Series Active Filter Research Articles

PV integrated universal active power filter for power quality enhancement and effective power management

This paper presents a new control scheme for solar photo-voltaic (PV) integrated universal active power filter (PV-UAPF). Here, the instantaneous power balance theory (IPBT) is proposed to extract the reference signals for shunt active filter (ShAPF) and series active power filters (SeAPF). Thereby, ShAPF will act as a pure sinusoidal voltage source and SeAPF will act as a pure sinusoidal current source. In the IPBT control scheme, the frequency locked loop (FLL) based modified reduced order generalized integrator (MROGI) is proposed to extract positive and negative sequence components (PNSC) and phase angle during adverse grid conditions. Also, the PV integration at the DC link will reduce demand on the supply system thereby reduces the burden on the utility grid. Hence, the proposed system combines both the benefits of clean energy generation along with power quality improvement. To validate the performance of the proposed system, simulation is developed in MATLAB, and results are verified. Also, the system performance is then verified in the hardware setup under various disturbances such as voltage sag/swell, load distortion, and change in PV power.

Power Quality Enhancement in Grid-Connected PV/Wind/Battery Using UPQC: Atom Search Optimization

Nowadays, the integration of hybrid renewable energy system (HRES) in grid connected load system are encouraged to increase reliability and reduce losses. The HRES system is connected to the grid system to meet required load demand and the integrated design creates the power quality (PQ) issues in the system due to non-linear load, critical load and unbalanced load conditions. Hence, in this paper, atom search optimization (ASO) with unified power quality conditioner (UPQC) is designed to solve the PQ issues in HRES system. The main objective of the work is the mitigation of PQ issues and compensate load demand in HRES system. The PQ issue problems are solved with the help of UPQC device in the system. The UPQC performance is increased by introducing fractional order proportional integral derivative (FOPID) with ASO based controller in series and shunt active power filter to mitigate PQ issues of current and voltage. Initially, HRES is designed with photovoltaic (PV) system, wind turbine (WT) and battery energy storage system (BESS) which connected with the load system. To analysis the presentation of the proposed controller structure, the non-linear load is connected with the system to create PQ issues in the system. The PQ issues are mitigated and load demand is reimbursed with the assistance of HRES system. The proposed method is employed in the MATLAB/Simulink platform and performances were analysed. Three different cases are used to validate the performance of the proposed method such as Sag, Swell, and disturbances. Additionally, total harmonic distortion (THD) is analysed. The proposed method is compared with existing methods of proportional integral (PI) controller, gravitational search algorithm (GSA), biogeography based optimisation (BBO), grey wolf optimization (GWO), extended search algorithm (ESA), random forest algorithm (RFA) and genetic algorithm (GA).

Coordinated control strategy of UPQC by dynamic collaborative task-solving scheme based on multi-agent system

The conventional unified power quality conditioner (UPQC) includes a series active power filter (SAPF) and a parallel active power filter (PAPF). The former is used for voltage compensation, whereas the latter is used for harmonic and reactive power compensation. Because the SAPF always maintains an idle state, the UPQC function is relatively independent, and its utilization rate is low. To improve the UPQC performance more efficiently, a coordinated control strategy for UPQCs is established using a dynamic collaborative task-solving scheme based on a multi-agent scheme is proposed. First, the dynamic collaborative task-solving scheme based on a multi-agent system is illustrated. Next, the theoretical analysis of reactive power flow in a UPQC is discussed. Considering that no power quality problems such as voltage sag exist on the series side of the UPQC, the SAPF is used for reactive power compensation, and the PAFP is used for harmonic compensation based on the coordinated control strategy. To verify the validity and feasibility of the proposed control strategy, a simulation model is constructed in Simulink. The simulation results demonstrate the feasibility and validity of the proposed coordinated control strategy. The experimental results prove that the SAPF and PAPF can compensate for the reactive power and harmonics, respectively. The proposed strategy can be employed to improve the power quality of the microgrid effectively. Furthermore, it improves the comprehensive compensation performance of UPQCs and provides a new method for engineering applications.

DVR-based power quality enhancement using adaptive particle swarm optimisation technique

This paper proposes a heuristic control of the series active power filter for power quality enhancement. In the context of power quality, the series active filter is better utilised as a voltage source controller contrary to its conventional usage as variable impedance. The present day utility system as a linear model is unsatisfactory and the steps are laid down to discuss utility systems as a nonlinear model. This paper deals with comparative analysis of particle swarm optimisation (PSO) and its contemporary modified PSO algorithms modified particle swarm optimisation (MPSO), and adaptive particle swarm optimisation (APSO). The harmonic reduction in the source current and sags/swells mitigation in the load voltage is carried out with the optimal tuning of the PI controller. The series active power filter as a harmonic suppressor with a specific reference controlled strategy is discussed in this paper. The synchronous reference frame (SRF) theory and its modified versions are used to generate a compensating signal. The hysteresis band current controller (HBCC) is used to perform the switching operation of voltage source inverter. Simulations are carried out in the MATLAB/Simulink environment.

Series active power filter functioning study under conditions of different indicators of power quality deviation

Series active power filter functioning study under conditions of different indicators of power quality deviation

Suppression of Supply Current Harmonics of 18-Pulse Diode Rectifier by Series Active Power Filter with LC Coupling

The reported research aims at improving the quality of three-phase rectifier supply currents. An effective method consists of adding properly formed booster voltages to the fundamental supply voltages using a series active filter. In the proposed solution, the booster voltages are generated by three single-phase systems consisting of inverters, LC filters, and single-phase transformers. The application of LC couplings ensures low emission of disturbances, but may provoke compensator stability problems. The article presents the current control system for a series active filter designed to suppress the dominant harmonics in the supply currents of an 18-pulse rectifier, without interference into fundamental current components. A proportional control is proposed in combination with integral terms implemented in the orthogonal coordinate systems, which synchronically rotate with frequencies equal to those of the harmonic components to be eliminated. The use of complex gains in integral terms allows a simple phase correction of the output signals. A description is given of the method to determine controller parameters based on the mathematical model of the control object. Sample results of experimental tests performed in steady-state and transient conditions are included to illustrate the quality of performance of the series active filter as compared to the results recorded for the rectifier alone, and for the rectifier with additional line reactor. The applied control method of active filter significantly reduces harmonic distortion of the grid current, which is particularly advantageous at nonideal supply voltage and low loads.

Comparison of Various Control Strategies for UPQC to Mitigate PQ Issues

In this manuscript, numerous intelligent projected methods have been implemented to enhance UPQC device power quality (PQ) problems. The numerous intelligent methods are artificial neural network (ANN) controller, fuzzy logic controller (FLC), neuro-fuzzy controller (NFC) and adaptive neuro-fuzzy interference system (ANFIS). In addition, numerous optimization control methodologies are used to series active power filters and shunt active power filters. The intelligent control methods were implemented in the MATLAB/Simulink platform, and the efficacy of the anticipated technique is investigated via the comparison investigation with the conservative methods. The performance of adaptive ANFIS is used for enlightening the performance of PQ of the UPQC device. Lastly, the projected method of simulation is investigated and to mitigate the voltage sag/swell in UPQC device than the available approaches.

Harmonic effects optimization at a system level using a harmonic power flow controller

Increase of nonlinear loads in industries has resulted in high levels of harmonic currents and consequently harmonic voltages in power networks. Harmonics have several negative effects such as higher energy losses and equipment life reduction. To reduce the levels of harmonics in power networks, different methods of harmonic suppression have been employed. The basic idea in all of these methods is to prevent harmonics from flowing into a power network at customer sides and the point of common coupling (PCC). Due to the costs, none of the existing mitigating methods result in a harmonic-free power system. The remaining harmonic currents, which rotate in a power network according to the system impedances, may not necessarily result in an optimum harmonic power flow in terms of harmonic undesirable results such as harmonic losses or harmonic over voltage/current due to possible resonances. This paper proposes a new method to control the flow of the remaining harmonics at a power system level such that the effects of harmonics such as losses are optimized. This task is achieved by the use of series active power filters controlled in a different manner from their conventional methods. In this new application, the series active power injects a controlled harmonic voltage into a power system (e.g., a line, transformer, or other elements) to control the harmonic current (power) flow such that the overall performance of the power system is improved in terms of harmonic effects. The series active power filter in this new application is named as harmonic power flow controller (HPFC). In this paper, the theory, structure, applications, and the basics of the control method of a HPFC are described. To investigate the effects of the HPFC on the power network harmonics, an HPFC is used in the 14-busbar IEEE test system. To make the proposal more practical, an HPFC is designed for Iran north-west transmission system to alleviate the harmonic problem in this region. Simulations are carried out to show the effectiveness of the HPFC. Simulation results show that the HPFC can control the harmonic currents (power) and voltage consequently. In this paper, several control algorithms for an HPFC are also considered to achieve the desired harmonic voltages levels.

Study of Three-Phase Shunt Active Power Filter based on Deadbeat Control Method

As electrical power converting circuits are widely used in power grid, the harmonic waves are produced in electrical power system, and harmonic waves also causes the decrease of electrical power quality and have adverse effect to the electrical equipment. In order to ease these disadvantageous influences, on the basis of analysing existing series and shunt active electric power filter, a direct current control method based on deadbeat control strategy is proposed in the paper. The principle of deadbeat control method was illustrated first, then a simulation model was built to prove the effectiveness of the method. The simulation result indicated the shunt active filter based on deadbeat control method can obviously improve power quality.

Energy transmission control for a Gridconnected modern power system Non-Linear loads with a Series Multi-Stage Transformer Voltage Reinjection with controlled converters

The effective way of energy transmission plays a key factor in improving the overall transmission systems efficiency. Many methods are proposed to control the reactive power flow, voltage fluctuations and power factor improvement, The proposed converter topology gives a much significant improvement in transmission systems performance which includes multistage transformers control with the controlled converters along with the series active filters. The overall control strategy which involves the Multistage Voltage Re-Injection Transformer Controlled Converters (MSVRITCC) to reinject the voltages into the grid to compensate the voltages and remaining parameters and power flow control. The proposed topology improves the grid security, flexibility in reaching the desired load requirements with grid adaptability and reduces THD values into a significant values and made the control of power conditioning circuit flexible and easy to perform the voltage compensations in grid to load connected applications. The binary control is used to trigger the power converter circuits which made the controlling much simpler.

A Harmonic Detection Method of UPQC Based on LSL Algorithm in Photovoltaic Microgrids

Photovoltaic microgrids have discontinuity and intermittency issues that affect the load current amplitude and frequency, and this leads to disturbances. The unified power quality conditioner (UPQC) combines a series active power filter (SAPF) and a parallel active power filter (PAPF), and therefore, it has the advantages of SAPF and PAPF to treat power quality problems. Considering detection precision and response speed, and to meet the fast speed and accuracy of PAPF harmonic detection, the algorithm principle of adaptation and least-squares lattice (LSL) is analyzed. A new harmonic detection method of three-phase circuit based on LSL adaptive algorithm is proposed. The two other harmonic detection methods between least mean square and instantaneous power theory based are compared using the Simulink simulation platform. The compensation effect of LSL is more stable and better than the two other methods. The experimental results also indicate that the new method based on LSL can accurately detect and compensate the harmonic component in photovoltaic microgrids in real time. Therefore, this harmonic detection method based on LSL can be used in the practical engineering applications, and it provides a new method for harmonic detection of UPQC PAPF.

Application of Fuzzy Controller for Improvement of Power Quality using UPQC

Generally, one of the custom power device in FACTS called unified power quality conditioner, which is used to compensate the voltage and current-related Power Quality issues in the distribution systems. The proposed UPQC technology have an advantage of reduced dc-link voltage without compromising its compensation capability. This new method also helps to meet the requirement of dc-link voltage for the shunt and series active filters of the UPQC. This type of topology has a capacitor in series with the interfacing inductor across the shunt active filter for filtering purpose, and the system neutral is also considered and directly connected to neutral of distribution system avoid the requirement of the fourth leg in the voltage source inverter. This paper also presents a concept for improving power quality of a power distribution system such as an FUZZY logic controller along with the UPQC control strategy. The simulation results are compared for both conventional PI controller and FUZZY controller.

Series active power filter supplied by fuel cell for mitigating power quality issues

<div data-canvas-width="174.49288953839948">In this paper, the combination of the series active power filter (SAPF) with a fuel cell (FC) source is deliberated. The FC based on the SAPF aims to compensate voltage deviations or disturbances that occur in the system caused by power quality issues. The proposed system consists of a fuel cell source connected to the DC l ink through two DC-DC converters, the first extracts the maximum power of the FC source through pulse width modulation (PWM) signals generated from the maximum power point tracker (MPPT) controller. Thus, the second converter is used to regulate the high voltage side of the converter through closed control loops, in addition to a voltage source inverter (VSI) and a series injection transformer. Despite of fluctuations of the DC link during the compensation of the needed energy, MPPT and closed control loops generate PWM signals to the switching devices of DC-DC boost converters in order to extract maximum fuel cell power and to maintain the bus voltage within its limits and around its reference values respectively. The proposed topology is simulated in MATLAB/Simulink software, where simulation results show that the proposed FC based SAPF can efficiently reduce problems of voltage sags-wells and harmonics.</div>

Unit vector template generator applied to a new control algorithm for an UPQC with instantaneous power tensor formulation, a simulation case study

<span>In this paper we present a new algorithm to generate the reference signals to control the series and parallel power inverters in an unified power quality conditioner “UPQC” to enhance power quality. The algorithm is based in the instantaneous power tensor formulation which it is obtained by the dyadic product between the instantaneous vectors of voltage and current in n-phase systems. The perfect harmonic cancelation algorithm “PHC” to estimate the current reference in a shunt active power filter was modified to make it hardy to voltage sags through unit vector template generation “UVGT” while from the same algorithm it extracts the voltage reference for series active power filter. The model was validated by mean of simulations in Matlab-Simulink®.</span>

Series active power filter supplied by fuel cell for mitigating power quality issues

Series active power filter supplied by fuel cell for mitigating power quality issues

Performance of Distribution Grid Connected Solar Photovoltaic Array with Unified Power Quality Conditioner

The control of distribution grid connected Solar Photovoltaic Array with Unified Power Quality Conditioner (SPV-UPQC) is presented. The SPV-UPQC comprises of a solar photovoltaic array, a shunt active power filter (APF) and series APF. In UPQC, the series and shunt Active Power Filters (APFs are connected in back to back with a common DC-bus capacitor. The shunt active compensator is used to extracts the power from solar PV array as well as compensates load current harmonics. The Synchronous Reference Frame (SRF) based control theory is used in shunt active compensator for extracting fundamental load active current component. The Unit Vector Template (UVT) technique is used in series active compensator. The series active compensator mitigates grid voltage sags and swells conditions by injecting voltage in phase or out of phase at the Point of Common Coupling (PCC) respectively. The proposed system performs both the transfer of active power and power quality enhancement simultaneously. The performance of the test system are examined under steady-state condition, grid voltage fluctuations and varying solar irradiation conditions by detailed simulation in MATLAB/Simulink software.

Robust control of series active power filters for power quality enhancement in distribution grids: Simulation and experimental validation

This paper presents a simulation study and an experimental implementation of a single-phase Series Active Power Filter (SAPF) for the mitigation of harmonics in the load voltage. The aim is to regulate the injection voltage of the SAPF to compensate the grid voltage via the injection transformer in addition to maintaining the load voltage stable. The control strategies investigated in this work include Backstepping Sliding Mode Control (BSMC) and a neuro-fuzzy controller based on ANFIS (Adaptive Neuro-Fuzzy Inference System) l. The proposed control strategies for the single-phase SAPF are initially evaluated in simulations under MATLAB/Simulink and then validated on a laboratory-scale hardware experimental set up consisting of a source and a single-phase SAPF. A comparative study of these controllers with respect to their performance and robustness in mitigating power quality against voltage disturbances and harmonics is presented. Both simulation and experimental results have demonstrated that ANFIS-based controller was able to achieve superior performance and a lower total harmonic distortion (THD) as compared to the other control methods.

An improved method for harmonic mitigation and stability improvement of the grid-connected inverters under local load variation and weak grid condition

Variable voltage and current harmonics appear to be critical challenges for grid-connected inverters at the point of common coupling (PCC). The nonlinear local load and grid impedance variations contribute a lot to the problem. In this paper, a novel control strategy is proposed using the variable virtual admittance (VVA) and series active filter concepts capable of improving harmonic mitigation and stability in grid-connected inverters. The magnitude and phase angle of the VVA are adaptively determined according to the local load variation. Moreover, the series active filter injects a series voltage to reduce the grid impedance effect. The proposed control method can be simply implemented, where sinusoidal grid-injected current and sinusoidal local load voltage can also be achieved under local load variation and weak grid condition. The theoretical approach is verified using several simulation case studies in Matlab/Simulink software.

APPLICATION OF ANFIS CONTROLLER TO 3-LEVEL NPC BASED APF TO IMPROVE POWER QUALITY

Nowadays, the improvement of power quality is the major concern in power system scenario. As per literature analysis so far a huge number of technique implemented to improve power quality of the system. Out of these, the FACTS controllers plays a key role. This paper is presents a concept of series and shunt active filters implemented with 3-level inverters to reduce the harmonic distortions. The series active filter control structure is implemented with system and load voltages, the reference currents required for shunt active filter is implemented using PQ-control theory. To get better improvement of power quality and harmonic distortion, the series and shunt controllers are implemented with ANFIS controller. This proposed system is tested and verified in MATLAB/SIMULINK.

Power System Distortion Mitigation by Using Series Active Power Filter

The power quality improvement faces different significant problems due to the wide use of power electronics and voltage instability. To overcome these different power quality problems, an active power filter is used. The active power filter in general has four main categories, shunt, series, unified power quality conditioner and hybrid active power filter. The shunt active power filter is usually used to mitigate source current harmonics and compensate reactive power for power factor improvement. The series active power filter is usually used to mitigate voltage problems (sags, swells, transients, dips, distortions….). The unified power quality conditioner is used for all voltage and current problems. In this paper, the three phase three-wire series active power filter is utilized alone to mitigate all power system problems (voltages and currents) for this case study, such as voltage sag, voltage swell, voltage harmonics, and source current harmonics to comply with the harmonics limits given in IEEE 519-1992, and IEC 61000-4-7 standards. The source current harmonic problem mainly exists due to, 1) distorted voltage source, and 2) non-linear loads. The series active power filter can effectively eliminate the source current harmonics in case of distorted voltage source. Consequently, the series active power filter can be used alone as a power quality improvement for all voltage and current problems as mentioned in this case study.