Active Filtering Method Research Articles

An Improved Control Method of DC Voltage for Series Hybrid Active Power Filter

DC voltage is one of the important parameters of active power filters. Since the series hybrid active power filter does not withstand the fundamental voltage, it cannot absorb energy from the power grid, making it too difficult to control its DC voltage. In order to solve the DC voltage control problem, an improved control method for the series hybrid active power filter with magnetic flux compensation is proposed in this paper. In this improved method, the fundamental magnetic flux compensation coefficient is equal to 1, meeting the condition of fundamental magnetic flux compensation. This improved method does not rely on the precise detection and phase-locking of the fundamental voltage at the port of the series transformer. A phase-fixed active current component is generated directly by the inverter, enabling the active power filter (APF) to absorb active power from the power grid. Consequently, the active power absorbed by the APF from the power grid has a linear relationship with the active current component. Both simulation and experimentation verified the correctness and effectiveness of this proposed method.

A reference current control strategy based on Sogi and FBD method for shunt active power filter

A reference current control strategy based on Sogi and FBD method for shunt active power filter

A developed DQ control method for shunt active power filter to improve power quality in transformers.

Power transformers are the most important component in power system. Exposing these transformers to the harmonic distortions causes additional heat losses, insulation stress, decrease in lifetime of insulation, and reduced power factor with decrease in efficiency of the system. The lifespan of distribution transformers is influenced by the fragility of power quality in power networks. Harmonic mitigation filters with robust control technique are required to reduce the harmonic effects on power transformer. Traditionally, synchronous reference frame (DQ) is employed to control the shunt active power filter (APF) for mitigation of harmonics in power transformers. DQ control of Shunt APF lacks merits of fast response, delayed operation due to phased lock loop under abnormal grid conditions leading to insufficient harmonic elimination. A developed DQ method based on detecting the positive and negative sequence components is proposed to precisely control the shunt APF for reliable operation of power transformer. This detection technique improves the response time, mitigate the harmonics effecting the operation of transformer and overall power factor. The proposed control system is evaluated under different abnormal operating scenarios and compared with traditional DQ method. The results and analysis confirm the efficacy of the developed DQ method in improving the power transformer performance.

Power quality improvement by using photovoltaic based shunt active harmonic filter with Z-source inverter converter

Introduction. The major source of energy for a long time has been fossil fuels, however this has its drawbacks because of their scarcity, exhaustibility, and impossibility of reusing them. Presently, a shunt active harmonic filter-equipped two-stage solar photovoltaic system is showing off its performance shunt active harmonic filter. The global power system has been impacted by current harmonics during the most modern industrial revolution. Novelty. The proposed work is innovative, by adopting the hysteresis modulation mode with Z-source inverter to enhance the performance of the system. Furthermore, the shunt active harmonic filter also get assists in this system for better improvement in the quality of power. Purpose. By incorporating an impedance source inverter and a photovoltaic shunt active harmonic filter methods, harmonic issues are mitigated. Methods. Load compensation is one of the services that the shunt active harmonic filter offers, in addition to harmonic compensation, power factor correction, and many other functions. The current pulse width modulation voltage source inverter method is more expensive, requires two converters owing to its two-stage conversion, has significant switching losses, and has a low rate of the reaction. The new model, in which the voltage source inverter is substituted out for a Z-source inverter converter, has been developed in order to address the problems of the existing system. Results. Rather than using a hybrid of DC-DC and DC-AC converters, the suggested system uses a shunt active harmonic filter that is powered by a photovoltaic source using a Z-source inverter. Utilizing Z-source inverter helps to address the present issues with conventional configurations. Practical value. By using software MATLAB/Simulink, this photovoltaic shunt active harmonic filter technique is analyzed. Shunt active harmonic filter, which produces compensatory current from the reference current obtained as from main supply, is powered by the photovoltaic array.

An improved robust model predictive and repetitive combined control for three-phase four-leg active power filters with fixed switching frequency

An improved robust model predictive control (MPC) method for a three-phase four-leg active power filter (APF) is proposed in this paper. First, the decoupling model in abc coordinates of the four-leg APF is derived, and then an optimal control law is also deduced based on the calculation of the partial derivation of the cost function, which is composed of the current tracking error and control quantity with a weighted coefficient. In addition, repetitive control (RC) is introduced to eliminate the prediction error inherent in the model. Finally, the influence of control parameters on the stability of the system is analyzed by the Jury stability criterion, the performance of the proposed method has also been investigated with the perturbations of the filter inductor parameters, and strong robustness, fixed switching frequency and rapid dynamic response of the whole system can be obtained. Simulation and experimental results show the effectiveness and feasibility of the proposed method.

A heat dissipation design strategy based on computational fluid dynamics analysis method for shunt active power filter

Aiming at the heat dissipation design problem of shunt active power filter, this paper proposes a computational fluid dynamics (CFD) simulation method of module flow–heat transfer coupling under forced air cooling. The power filter has carried out a detailed heat generation analysis, and given the analysis and simulation results, the heat dissipation system of the parallel active power filter is designed. The experimental results of the compensation performance prove that the designed modular system has an excellent dynamic, steady-state performance, and temperature rise. The experimental results are consistent with the simulation analysis, which demonstrates the effectiveness of the heat dissipation design of the parallel active power filter module proposed in this paper.

ПОВЫШЕНИЕ КОЭФФИЦИЕНТА МОЩНОСТИ И УМЕНЬШЕНИЕ ГАРМОНИК ТОКА ИСТОЧНИКА ПИТАНИЯ В СИСТЕМЕ ЭЛЕКТРОПРИВОДА КОНВЕЙЕР

Relevance Currently, frequency converters with diode rectifiers are very often used in conveyor drive systems. However, frequency converters generate current harmonics, adversely affecting the quality of the network and the durability of electrical equipment. In the electric drive system, the induction motor consumes the reactive power of the source, which causes losses in the network and reduces the power factor at the input of the converter. Therefore, for the electric drive system, it is necessary to analyze methods for improving the power factor and reducing harmonic distortion of the current in the network. The reactor frequency converter has a simple structure but does not have high efficiency. A frequency converter with a multi-pulse rectifier will use multiple rectifier circuits in combination with a transformer to eliminate high order harmonics. The reactor frequency converter has a simple structure but does not have high efficiency. A frequency converter with a multi-pulse rectifier will use multiple rectifier circuits in combination with a transformer to eliminate high order harmonics. The active filter method will produce current waves of the same amplitude but opposite phase angle to the harmonics generated by the load, which eliminates most high-order harmonics and can compensate for reactive power. Aim of research Improving the energy efficiency of the conveyor electric drive with minimizing its impact on the quality of the electric power of the quarry network through the use of active rectifiers with a direct power control system in multi-inverter frequency converters. Research methods In this study, the following methods were used: the study of scientific literature, computer simulation performed in the MatLab software package. Results The frequency converters use active rectifiers with direct control of active and reactive power, the power factor is close to unity, and the energy exchange occurs in two directions between the motor and the network. The article compares the effectiveness of methods when considering a system of the frequency-controlled electric drive of conveyors.

Harmonics Mitigation Filter for High-Power Applications

This research work proposes a cost-effective Hybrid Active Harmonic Filter (HAHF) method to mitigate current harmonics in an industrial or commercial power network. The proposed HAHF is based on a Silicon-Controlled Rectifier with an Electronic Inductor (SCR-EI) topology with a reduced number of fully active switches and a better harmonic performance. A new shifted-pulse current modulation method is proposed to cancel harmonics caused by other converters. A Particle Swarm Optimisation (PSO) algorithm is implemented to optimise the modulation parameters and minimise the total harmonics. A lab prototype is implemented in the laboratory to validate the proposed mathematical method and simulation results.

An Effective Harmonic Suppression Method Based on Linear Active Disturbance Rejection Control for Copper Electrowinning Rectifier

Because the harmonics in the production process of copper electrowinning have an important impact on the electrical energy consumption, it is necessary to suppress the harmonics effectively. In this paper, a copper electrowinning rectifier with double inverse star circuit is selected as a study object in which a large number of harmonics mainly including the 5th, 7th, 11th, and 13th harmonics are generated and injected back into the power grid. The total harmonic distortion rate of the power grid is up to 29.19% before filtering. Therefore, a method combining the induction filtering method and the active filtering method is proposed to carry out comprehensive filtering. Simulation results demonstrate that the total harmonic distortion rate of the system decreases to 4.20%, which indicates that the proposed method can track the corresponding changes of harmonics when the load changes in real time and filter them out. In order to ensure and improve the effect of active filter, a current harmonic tracking control method based on linear active disturbance rejection control is proposed. Simulation results show that the total harmonic distortion rate decreases to 3.34%, which is also lower than that of hysteresis control. Compared with the conventional single filtering method, the new filtering method combining induction filtering with active filtering based on linear active disturbance rejection control in the copper electrowinning rectifier has obvious advantages.

A modified indirect extraction method for a single-phase shunt active power filter with smaller DC-link capacitor size

Indirect extraction method is the most common method to control the single-phase active power filters (APFs) due to its simple structure. The main drawback of this extraction method is its performance dependency on the quality of the DC-link voltage. Selecting the high capacity of the DC-link capacitor leads to the high cost and size of APF, weak dynamic response and low-even-order harmonic components on the DC-link voltage. The low capacity of the DC-link capacitor decreases the cost and size of APF, decreases the sub-harmonics and inter-harmonics of the DC-link voltage, improves the dynamic response, and increases the even-order voltage harmonics. This paper proposes a new extraction method to improve the performance of the conventional indirect extraction method. The proposed method uses a small size of capacitor to achieve the aforementioned advantages. The even-order voltage harmonics are eliminated by the single-frequency-decoupled (SFD) scheme. For implementation of the SFD scheme, the proposed method uses proportional-resonant (PR) controllers, and second order generation integrator-frequency locked loop (SOGI-FLL). The effectiveness of the proposed extraction method is verified by the simulation and experiment.

A Novel Starting Impulse Suppression Method for Active Power Filter Based on Slowly Rising Curve

With the widespread application of power electronic equipment in the power grid, the harmonic problem of the power grid becomes more pronounced, reducing the efficiency of power production, transmission, and utilization, and interfering with the normal operation of the power grid. Based on the requirements of harmonic suppression and power system protection, a shunt active power filter (SAPF) is proposed as an effective harmonic suppression method. However, there are problems with impulse current and impulse voltage in the starting process of SAPF. Impulse current and impulse voltage cause the power grid and switchgear to bear greater current stress and voltage stress, which seriously affect the security and reliability of the power grid and may damage the switchgear. To effectively solve the problem of impulse current and impulse voltage, the starting process of SAPF is divided into the uncontrolled rectification stage and the transition stage. The mathematical model of the DC side of APF is established. The causes of impulse current and impulse voltage in the uncontrolled rectifier and transition phases are analyzed. By introducing voltage square, a new starting impulse suppression strategy of active power filter based on the slow rising curve is proposed, fundamentally solving the problems of impulse current and impulse voltage. Simulation results verify the effectiveness and feasibility of this method.

Vortex search algorithm for designing hybrid active power filter

<p>This paper proposes a new multi-objective optimization design method for Hybrid Active Power Filter based on the Vortex Search algorithm. The Vortex Search algorithm belongs to the Single-Solution Based algorithm class of Metaheuristics algorithm. This design method has the advantage of fast execution time, high convergence speed and prevent local trap problems. The achieved results are multi-objective, such as minimum total harmonic distortion of the supply current and source voltage and satisfy many constraints such as system stability, resonance conditions of branches and limits of the parameters. Compared with the traditional design method, simulation results have proved that: the proposed design method is given with better results in minimizing total harmonic distortion of the supply current and source voltage.</p>

Adaptive Backstepping Fractional Fuzzy Sliding Mode Control of Active Power Filter

An adaptive fractional-order fuzzy control method for a three-phase active power filter (APF) using a backstepping and sliding mode controller is developed for the purpose of compensating harmonic current and stabilizing the DC voltage quickly. The dynamic model of APF is changed to an analogical cascade system for the convenience of the backstepping strategy. Then a fractional-order sliding mode surface is designed and a fuzzy controller is proposed to approximate the unknown term in the controller, where parameters can be adjusted online. The simulation experiments are conducted and investigated using MATLAB/SIMULINK software package to verify the advantage of the proposed controller. Furthermore, the comparison study between the fractional-order controller and integer-order one is also conducted in order to demonstrate the better performance of the proposed controller in total harmonic distortion (THD), a significant index to evaluate the current quality in the smart grid.

An Improved Variable Step Size LMS Harmonic Current Detection Method for Active Power Filter

With the development of adaptive filter theory, many adaptive filtering techniques are used for harmonic current detection, and achieve some good results. But it is difficult to detect harmonic current in the low signal-to-noise ratio (SNR) condition when using conventional algorithms. Based on adaptive noise cancellation theory, this paper proposed a modify variable step size least mean square (MVSS-LMS) algorithm for harmonic current detection. The step size of the proposed method is controlled by the improved generic Sigmoid function relationship with the error signal. The MVSS-LMS has fast convergence and good tracking performance of fundamental and harmonic components from distorted signals, and simulation results prove the algorithm having a good feature.

Current Reference Control for Shunt Active Power Filters Under Unbalanced and Distorted Supply Voltage Conditions

This paper proposes a current reference control method for shunt active power filter under unbalanced and distorted supply voltage conditions. The method uses the Kalman filter and the symmetrical component method to obtain the fundamental sequence component of the supply voltage. The Fryze-Buchholz-Dpenbrock method is used to decompose the load current under the reference of the fundamental positive-sequence voltage to obtain the reference value of the compensation current. The method is characterized without need of coordinate transformation, simple calculation, and clear physical meaning. The harmonic current, reactive current and negative sequence current can be compensated at the same time even under the condition of unbalanced supply voltage. The proposed method is compared with the traditional method under various experimental conditions to prove the validity and accuracy of the proposed method. The results show that the proposed method has wider applicability.

Frequency Adaptive Prefiltering Stage for Differentiation-Based Control of Shunt Active Filter Under Polluted Grid Conditions

A differentiation-based control method for a shunt active power filter is used in this paper for functioning in the presence of grid voltages distortion and imbalances. To enable the fast and accurate estimation of the variables in the presence of unbalancing or distortion in the grid voltages, a prefiltering scheme is considered based on the dual second-order generalized integrator approach. The signal recomposition performed by the prefilter isolates the harmonics from the voltage and current waveforms, and the differentiator frequency locked loop (dFLL) is able to estimate the frequency of the waveforms, which is used as a feedback for the prefilter, thus making the system frequency adaptive. The control algorithm is validated with both simulation studies. The prototype of an active power filter is developed, which carried out current compensation robustly, demonstrating the speed and accuracy of the system even under distorted grid conditions by achieved total harmonic distortions (THDs) of the grid currents within limits (less than 5%) as dictated by IEEE Std. 519-2014.

Enhanced Instantaneous Power Theory Decomposition for Power Quality Smart Converter Applications

Power theories are advancing signal decomposition approaches used for electrical power signal analysis. Currently, they are key tools for designing reliable and efficient power electronic interface controllers. Due to the inherent uncertainty in the power generation within new technology of distributed generation units (such as renewable-based microgrids), most of these theories are not directly applicable in the era of new power engineering systems. Furthermore, the traditional formulations are not appropriate once we face the nonlinearity in the consumption along a weak grid that may not maintain steady voltage or frequency. Therefore, a new signal decomposition method with a higher level of selectivity must be developed to modify the traditional power theories and improve the control strategies from a design viewpoint. This paper describes a novel formulation of an instantaneous power theory, enhanced instantaneous power theory (EIPT), for unbalanced and nonlinear three-phase power systems. EIPT establishes a proper decomposition of current components for cases of balanced, unbalanced, and distorted voltage sources. In addition to mathematical analysis, this research provides comprehensive simulations under different loads and source conditions, which supports the performance of the EIPT in the active filtering methods. Moreover, the performance of the proposed method is compared with the state-of-the-art approach widely known as the conservative power theory. Our results indicate that this new comprehensive approach is helpful in optimizing control strategies for power electronic interfaces and power quality compensators.

Optimal design of shunt active power filter for power quality enhancement using predator-prey based firefly optimization

The nonlinear behavior of present day power electronic based equipments generates harmonics that lead to overheating, efficiency reduction and malfunctioning of the utility equipments. Shunt active power filters (SAPF), comprising of a three phase voltage source inverter (VSI) and a dc capacitor, are commonly used to eliminate the harmonics at source side. The design of these filters is very important in obtaining satisfactory performances. The classical design methods and the tuning of controller gain parameters may not yield optimal performances. This paper formulates the design of SAPF as an optimization problem with an objective of minimizing the total harmonic distortion (THD) and solves it using predator-prey based firefly optimization (PPFO). The PPFO inherits the features of predator-prey concept and firefly optimization (FO) and helps to get away from the suboptimal traps, thereby ensuring global optimal design. The paper also includes the simulation results of a few test cases representing different types of harmonic loads and illustrates the superior performances of the proposed design philosophy. • An optimal design method for shunt active power filter is proposed. • It attempts to minimize the harmonics in source current. • It employs predator-prey based firefly optimization. • The performance is exhibited with six test cases.

Improved adaptive notch filter-based active damping method for shunt active power filter with LCL-filter

The LCL-filter has been recently used with grid-connected converters to mitigate switching ripple harmonics. The LCL-filter presents a better attenuation performance for switching ripple harmonics in comparison with L- and LC-type filters. However, the application of LCL-filter has two basic constraints on the circuit design and the resonance problem. These constraints can be effortlessly overcome for grid-connected converters which operate on the utility fundamental frequency. On the other hand, these constraints become a challenging issue when the LCL-filter is used with shunt active power filter (SAPF) because of the wide operation frequency bandwidth of SAPF. This wide operation bandwidth of SAPF causes a narrow bandwidth for the selection of LCL-filter cutoff frequency and the resonance damping control. In this paper, the application constraints of LCL-filter are discussed and the LCL-filter design is provided for SAPF. In addition, an adaptive notch filter-based single-loop active damping method is developed considering the wide operation bandwidth of SAPF. The proposed method consists of a grid impedance estimation algorithm in order to update notch filter parameters adaptively against grid impedance variations. By the help of the single-loop active damping strategy, the proposed controller does not require any additional sensor for the current measurement of LCL-filter capacitor to damp resonance currents. The stability analysis of proposed controller is performed through pole–zero maps. The proposed method is tested, and its performance is verified with comprehensive case studies of a 400-V 80-kVA SAPF simulation model through MATLAB/Simulink.

Multi-objective Design Method for Hybrid Active Power Filter

AbstractIn this paper, a multi-objective optimal design for transformerless hybrid active power filter (HAPF) is proposed. The interactions between the active and passive circuits is analyzed, and by taking the interactions into consideration, a three-dimensional objective problem comprising of performance, efficiency and cost of HAPF system is formulated. To deal with the multiple constraints and the strong coupling characteristics of the optimization model, a novel constraint processing mechanism based on distance measurement and adaptive penalty function is presented. In order to improve the diversity of optimal solution and the local searching ability of the particle swarm optimization (PSO) algorithm, a chaotic mutation operator based on multistage neighborhood is proposed. The simulation results show that the optimums near the ordinate origin of the three-dimension space make better tradeoff among the performance, efficiency and cost of HAPF, and the experimental results of transformerless HAPF verify the effectiveness of the method for multi-objective optimization and design.