Performance Of Active Power Filter Research Articles

A comprehensive review on power quality issues and disturbances mitigation through shunt active power filters

In contemporary power systems, power quality (PQ) has become a matter of paramount concern. The challenges associated with PQ extend beyond conventional three-phase systems, encompassing the integration of various distributed generation (DG) sources like renewable energy installations, storage systems, and diverse power generation technologies such as diesel generators and fuel cells. The prevalent adoption of rapid-switching devices within the utility infrastructure has resulted in a surge of harmonics and reactive power disturbances. The increased use of harmonics-producing loads has led to several power quality issues, particularly harmonics. The distortions caused by these power quality issues must adhere to the limits established by international standards. Mitigation of these concerns is critical, and active power filters are a realistic option. However, passive filters have problems such as bulkiness, and resonance with either/both load and utility impedance, and the source impedance affects filtering properties. As a result, active power filters (APF) are designed to address the shortcomings of passive filters. Active power filters (APF) offer several advantages over passive filters, including compact size, enhanced filtering characteristics, dynamic performance, and flexible operation. The control strategy of APF strongly influences the APF performance, efficiency, and reliability. This paper presents a detailed assessment of current active filter control systems, highlighting their key features. The characteristics, performance, applicability, and implementation of various control techniques are explored and investigated.

Improved performance of a shunt hybrid active power filter by a robust exponential functional link network-based nonlinear adaptive filter control to enhance power quality

This research article details the design and implementation of a nonlinear adaptive filtering (NAF) technique using an exponential functional link network (EFLN) for a shunt hybrid active power filter (SHAPF) control to solve the current-associated power quality issues on the utility side at the distribution level of electrical power systems. Separation of the fundamental component from the harmonics, achieving unity power factor operation, reducing the reactive power drawn from the source, balancing the currents during transients, and reduction of total harmonic distortion (THD) of the source current are the issues considered to resolve. The proposed technique solves these issues by generating the sinusoidal reference current and separating the fundamental current from the harmonics. When compared to conventional and existing adaptive filtering techniques such as least mean square (LMS), least mean fourth (LMF), and variable step size LMS (VSS-LMS), the proposed EFLN-NAF method excels in terms of speedy convergence, adaptability in noise-specific environments and reduced steady-state coefficient error. MATLAB/Simulink software is utilized to perform the simulations to examine the suggested strategy for the chosen SHAPF topology both in static and dynamic scenarios. For a 15 kW and 3kVAr requirement of the nonlinear load, simulation results proved that the designed PPF for 2kVAr is able to share the reactive power with the APF, thereby reducing its rating and cost. The proposed method of filtering has been proven to be fast converging with 0.049 s, and the THD in steady state is brought to 1.32 % in steady-state and to 3.77 % during transient conditions, which are under standard limits. A hardware prototype of the experimental setup is constructed at the laboratory scale with OPAL-RT (OP4510) as the controller. With an active and reactive power demand of 1.1 kW and 210VAr, the designed PPF supplies 110 VAr, whereas the rest is supplied by the APF. The practical THD in source current is observed to be 2.081 %, which meets the standards. The results from both simulations and experiments are validated, and the efficacy of the proposed technique in mitigating the aforementioned power quality issues is proved.

Fault-tolerant shunt active power filter with synchronous reference frame control and self-tuning filter

This research proposes a novel method that combines Proportional-Integral (PI) control, Artificial Neural Networks (ANNs), and Synchronous Reference Frame (SRF) theory to improve the performance of a three-phase shunt Active Power Filter (APF) under fault situations. The main goal is to reduce power quality problems in electrical grids that are having problems, such harmonics and voltage sags. To precisely manage the APF, the reference frame in which the grid voltages and currents are synchronized is identified using the SRF theory. In order to provide quick and precise correction of voltage and current distortions, the PI controller is integrated to control the APF's compensatory action. The PI controller offers trustworthy control while running normally, but during errors or disruptions, its functionality may suffer. In order to overcome this difficulty, a self-tuning filter in the form of an Artificial Neural Network (ANN) is presented, which may adaptively modify the PI controller's settings under fault situations. To maintain ideal filter performance, the ANN constantly learns from the system's reaction and modifies in real-time. This self-adjusting feature makes sure that even in the event of grid failures, the APF maintains its ability to mitigate problems with power quality. The suggested method effectively reduces harmonics, voltage sags, and other power quality disturbances under both normal and fault circumstances, as shown by the simulation results. In complicated electrical grid systems, the combination of SRF theory, PI control, and ANN-based self-tuning provides a strong way to improve the dependability and effectiveness of three-phase shunt Active Power Filters.

Control Scheme Influence on the Performance of Shunt Active Power Filter based on Five-level NPC Inverter in Steady and Transient Conditions

This paper presents an investigation on the performance of shunt active power filter (Shunt APF) systems based on five-level neural point clamped (NPC) inverter in steady and transient conditions adopting a fuzzy control scheme. The shunt APF is operated as a current source connected in parallel with the non-linear loads to inject compensates current harmonics into the AC source. The multi-level inverters have gained considerable interests in last year’s. Five-level inverter is recommended in medium and high voltage applications; their advantages are low harmonic distortions, low switching losses, low electromagnetic interference, low voltage stress of power semiconductors and low acoustic noise. Secondly fuzzy logic has been widely used in various industrial applications. To benefit from these advantages a shunt active power filter based on five-level (NPC) inverter using fuzzy control scheme is presented in this work. To identify the reference currents, synchronous detection method (SMD) is adopted. Proportional integral voltage controller is used to maintain the dc voltage across capacitor constant and reduce inverter losses. The simulation is performed using MATLAB-Simulink software and SIMPOWERSYSTEM toolbox. The obtained results in steady and transient states illustrate the performances and the effectiveness of the proposed shunt APF system.

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.

Advanced Universal Power Quality Conditioning Systems for Stabilizing Micro-Grid’s Frequency

This paper proposes a new unified active filter to alleviate instantaneous unwanted oscillating powers as they may lead to frequency variations in weak systems. First, the paper presents negative impacts of capacitive loads on the shunt active power filter performance in compensation of instantaneous oscillating real power. Secondly, an advanced universal power quality conditioning system (AUPQS) for three-phase/four-wire systems under non-ideal waveforms is introduced. By considering the suggested compensation algorithm, the AUPQS is able to extremely suppress instantaneous oscillating powers caused by distorted-unbalanced load-terminal voltages. Moreover, an independent single-phase converter is suggested at the load-end in order to regulate the DC-link voltage. Therefore, the instantaneous oscillating powers perfectly suppress and thus, the source-end three-phase currents will be purely sinusoidal. The suggested AUPQS is used to stabilize micro grid frequency. The effectiveness and flexibility of the proposed AUPQS are confirmed by Matlab/ Simulink simulations.

Impact of Converter Topology on the Shunt Active Power Filter Systems Efficiency

This paper presents the performance of shunt active power filters (Shunt APFs) which can compensate harmonic currents generated by no-linear load based on five and seven-level neural point clamped (NPC) inverters. Multilevel inverters are currently being investigated and used in several industrial applications. Their advantages include the capability to reduce the harmonic content and decrease the voltage or current ratings of the semiconductors. On the other side, fuzzy techniques are successfully employed in various industrial applications; they represent a good alternative to traditional control systems. To benefit of all these advantages an efficient control scheme for five and seven-level Shunt APF based on multi-carrier pulse width modulation (MC-PWM) and fuzzy control approaches are adopted in this work. The fuzzy controller is designed to improve compensation capability of shunt APF by adjusting the error using a fuzzy rule. The control strategy to identify the current reference uses synchronous detection method (SMD), this technique is easy to implement and achieves good performances. The numerical simulation results carried with MATLAB-Simulink and SimPowerSystems Toolbox show the effectiveness of the proposed systems and confirm the superiority of the seven-level shunt APF compared to five-level configuration system.

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.

Evaluation of CHB MLI based shunt APF using low pass filter and self-tuning filter

The increasing demand for high-rating power supply in the distribution system causes the conventional inverter topology, six step voltage source inverter (SSVSI) unsuitable for being applied as active power filter (APF). Multilevel inverter (MLI) is generally the best suitable inverter for APF, but not all types of MLI can be used for high-voltage applications. Among the MLIs topology, cascaded H-bridge (CHB) is the best choice since it can produce output voltage more than twice the amount of DC source. Moreover, CHB MLI topology uses fewer power devices and is simple in design. Low pass filter (LPF) is a common method used for harmonic extraction in this controller. However, this method faces various problems, such as an additional need for phase lock loop (PLL) algorithm and slow transient and steady-state responses. Therefore, self-tuning filter (STF) is introduced as a new filtering method to overcome this problem. This paper evaluates CHB MLI's performance for APF using STF as a harmonic extraction. The model was developed and verified in MATLAB/Simulink. The results show that harmonic extraction using STF performs better total harmonic distortion (THD) than conventional LPF. Nevertheless, both algorithms produce THD below 5%, defined as the permissible value stated in IEEE 519.

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.

A Novel Control Strategy for Improving the Performance of Hybrid Active Power Filters

A Novel Control Strategy for Improving the Performance of Hybrid Active Power Filters

A Generalized Harmonic Extraction Algorithm Based on Multi-Window Average Filter Under Synchronous Rotating Frame

Various harmonic extraction algorithms have been proposed to improve the steady-state and dynamic performance for active power filter. However, it is difficult to select a suitable method for a certain load current scenario. This article analyses the general characteristics of the harmonic extraction based on the “frequency shift” characteristic by Park transform, and it can be transformed into a low-pass filter under the synchronous rotating frame (SRF) for design. Starting from the typical average filter, a general FIR filter structure called multi-window average (MWA) is proposed. According to the actual load current components, aiming at the shortest delay, the design process and guideline are given. Combined with SRF, the MWA structure can generalize recursive discrete Fourier transform (RDFT), cascade delayed signal cancellation (CDSC) and their derived algorithms, which proves the equivalence between time-based harmonic extraction methods and frequency-based ones. Moreover, using the MWA structure can effectively reduce the complexity of the CDSC algorithm. The experiment proves that the typical RDFT and CDSC harmonic extraction can be equivalently realized by using the SRF-based structure. Under the presence of 6 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</i> + 1 and 12 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</i> − 2 harmonics, the proposed harmonic extraction time can reach 1/4 fundamental cycle. While greatly reducing the dynamic response time, the MWA structure reveals inherent unity among various harmonic extraction algorithms for the first time.

Online Inductance Identification and FPGA-Based Real-Time Digital Control Design for APF

The harmonic suppression performance of active power filter (APF) under model predictive current control is obviously reduced, when the parameter exists a mismatch between the actual value in system and the nominal value adopted in the control. To suppress the influence of parameter mismatching, a model predictive control based on parameter identification with forgetting factor recursive least square (FFRLS) method is proposed for APF. The digital processing procedure of the FFRLS-based APF controller is detailed analyzed and designed. The identification error of inductance between identification value and the actual value is less to 6%, and the total harmonic distortion of grid current is significantly improved, especially a lower value of actual inductance. Simulation and experimental results show that the proposed method can not only effectively eliminate the influence of parameter mismatch on the control, but also result in better steady-state performance while retaining fast dynamic response.

An inductor design method based on multi-objective optimized algorithm for LCL-type shunt active power filter

The application of pulse width modulation (PWM) technology will produce a high-frequency switching ripple. Generally, it is considered to filter it with an LCL filter to ensure the compensation performance of the shunt active power filter. According to the system requirements for ripple current suppression and maximum current tracking capability, this paper first optimizes the design of the filter inductance in the LCL. Then, aiming at the shortcomings of the traditional inductor design process that is complicated and cumbersome, with repetitiveness and difficulty to obtain reliable analytical solutions, a 4-dimensional visualization based multi-objective optimized algorithm is proposed, and the ternary function expression between each design goal and known independent variables is first derived and established. And then, through the visual programming of the 4-dimensional data field, the optimal solution set that meets the multi-objective design requirements is directly given, which is intuitive, clear, simple, and practical. Finally, according to the algorithm results, the corresponding inductance was wound and applied to a 50kVA three-phase four-wire active power filter prototype. The experimental results verified the feasibility and effectiveness of the proposed design method.

TS Model-LMI Based Observer for Improving Active Power Filter Performance

To avoid the negative effects of using a control signal with a ripple, which is generated by the feedback of measured active power filter (APF) variables, a nonlinear observer is employed in this paper. The observer design, through the use of exact TS models and Lyapunov-based LMI conditions, is achieved. Both the APF output current and the DC voltage are estimated by the observer, and they are used in the cascade control feedback. In this way, high gains in the inner control loop are employed, giving place to a control signal without undesired harmonic components or overmodulation. This allows an APF performance improvement for compensation tasks and for reducing the undesired components injection to the mains. A simulation and experimental comparison between APF results using observer and APF results without using observer is presented. Better results are achieved for the observer version case, reducing the THD from 47.6% to 4.8% in experimental conditions, satisfying the IEEE Standard 519TM-2014. Also, load change tests are carried out, where the stability of the system is kept. Moreover, by using the observer, a DC voltage sensor was not required, reducing the number of system sensors.

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.

Microgrid Power Quality Improvement Using Active Power Conditioner

This paper discusses power system power quality issues and possible remedies using power electronics. Several worldwide standards This research shows how a Shunt active power filter can improve power quality in a microgrid system at the distribution level. The major goal of this study is to find an appropriate pulse generating strategy for improving the shunt active power filter's compensation capabilities. The device's compensating capability is mostly determined by the DC link capacitor voltage regulation. A fixed hysteresis current control approach has been employed in the past. An adaptive hysteresis current control technique has been developed here to improve the performance of a shunt active power filter. The suggested technique's performance has been verified in the MA TLAB/SIMULINK model platform under various operating conditions.

Novel design method for the inductor of active power filter based on four-dimensional visualization algorithm

To guarantee the compensation performance of active power filter (APF), LCL filter is usually used to filter out the switching harmonics. Due to the complicated design process, repetitive verification steps and limitations of solution set, traditional inductor design method is hard to meet the requirements perfectly. This paper firstly analyzes the inductor parameters according to the demands for suppressing the ripple current and tracking maximum current variation. Then a novel multi-objective four-dimensional visualization algorithm based design method for inductors is proposed. The ternary function representations between each design objective and three independent variables are established. On this basis, through the visualization programming, intuitive four-dimensional visualized design results are obtained. Further, analytical solution set that meet all expected objectives can be acquired by intersecting the sub-solution sets. Finally, corresponding inductors are manufactured and applied to a 50kVA APF prototype. The results have indicated the feasibility and validity of the proposed method.

Coordinated Control Strategy for Harmonic Compensation of Multiple Active Power Filters

In order to minimize the harmonic distortion rate of the current at the common coupling point, this paper proposes a coordinated allocation strategy of harmonic compensation capacity considering the performance of active power filters (APF). On the premise of proportional distribution of harmonic compensation capacity, the harmonic compensation rate of each APF is considered, and the harmonic current value of each APF to be compensated is obtained. At the same time, the communication topology is introduced. Each APF takes into account the compensation ability of other APFs. Finally, three APFs with different capacity and performance are configured at the harmonic source to suppress the same harmonic source, and the harmonic distortion rate is reduced to 1.73%. The simulation results show that the strategy can effectively improve the compensation capability of the multiple APF cascaded system to the power grid without increasing the installed capacity.

Harmonic Detection for Active Power Filter Based on Two-Step Improved EEMD

The performance of active power filter (APF) mainly depends on its harmonic detection method. Empirical mode decomposition (EMD) is applied to APF because of its effectiveness for any complicated signal analysis. Ensemble empirical mode decomposition (EEMD) can suppress mode mixing caused by EMD to a certain extent, but the amplitude and energy of fundamental is severely attenuated. To solve this problem, in this article, the causes of attenuation are discussed from the perspective of intrinsic mode functions (IMFs) energy, and an approach based on two-step improved EEMD is proposed. The first improved step (FI-EEMD) is to suppress the mode mixing and fundamental attenuation by injecting white noise and analytical signal with determined parameters into the target signal. The parameters of the analytical signal are selected according to the power grid conditions and signal characteristics. The second improved step (SI-EEMD) puts forward a signal reconstruction method based on the distribution of IMF energy extreme points and the distinguishing law of signal and noise to reduce the influence of noise-dominated components. The results show that the two-step improved EEMD not only has high-quality extracted fundamental with low total harmonic distortion (THD) and energy attenuation, but also has good applicability to aperiodic and nonstationary signals, which greatly improve the harmonic detection accuracy of APF.