Performance Of Shunt Active Power Filter Research Articles

Three novel machine learning-based adaptive controllers for a photovoltaic shunt active power filter performance enhancement

This study develops three new machine learning-based algorithms using the SVR prediction approach. The overall objective is to enhance the performance of the PV shunt active power filter (PV-SAPF) in order to successfully fulfil its multi-functionality in terms of PV power generation along with power quality upgrades. The first technique, named "SVR-INC MPPT", incorporates an ML-based duty cycle prediction function, which is intended to speed up the MPP finding process. The algorithm then switches to the INC approach, guaranteeing an accurate steady-state response. The second and third techniques are the ML-based Adaline for DC voltage regulation, and the ML-based Adaline SRF strategy for reference currents generation. The adopted approaches are based on the prediction of two weights performing the actions of the proportional and integral of DC voltage controller, and nine weights for the fundamental currant extraction. The advantage lies in overcoming the Adaline-based algorithm's limitations, requiring an on-line large number of iterations. Three simulation scenarios along with six controllers based on classical and intelligent techniques, are adopted to prove the effectiveness of the proposed ML-controllers. The results display (i) an accurate and immediate ML-based harmonics identification (minimizing the extraction error by up to 99% compared to the Adaline approach). (ii) a response time reduction range from 65% to 100%, of the ML-based DC voltage output controller compared to the PI-based one. (iii) a THD range from 2.41% to 4.45%. (iv) 20 ms and 0% of PV power response time and overshoot, respectively (v) DC voltage overshoot range from 0.04% to 1.1%. Consequently, these three ML-based controllers offer the best options for a powerful PV-SAPF system in terms of performance tracking and harmonic attenuation. Moreover, the obtained metrics comply with IEEE-519 standard.

An optimized proportional resonant current controller based genetic algorithm for enhancing shunt active power filter performance

Current harmonics produced by nonlinear loads have destructive effects that affect the power quality of the power system and cause serious problems throughout the network. Active Power Filter (APF) is one of the best and most common solutions to reduce or eliminate harmonic disturbances; But due to the complexity and sensitivity of these filters, the accurate and fast performance of the control technologies used in it is the important and basic requirement. Therefore, by performing accurate and optimal adjustments for APF control, system performance and power quality level can be improved significantly. In this article, the design principles of Shunt Active Power Filter (SAPF) are introduced and the optimal control method of this system is explained by providing appropriate modeling. Also, as a suitable structure for the current control of the SAPF system, a Proportional-Resonant (PR) controller optimized by Genetic Algorithm (GA) is proposed. The PR controller with the capability of accurate tracking of harmonic currents and fast dynamic response is highly compatible with the SAPF system. In general, the goal is to achieve better and more appropriate performance to reduce harmonic disturbances and create a robust, faster, more accurate, flexible, stable, and optimal performance of these systems in detecting and generating compensation signals. The simulations have been done in MATLAB/SIMULINK, and also the experimental tests of this device have been done and validated in a real DSP-based SAPF. Finally, according to the results obtained under steady-state conditions with a favorable dynamic response, the Total Harmonic Distortion (THD) of the grid current has been significantly reduced from 20.2 % to 4.2 % for the R-L load and from 56.1 % to 4.5 % for the R-C load with a power factor of almost unity. These results confirm the optimal and standard performance of the proposed method.

Analysis of the Influence of the 6-Pulse Thyristor-Bridge Input Reactor Size on the Shunt Active Power Filter Work Efficiency: A Case Study

This paper presents a case study in which the influence of the 6-pulse thyristor-bridge input reactor size on the shunt active power filter (SAPF)’s work performance is investigated. The purpose of using an SAPF in the power system is in most cases for fundamental harmonic reactive power compensation, harmonics and asymmetry mitigation. The work efficiency of such a filter depends not only on the designed control system, interface filter and dc-link capacitor parameters, but also on the parameters of the electrical system in which it is connected. Therefore, it is necessary to study and know the power system (supplier and consumer sides) before its installation. For instance, in the electrical system with diode or thyristor-bridge as loads, the SAPF performance efficiency may not be satisfied due to the high rate of current change (di/dt) at the points of commutation notches. In this paper, the performed simulation and laboratory experiments show that for a better operating efficiency of the SAPF, the input reactor parameters should be selected based not only on the effective reduction in the inverter switching ripple or the control system demand, but also on the parameters of the load, such as the parameters of the diode or thyristor-bridge input reactor. Apart from the experimental demonstrations on how the input reactor size influences the SAPF work efficiency, the novelties in this paper are: the formulated recommendations on how to choose the SAPF input reactor parameters (the SAPF is more efficient in terms of harmonics, asymmetry and reactive power mitigation when the inductance of its input reactor (L-filter) is smaller than the one of the diode or thyristor-bridge input reactor); the proposed SAPF control system; the proposed expressions to compute the SAPF input reactor inductance, DC voltage and capacitor.

Hybrid One-Cycle-PI Control Algorithm for Shunt Active Power Filter in Mitigating Harmonic Currents

The quality of current waveforms, such as the presence of the harmonic components at the point of common coupling of various consumers, deteriorated due to the nonlinear load applications. Hence, a Shunt Active Power Filter (SAPF) is used to mitigate harmonic pollution in an electrical network. The heart of the SAPF operation is the current control technique. The choice of current control techniques significantly impacts the SAPF performance. As a result, a Hybrid One-Cycle-PI Control (HOCPIC) is proposed to work as a single-phase SAPF's current controller. The HOCPIC utilises a Proportional-Integral (PI) controller to minimise the error signal. As a result, the THD value of the supply current is reduced to 3.20% using the SAPF-based HOCPIC compared to 3.99% when using the SAPF-based OCC. The result proves that the SAPF-based HOCPIC performs better in compensating harmonic currents than the SAPF-based OCC.

A novel negative feedback phase locked loop-based reference current generation technique for shunt active power filter

The use of nonlinear devices introduces current and voltage harmonics into power distribution networks. The presence of harmonics, an undesirable power quality issue, causes transformer overheating, malfunctioning of sensitive loads, power losses, and significantly reduced distribution system efficiency. Therefore, harmonics mitigation in power systems has become absolutely essential and is widely addressed, utilizing shunt active power filters (SAPFs) around the globe. The performance of SAPF in generating adequate compensating current depends on the working of three control loops used for the purpose of reference current generation, dc-link voltage control, and switching pulse generation. The existing approaches for reference current generation suffer from inherent complexity and the inability to extract positive sequence signals required for obtaining synchronizing angle during source disturbance conditions. Therefore, this paper proposes a novel negative feedback phase-locked loop-based modified synchronous reference frame technique to overcome the drawback of the existing approaches. The effectiveness of the proposed approach is investigated under ideal and non-ideal grid voltage conditions with different load perturbations. The proposed control strategy is first tested using a number of simulation-based experiments and, thereafter, validated using OPAL-RT 4510 real-time digital simulator. Compared to other existing approaches, the proposed technique has offered improved results in terms of reduced total harmonics distortion.

Immunity of shunt active power filter based on improved LADRC

To improve the dynamic response speed and performance of active power filter controller, and improve the robustness, tracking ability, and disturbance rejection ability of linear active disturbance rejection controller (ADRC), an improved linear ADRC (LADRC) is proposed. First, a new error adjustment total disturbance is introduced into the linear expansion state observer to adjust the total disturbance of the linear expansion state observer. Then, on the premise of system stability, the controller is applied to the voltage outer loop of shunt active power filter (SAPF), and the mathematical model of active power filter is deduced, and it is controlled according to the first-order linear active disturbance rejection controller. Finally, through frequency domain analysis, the stability, noise immunity, and tracking performance of the improved LADRC are analyzed. Using MATLAB and Simulink simulation platform, the current stability and tracking performance of SAPF under improved LADRC control are simulated and verified, and compared with traditional methods. The simulation results show that the waveform fluctuation of A-phase voltage on the grid side of this method is relatively smooth, and the voltage on the grid side is always kept at ±50 V; the voltage curve of SAPF DC side is kept between the actual set values, about 820 V; the waveform fluctuation of A-phase current on the load side is small, which is ±220 A; the harmonic distortion rate is 4%. It is verified that this method has good tracking effect and anti-interference characteristics, which is of great significance to improve the control performance of active power filter.

Active Power Filter LCL Filter Novel Interface Control Scheme Analysis

Shunt active power filter (SAPF) has been widely used in active distribution network system. Improving the compensation performance of SAPF has become the focus of many scholars. The traditional filter interface usually adopts series resistance. In order to reduce the loss of damping resistance and ensure the compensation performance of SAPF, a new type of passive interface is adopted, and the double-loop control scheme of PI control combined with repeated control is adopted. By comparing the difference of the selected points of different feedback currents, when the feedback current is taken from the inverter, only a small damping resistance is needed to achieve good steady-state accuracy. Simulation results verify the correctness and effectiveness of the proposed scheme and the system feedback current selection method.

Shunt active power filtering with reference current generation based on dual second order generalized integrator and LMS algorithm

For reducing the carbon emissions from utility sector, it is important to improve the efficiency of network and electrical loads. Current harmonics are responsible for the degradation of the system as well as load efficiency. The propagation of current harmonics into the grid can be prevented with shunt active power filters (SAPFs). Reference current generation (RCG) is critical for SAPF operation. This paper presents the control of SAPF with RCG based on least mean square (LMS) and dual second order generalized integrator (SOGI). The two SOGIs separately process grid voltage and load current to determine the respective fundamental in-phase component (FPC) and fundamental quadrature component (FQC). FPC and FQC of grid voltage are used to determine the phase angle of fundamental grid voltage. With LMS algorithm the distorted current can be decomposed into fundamental active (FA), fundamental reactive (FR) and harmonic components. However, the dynamic response of LMS based estimation is poor when the same learning rate is used for all components. FQC of load current, estimated with SOGI, can be processed by LMS algorithm to separate FA and FR components. RCG can be implemented with the computed phase angle and FA component. In LMS algorithm, as only two components are to be separated, two different learning rates can be easily specified. This results in faster dynamic response for LMS algorithm and has consequent positive impact on RCG and SAPF operation. Also, the computational complexity is considerably reduced. The performance of SAPF with the proposed extraction algorithm is analyzed for different operating conditions and comparative analysis is carried out.

A novel optimizing PI control of shunt active power filter for power quality enhancement

In this paper, shunt active power filter (SAPF) is designed to address the problem of current harmonics in the source current arising from a nonlinear load and improve the quality of electric power. That will be by compensating reactive power and harmonic currents. The PI controller responsible for DC-link energy storage tuning was developed using the Lévy flight distribution algorithm (LFA). It is a novel, previously unused optimization approach to suggest relative gain Kp and integration gain Ki gain values for the PI controller. This approach aims to get the best dynamic performance of SAPF, speed up the convergence rate, get the fastest best stability and bypass constant voltage advancement for DC-link. The model was tested and implemented in MATLAB simulation software. The result of total harmonic distortion THD showed the efficiency of this method compared with the results of traditional PI. The design of the model in the current reference frame was based on instantaneous reactive power (pq) theory.

Parameter optimization of PV integrated Shunt Active power filter with Taguchi SNR

Abstract In this article, a better optimization method known as the Taguchi method is implemented for optimizing the designing parameters of PV integrated Shunt Active power filter (SAPF). The effect of these parameters on the performance of SAPF is also studied with the help of this method. This paper also signifies the benefits of using the Taguchi method for optimization over the existing particle swarm optimization (PSO) algorithm. SAPF is a very popular device for power quality improvement through harmonics compensation. In non-conventional energy sources, solar is most widely used dues to its cost-effectiveness over other sources. Hence, PV integrated SAPF is considered for study for this article. Incremental conductance (IncCond) based maximum power point tracking (MPPT) technique is used to extract the maximum power from PV panel. Performance of this PV Integrated SAPF depends on many factors like reference current generation techniques, switching pulse generation technique and selection of SAPF designing parameters, etc. To get the optimum performance from SAPF, designing parameters like gains of PI-controller, coupling impedance, and dc-link capacitor need to be optimized. PV integrated SAPF is modeled and simulated in Matlab/Simulink. SAPF parameters are optimized by using both the proposed Taguchi method and the existing PSO algorithm and their results are analyzed. Simulation results are also verified using a laboratory-developed experimental setup.

Shunt Active Power Filter Performances based on Seven-level NPC Inverter using Fuzzy and LS-PWM Control Scheme

This paper presents novel seven-level neutral point clamped (npc) shunt active power filter system based on LS-PWM and fuzzy control approaches which can eliminate current harmonics generated by nonlinear loads. Today, multi-level inverters are strongly used in the medium and high voltage applications; their advantages are low harmonic distortions, low switching losses, low electromagnetic interference, and low acoustic noise. Second, fuzzy logic techniques have been successfully employed in several power electronic applications. Fuzzy controller does not need an accurate mathematical model, can work with imprecise inputs, can handle non-linearity, and are more robust than conventional controllers. To benefit from these advantages a novel control scheme for seven-level (npc) inverter based on Fuzzy and LS-PWM technique is proposed. The reference current signals required to compensate harmonic currents use the synchronous current detection method, this technique is easy to implement and achieves good performances for harmonic compensation. The proposed shunt APF is evaluated using Matlab-Simulink software and SimPowerSystem Toolbox under transient and steady state for various operation conditions. The simulation results show the effectiveness of the proposed shunt active filter based on seven-level (NPC) inverter for improving the power quality and the superiority of combined fuzzy and LS-PWM control scheme to conventional controller in term of harmonics compensation and dynamic performances.

SAPF Parameter Optimization with the Application of Taguchi SNR Method

Non-linear devices draw non-sinusoidal currents from the source; hence, they cause harmonic distortions in power systems. The shunt active power filter (SAPF) is a well-known method for alleviating current harmonics, compensating the reactive power and improving the power factor; however, the effective design of an SAPF is quite challenging and a thrust area of research. The current controlling technique, switching pulse generation technique and parameter selection are cumbersome tasks in SAPF design. SAPF performance depends on the proper selection of many parameters, such as filter interfacing impedance, DC-link capacitor and PI-controller gains. The effect of these parameters on the performance of SAPF has been studied and optimum values have been obtained by using the Taguchi method. This paper also indicates the benefits of using the Taguchi method compared with existing genetic algorithm (GA) for optimizing the parameters of the SAPF. An instantaneous reactive power theory (IRPT)-based SAPF has been modeled and simulated in MATLAB/Simulink. The SAPF’s parameters have been optimized by using the both proposed Taguchi SNR and the existing GA method. With optimized values of parameters results have been obtained, analyzed and the superiority of the proposed Taguchi method over the existing GA method is discussed. The simulation results were also validated with experimental results.

Synchronization of Active Power Filter under Distorted Grid Conditions

Advancement in technology has resulted in increased use of electrical energy. The trend of using energy-saving appliances is also increased considerably. Harmonic currents have been increased in power systems due to the large-scale use of nonlinear loads. Shunt Active Power Filter (SAPF) is the most widely used technique for the compensation of current harmonics. Under adverse grid conditions performance of SAPF is affected badly. In this paper, a modified synchronous reference frame theory is proposed for current reference generation by incorporating an advanced phase-locked loop technique for the estimation of frequency and phase. The proposed approach results in an accurate extraction of reference current in the presence of various grid disturbances. Matlab/Simulink environment is used for evaluating the performance. The results achieved show excellent performance of the proposed technique in terms of reducing harmonics distortion and dynamic response. The total harmonics distortion of the compensated source current is reduced to a value well within the limits of the IEEE-519 standard.

Recital analysis of multilevel cascade H-bridge based active power filter under load variation

This paper investigates a 13-level cascaded H-bridge (CHB) converter for shunt active power filter (SAPF) application to minimize the total harmonic distortion (THD) of source current under load variation. The converter configuration comprises of six H-Bridge cells per leg. Carrier-based phase disposition PWM is used as a modulation strategy to control the switches of 13-level CHB topology. An instantaneous real and reactive power technique based harmonic current extraction method is implemented to extract the reference currents. The proportional-integral controller is implemented to control the DC voltage of the SAPF. The proposed 13-level CHB SAPF performance is compared with two-level voltage source SAPF, three-level CHB SAPF, five-level CHB SAPF and nine-level CHB SAPF. The proposed work is implemented using Matlab/Simulink. The comparative performance analysis of THD, harmonics, active power, reactive power and power factor are presented.

Investigations on shunt active power filter in a PV-wind-FC based hybrid renewable energy system to improve power quality using hardware-in-the-loop testing platform

The current power distribution system involves usage of nonlinear loads that cause power quality problems. Further, the penetration of renewable energy sources is increasing in the power networks to satisfy the consistently rising energy demand, which changes the traditional network plan and control drastically. This paper presents an intelligently controlled hybrid energy system (HES) integrated with shunt active power filter (SAPF) to address the power quality problems. Renewable sources like-Wind, PV and fuel cell (FC) are integrated into HES and are regulated using artificial intelligence techniques that are also implemented for maximum power point tracking (MPPT) in both PV and wind energy systems. The dynamic performance of SAPF is optimized using fuzzy logic, neural network and adaptive neuro-fuzzy inference system (ANFIS) based control algorithms. These controllers provide the smooth DC-link voltage and minimize the total harmonic distortion (THD) produced by the balanced/unbalanced and nonlinear loads. Comparison of these reveal that the ANFIS based algorithm provides minimum THD. The system is tested in real-time using hardware-in-the-loop (HIL) setup. The control schemes are executed on FPGA based OPAL-RT4510computational engine with microsecond step.

Adaptive Frequency-Based Reference Compensation Current Control Strategy of Shunt Active Power Filter for Unbalanced Nonlinear Loads

The shunt active power filter (SAPF) is an effective means for the modification of power quality. However, the compensation performance of SAPF would be deteriorated when the unbalanced nonlinear loads are present in the power system. To enhance the compensation performance of SAPF, the adaptive frequency-based reference compensation current control strategy is proposed in this paper. The proposed solution procedure can be divided into three stages including adaptive frequency detection, phase synchronization, and adaptive compensation. With the tracking of power system frequency, the phase synchronization for the SAPF compensation can be effectively modified under the power variation of unbalanced nonlinear loads. Based on the correct synchronization phase angle, the reference compensation current of SAPF can be accurately obtained with the adaptive linear neural network (ALNN) in the stage of adaptive compensation. In addition, the direct current (DC)-link voltage of SAPF can also be effectively regulated to maintain the compensation performance. To verify the effectiveness of the proposed adaptive frequency-based reference compensation current control strategy, the comprehensive case studies implemented with the hardware-in-the-loop (HIL) mechanism are performed to examine the compliance with the specification limits of IEEE Standard 519-2014. The experimental results reveal that the performance of proposed SAPF control strategy is superior to that of the traditional instantaneous reactive power compensation control technique (p-q method) and sliding discrete Fourier transform (DFT).

Mathematical and Experimental Investigation on Advanced PLL for Cascaded H-Bridge Multilevel Inverter in Active Filtering Application

Cascaded H-bridge multilevel inverter (CHB-MLI)-based shunt active power filter (SAPF) is one of the finest solutions for power quality improvement in case of medium-voltage distribution sector. Performance of SAPF degrades due to the presence of DC offset and harmonics in the grid voltage since this will result phase angle and frequency error. Therefore, modified single-phase synchronous reference frame theory comprising of advanced PLL is presented in this article. The advanced PLL can track frequency and phase angle accurately even though source voltage is having DCor harmonic content. A detailed mathematical modeling and stability analysis of this PLL is presented using Routh-Hurwitz criteria. A novel systematic design procedure using gravitational search algorithm (GSA) and an Eigen value analysis is proposed for calculating optimal PLL parameters. Closed-loop SAPF control stability is tested using root-locus analysis. An extensive experimental analysis of the proposed control applied to CHB-MLI-based SAPF has been performed under distorted source voltage and non-linear loading conditions to show the effectiveness of the proposed control over recently published work. Source current maintains its sinusoidal shape, properly synchronized with grid voltage and having distortion limit in compliance with IEEE-519 standard irrespective of source voltage conditions during the operation of SAPF.

A novel serial structure repetitive control strategy for shunt active power filter

PurposeThe purpose of this paper is to propose a novel serial structure repetitive control scheme for shunt active power filter (SAPF) to improve the steady-state accuracy and dynamic performance of SAPF. The novelty of this scheme lies in the reconfiguration of the pole of repetitive control internal model, so that the dynamic response of the repetitive control is improved greatly.Design/methodology/approachBy analyzing the mathematical model of repetitive control, the repetitive control delay can reduce by giving up the needless poles of the internal model, and the general mk + i repetitive control can be designed through the pole configuration method. The controller can track a set of specific order harmonics.FindingsThe experimental results are coincident with the theoretical analyses, which prove the effectiveness of the proposed method on harmonic suppression and great performance in dynamic response.Practical implicationsAn APF prototype has been designed with the serial structure repetitive control proposed in this paper, and it can successfully eliminate the harmonics current of nonlinear load with faster dynamic response. Moreover, the proposed controller can be applied to any three-phase system for fast dynamic response and high tracking accuracy.Originality/valueIn this paper, the mathematical model of the repetitive control for specific set of harmonica is developed. A novel serial structure repetitive control is designed, so that the SAPF can eliminate the fundamental reactive current and specific order harmonics and speed up the dynamic response of the repetitive control.

A Dual-Function Instantaneous Power Theory for Operation of Three-Level Neutral-Point-Clamped Inverter-Based Shunt Active Power Filter

This paper proposes a simple yet effective reference current generation algorithm based on instantaneous power pq theory to enhance mitigation performance of a three-phase three-level neutral-point-clamped (NPC) inverter-based shunt active power filter (SAPF). The proposed algorithm is developed for dual functionality: generate reference current and synchronization phase to effectively govern operation of SAPF in mitigating harmonic current and compensating reactive power. Three key modifications are implemented: (1) replacement of numerical low-pass filter (LPF) with an average power detector to improve mitigation performance; (2) removal of needless reactive element to reduce algorithm complexity; and (3) integration of phase tracking feature to eliminate the needs of phase-locked loop (PLL). Simulation work of SAPF with the proposed algorithm was conducted and assessed in MATLAB–Simulink. In addition, to verify feasibility of the proposed algorithm, a laboratory prototype as constructed with TMS320F28335 digital signal processor (DSP) programmed as the controller. Performance of SAPF achieved by utilizing the proposed algorithm was thoroughly investigated and benchmarked with that demonstrated using the existing pq theory algorithm to evaluate the inherent advantages. Simulation and experimental results are obtained for different nonlinear loads and test conditions. Responses demonstrated by SAPF in both simulation and experimental works reveal superiority of the proposed algorithm over the existing algorithm.

Performance and power quality improvement based on DC-bus voltage regulation of a stand-alone hybrid energy system

This paper proposes an improved standalone configuration based on hybrid wind-PV with Lithium-ion battery bank combined with a Shunt Active Power Filter (SAPF). The hybrid system is controlled to produce the active power and to supply the load by a good power quality. The main idea of this novel configuration is to control the SAPF only to compensate the harmonic currents. In fact, the SAPF DC-side voltage and the PV system are directly connected to the common DC-bus of the hybrid system, which is regulated by the batteries through a buck-boost converter (BBC). Due to its regulation through a large Battery Energy Storage System (BESS), good dynamic response of the DC voltage is obtained, during a sudden variation in nonlinear load. Hence, the SAPF capabilities of harmonic filtering are enhanced. In addition, the proposed system is controlled to operate at the maximum power point under abrupt conditions, and to meet the load demand and maintain the output voltage and frequency at their desired values despite changes in load conditions. Finally, the SAPF performances are demonstrated through a comparison with a conventional configuration of the SAPF on various indices.