactive and harmonic power, then is(t) will be in phase with the utility
and pure sinusoidal. At this time, the active filter must provide the following compensation current:
Ic(t) = IL(t) – is(t) (7)
Hence, for the accurate and instantaneous compensation of reactive and harmonic power it is very necessary to
calculate the accurate value of the instantaneous current supplied by the source.
Is(t) = Imax sinωt (8)
Where, Imax (= I1 1cos + IsL) is the amplitude of the desired source currents. The phase angles can be obtained
from the source voltages. Hence, the waveform and phases of the source currents are known and only the
magnitude of the source currents needs to be determined.
The peak value or the reference current Imax is estimated by regulating the DC link voltage of the inverter. This
DC link voltage is compared by a reference value and the error is processed in a PI controller. The output of the
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PI controller is considered as the amplitude of the desired source currents and the reference currents are
estimated by multiplying this peak value with the unit sine vectors in phase with the source voltages.
III. SERIES ACTIVE POWER FILTER (SERIES APF)
Series active power filters operate mainly as a voltage regulator and as a harmonic isolator between the
nonlinear load and the utility system. The series connected filter protects the consumer from an inadequate
supply voltage quality. This type of approach is especially recommended for compensation of voltage
unbalances and voltage sags from the ac supply and for low power applications and represents economically
attractive alternatives to UPS, since no energy storage (battery) is necessary and the overall rating of the
components is smaller. The series active filter injects a voltage component in series with the supply voltage and
therefore can be regarded as a controlled voltage source, compensating voltage sags and swells on the load side.
In many cases, the series active filters work as hybrid topologies with passive LC filters. If passive LC filters are
connected in parallel to the load, the series active power filter operates as a harmonic isolator, forcing the load
current harmonics to circulate mainly through the passive filter rather than the power distribution system. [3, 4,
7, 9]
Non-linear
Load
Vc
+_
shunt
passive
filter
series
Active
filter to
compensate
voltage
disturbances
sinusoidal
source
Fig.6 Filter voltage generation to compensate voltage disturbances
Fig.6 shows how the series active filter works to compensate the voltage harmonics on the load side and Fig.7
shows the connection of a series active power filter.
n
Va
Vb
Vc
Non-
linear
Loads
C1
C2
Ta
Tb
Tc
Series active power
filter
passive filter
fifth harmonic
passive filter
seventh harmonic
Fig. 7 Series active power filter topology with shunt passive filters
3.1. Basic Compensation Principle
Fig.8 shows the basic compensation principle of series active power filter. A voltage source inverter
(VSI) is used as the series active power filter. This is controlled so as to draw or inject a compensating voltage
Vc from or to the supply, such that it cancels voltage harmonics on the load side i.e. this active power filter
(APF) generates the distortions opposite to the supply harmonics [4].
Fig.9 shows the different waveforms i.e. source voltage, desired load voltage and the compensating voltage
injected by the series active power filter which contains all the harmonics, to make the load voltage purely
sinusoidal. This is the basic principle of series active power filter to eliminate the supply voltage harmonics.
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Fig.8 Basic compensation principle of series active power filter
.
Fig.9 Waveforms for the Supply Voltage (Vs)
Desired Load Voltage (Vl), and
The Compensating Voltage (Filter Voltage- Vc)
3.2. Estimation of Reference Voltage
This Section introduces the control algorithm of the series active power filter, which compensates for harmonics
and reactive power. The three-phase voltages va, vb and vc and currents ia, ib and ic for the three-phase three-wire
power distribution system is shown in Fig.10[11]-[10]-[4].
Fig.10 Circuit configuration for series active power filter
The three-phase load voltages vL(a,b,c) and the three-phase source currents is(a,b,c) are represented as:
La
L(a, b, c) Lb
Lc
v
v = v
v
,
sa
s(a, b, c) sb
sc
i
i = i
i
(1)
The load voltage vector L(a, b, c)v and the source current vector s(a, b, c)i of (1) are transformed into 0 co-
ordinates by the substituting (3) into (2) as
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La Lα
L(α, β, 0) Lb Lβ
Lc L0
v q
v = T v = q
v q
sa
s(α, β, 0) sb
sc
i
i = T i
i
=
sα
sβ
s0
i
i
i
(2)
Where,
1 -1 2 -1 2
2
T = 0 3 2 - 3 2
3
1 2 1 2 1 2
(3)
The active power p can be expressed as (4) by the inner product of the load voltage vector L(α, β, 0)v and the
source current vector s(α, β, 0)i of (2), where the active power p is the instantaneous active power at the load side
of the CT in Fig. 10.
L(α, β, 0) s(α, β, 0) Lα sα Lβ sβ L0 s0p = v i = v i +v i +v i (4)
Also, the reactive power L(α, β, 0)q is represented as (5) by the cross product of L(α, β, 0)v and s(α, β, 0)i
L(α, β, 0)q = L(α, β, 0)v s(α, β, 0)i (5)
( , , 0) L(α, β, 0) s(α, β, 0)v iLq q
(6)
Where, q is the instantaneous reactive power at the load side of the CT in Fig.10.
For a three-phase system without zero sequence voltage and current, i.e.
a b cv +v +v = 0 And a b ci +i +i = 0
L0 a b c
1
v = (v + v + v ) = 0
3
s0 a b c
1
i = (i +i +i ) = 0
3
,
Equ. (4) and (5) can be expressed as follows:
L(α, β, 0) s(α, β, 0) = Lα sα + Lβ sβp = v i v i v i (7)
L(α, β, 0)q = L(α, β, 0)v s(α, β, 0)i =
Lα
Lβ
L0
q
q
q
=
L L
s s
0
0
v v
i i
(8)
From (1)–(5), the active voltage vector p(α, β, 0)v and the reactive voltage vector q(α, β, 0)v are defined as follows:
p(α, β, 0) (α, β, 0)
(α, β, 0) (α, β, 0)
p
v = i
i i (9)
(α, β, 0) (α, β, 0)
q(α, β, 0)
(α, β, 0) (α, β, 0)
q i
v =
i i
(10)
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The p(α, β, 0)v represents the parallel component of the load voltage vector L(α, β, 0)v to the current vector s(α, β, 0)i ;
q(α, β, 0)v represents the perpendicular component of the load voltage vector L(α, β, 0)v to the current
vector s(α, β, 0)i . As a result, the load voltage vector is represented by the sum of the active voltage vector
p(α, β, 0)v and the reactive voltage vector q(α, β, 0)v as follows:
L(α, β, 0) p(α, β, 0) q(α, β, 0)v = v +v (11)
The active voltage vector p(α, β, 0)v is induced as follows, using the projection of the load voltage vector
L(α, β, 0)v onto the current vector s(α, β, 0)i :
L(α, β, 0) s(α, β, 0)
p(α, β, 0) i L(α, β, 0) s(α, β, 0)
2
s(α, β, 0)
v i
v = projv = i
i
(12)
The reactive voltage vector q(α, β, 0)v , which is perpendicular to the active voltage vector p(α, β, 0)v , is also induced
through (13)–(16):
L(α, β, 0) L(α, β, 0) s(α, β, 0)
s(α, β, 0) L(α, β, 0) s(α, β, 0) L(α, β, 0) s(α, β, 0)
q = v i
i q = i (v i )
(13) 2 2
s(α, β, 0) L(α, β, 0)
L(α, β, 0) s(α, β, 0)
s(α,β,0) s(α,β,0)
i q p
v = i
i i
(14)
The second term of the right-hand side of (15) is the active voltage vector p(α, β, 0)v and the first term of the right-
hand side of (14) becomes the reactive voltage vector q(α, β, 0)v :
2
s(α, β, 0) L(α, β, 0) s(α, β, 0) L(α, β, 0)
q(α, β, 0)
s(α,β,0) s(α, β, 0) s(α, β, 0)
i q i q
v =
i i i
(15)
Where L(α, β, 0)q is equal to the reactive power, which is defined in the instantaneous reactive power theory. The
voltage compensation reference of the series active power filter can be represented as (16), using p(α, β, 0)v and
q(α, β, 0)v in (9) and (10):
~
s(α, β, 0) L(α, β, 0)
s(α, β, 0)C(α,β,0)
s(α, β, 0) s(α, β, 0) s(α, β, 0) s(α, β, 0)
i q
v i +
i i i i
(16)
The active power and the reactive power can be divided into DC components and , which are generated
from the fundamental components of the load voltages and the source currents, and AC components
and , which are generated from the negative sequence components and the harmonic components of the
load voltages and the source currents. If the reactive power q is replaced by the AC component of reactive
power , a new voltage compensation reference compensates for the AC component of the active power
and the reactive power .
The compensation voltage reference in αβ0 co-ordinates is obtained from (16) and the final compensation
voltage reference by transforming this compensation voltage reference in αβ0 co-ordinates into the
compensation voltage reference of three-phase co-ordinates.
* *
Cα Ca
-1* * *
C(a,b,c) Cβ Cb
**
CcC0
v v
v = T v = v
vv
(17)
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IV. SERIES SHUNT ACTIVE POWER FILTER (UPQC)
As the name suggests, the series-shunt active filter is a combination of series active filter and shunt
active filter. The topology is shown in Fig.11. The shunt-active filter is located at the load side and can be used
to compensate for the load harmonics. On the other hand, the series portion is at the source side and can act as a
harmonic blocking filter. This topology is called as Unified Power Quality Conditioner (UPQC). The series
portion compensates for supply voltage harmonics and voltage unbalances, acts as a harmonic blocking filter
and damps power system oscillations. The shunt portion compensates load current harmonics, reactive power
and load current unbalances. In addition, it regulates the dc link capacitor voltage. The power supplied or
absorbed by the shunt portion is the power required by the series compensator and the power required to cover
losses. [5, 6, 7, 8]
n
Va
Vb
Vc
Ta
Tb
Tc
C1
C2
Series Active Power
Filter
Shunt Active Power
Filter
Nonlinear
Loads
Fig.11 Unified power quality conditioner topology
4.1. UPQC Operating Principle
Distorted voltages in a 3-phase system may contain negative phase sequence, zero phase sequence as well as
harmonic components. The voltage of phase "a" can be expressed as in general.
va = v1pa + v1na + v1oa+ ka kaV sin(kwt + ) (1)
Where, v1pa is the fundamental frequency‟s positive sequence component while v1na and v1oa is the negative and
zero sequence components. The last term of equation (1), ka kaV sin(kwt + ) represents the harmonics in
the voltage. In order for the voltage at the load terminal to be perfectly sinusoidal and balanced, the output
voltages of the series active filter should be:
vah = v1na + v1oa+ ka kaV sin(kwt + ) (2)
It will be shown how the series active filter can be designed to operate as a controlled voltage source whose
output voltage would be automatically controlled according to equation (2).
The shunt active filter performs the following functions:
a) To provide compensation of the load harmonic currents to reduce voltage distortions.
b) To provide load reactive power demand.
c) To maintain the DC-link voltage to a desired level.
To perform the first two functions, the shunt active filter acts as a controlled current source and its output
current should include harmonic, reactive and negative phase sequence components in order to compensate
these quantities in the load current. In other words, if the load current of phase "a" is expressed as:
iaL = I1pm cos(ωt-θ1) +IaLn + ∑IaLk
= I1pm cosωt cosθ1+I1pmsinωt sin θ1+ IaLn + ∑IaLk (3)
It is clear that the current output of the shunt active filter should be:
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iah = I1pm sinωt sin θ1+ IaLn + ∑IaLk (4)
Hence, the current from the source terminal will be:
ias = iaL – iah = I1pm cosωt cosθ1 (5)
This is a perfect, harmonic-free sinusoid and has the same phase angle as the phase "a" voltage at the load
terminal. The power factor is unity. It means that the reactive power of load is not provided by the source.
V. CONCLUSIONS
The mathematical analysis of operation of Shunt APF, Series APF and the UPQC can be used for
effectively improving the power quality of an electrical power system. The Shunt APF has been used for
compensating the source current harmonics. The Series APF has been used for compensating the load voltage
harmonics. Whereas, the UPQC which has been used for compensating the source current and the load voltage
harmonics simultaneously. Hence, the UPQC can be used for improving the power quality effectively.
REFERENCES
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BIOGRAPHIES
Vikash Anand is pursuing the PhD Degree with specialization of “Electrical Power Systems”
in Electrical Engineering department at the National Institute Of Technology, Patna and
received his M.Tech. Degree from Madan Mohan Malaviya Technical University, Gorakhpur
(India) in the session of 2010-12. His research interest includes Power System‟s Quality
Improvement.
S. K. Srivastava received his B.Tech, M.Tech and PhD Degrees from MMM Engineering
College Gorakhpur (India), IIT Delhi (India) and UP Technical University Lucknow (India) in
the year 1986, 1993 and 2008 respectively. Presently, He is Associate Professor in the
Department of Electrical Engineering at the Madan Mohan Malaviya Technical University
Gorakhpur (India). His research interests include Power System Operation and Control, FACTS
Deregulations, Fuzzy Logic and Neural Networks application in Power System Problems.