Active Filter Applications Research Articles

The application of active filters supported by Pulse Width Modulated Inverters in the harmonic simulation of the high power electric traction

The paper shows the present results of a long term research work. The authors are working on the modelling of active filtering of harmonics caused by the railways. To simulate the harmonic penetration and filtering effects of the power electric traction the combination of frequency and time dependent model should be used. This novel method, called double domain simulation is improving the accuracy of the frequency domain simulation. To calculate the sophisticated model of the electric locomotive and active harmonic filter as a non-linear load a time dependent model must be used. The traction supply system together with the equivalent supply network impedance could be calculated in frequency domain. An iteration algorithm is developed converting the variables in every iteration step between the time and frequency domain.

Bi-Directional Power Flow Rapid Charging System Using a Carrier Wave Modulated Self-Commutated Voltage Source Converter for Electric Vehicle

This paper examines a high-performance battery charger for electric vehicles (EVs). Active power line filtering capabilities in the battery charger can be used to develop a fast-charging infrastructure that is advantageous for EV users as well as power distributors. This article discusses battery charger modeling and design difficulties in depth using a carrier wave modulated self-commutated voltage source converter architecture. A full study of the controller's features is also provided using model-based controller synthesis. The battery charger's active filtering performance is emphasized. In active filter applications, the model-based control system's intrinsic phase deviation and sensitivity to system factors decrease the active filter's performance, which is disclosed in this study. Based on numerous integrators in diverse reference frames, we provide an improved control structure for active filters to offset the model-based controller's degradation. The suggested controller demonstrates minimal sensitivity to system factors and fully compensates for the intrinsic phase deviation, as shown both theoretically and empirically. The suggested active filter controller has outstanding steady-state conditioning performance.

Development of Hybrid Energy Storage System Testbed with Instantaneous Discharge Controller for Shunt Active Filter Application

The high penetration of renewable energy sources has necessitated the use of more energy-storage devices in Smartgrids. The proposed work addresses the development and implementation of an Instantaneous Discharge Controller (IDC) for a hybrid energy storage system. The discharge control algorithm manages the discharge of the battery and supercapacitor and protects the battery from transient currents. Hybrid energy storage systems (HESSs) are well known for providing ideal attributes such as high-power density and high-energy density for many application areas, including electric vehicles and renewable energy-supported microgrids. However, the application of HESSs for supporting shunt active filters and protecting low power density storage systems from fast variations in load has not been proposed yet. In this context, a hybrid energy storage system (HESS) is proposed here to eliminate harmonics and to support the grid by providing real and reactive power supervened by varying load conditions. This paper proffers an innovative controller for a shunt active filter unified with an HESS to effectively manage storage devices for a microgrid connected to a grid.

Effective Harmonic Cancellation Technique for a Three-Phase Four-Wire System

An excess non-linear and unbalanced load application increases the power quality (PQ) problem by injecting harmonic current. The avoidance of neutral current control creates additional PQ problems due to excess circulating current in modern 3φ4W applications. Therefore, this manuscript suggests improved αβ transform-based voltage and current control approaches for both 3φ3W and 3φ4W shunt active filter (SAF) applications. In the proposed approach, a novel combined voltage and current (NCVC) control approach is presented for modern 3φ3W systems by using voltage and closed-loop current controllers. However, due to the absence of a neutral current, the NCVC is not sufficient for 3φ4W system application. Therefore, by considering the current reference parameter generated from the NCVC, a novel harmonic compensation technique (NHCT) is proposed with proper mathematical expressions for the 3φ4W application. To show the importance of NHCT over traditional P-Q-R control, the developed MATLAB/Simulink model is tested by using different 1φ and 3φ nonlinear/unbalanced load conditions. The comparative results indicate that, by using NHCT, the 3φ4W system contains a lesser total harmonic distortion (THD) and harmonic mitigation ratio (HMR), less ripple frequency, an improved power factor, a lesser neutral current, and a balanced active/reactive power condition. From the above comparative analysis results, it is found that the overall improvement percentage is 66.78%. The above findings justify the significance of the NCVC and NHCT approach during both unbalanced and non-linear load-based 3φ4W applications.

Performance improvement of a system level harmonic using a harmonic power flow controller

Penetration of harmonics from downstream low voltage networks and resonance phenomenon has caused the level of harmonics to increase in transmission networks. Compensation of these harmonics at high voltage levels is neither recommended nor cost effective. This is due to the fact that there is no single large non-linear load which is causing these harmonics, yet filtering at low voltage non-linear load sites cannot completely compensate the harmonics and the remaining harmonic at standard levels still flow into the upstream networks. The idea of controlling harmonics at a medium/high voltage level caused by the remaining harmonics flown from low voltage networks and possibly amplified by resonance conditions with the use of series active power filters has been proposed by the authors in a published work. Since, this application of a series active filter was new, it was preferred to assign a new name for such device, i.e. harmonic power flow controller or simply HPFC. This work looks into the control strategies applicable to a HPFC in more details. The shortcomings of the previous methods are now removed resulting in better performance of a HPFC.

Автоматизированная система управления электроприводами с интеграцией программируемых реле и активных фильтров

This paper discusses relevant challenges in upgrade of control systems and reviews possible applications of new programmable relays OVEN PR10 for non-stop Ethernet data transmission. It also discusses integration of active power filters in feeding circuits of electric drives with upgraded automatic control systems. The study analyses the applications of active filters and suggests a testing system that consists of electric compressor drives and automated multi-channel control system with integrated active filters. The tests performed under this study have shown that automatic systems work more efficiently if they are fed by high-quality loading current from their electric drives and are governed by OVEN PLC110 programmable logic controllers. This paper also describes a case study: laboratory experiment on integrating active power filter for interharmonic current components with multi-channel drive control system based on cutting-edge programmable relay OVEN PR103. The results of this study could be useful for the upgrade of Russian fishing fleet, as well as for design and development of innovative ships.

A Comprehensive Survey on Different Control Strategies and Applications of Active Power Filters for Power Quality Improvement

Power quality (PQ) has become an important topic in today’s power system scenario. PQ issues are raised not only in normal three-phase systems but also with the incorporation of different distributed generations (DGs), including renewable energy sources, storage systems, and other systems like diesel generators, fuel cells, etc. The prevalence of these issues comes from the non-linear features and rapid changing of power electronics devices, such as switch-mode converters for adjustable speed drives and diode or thyristor rectifiers. The wide use of these fast switching devices in the utility system leads to an increase in disturbances associated with harmonics and reactive power. The occurrence of PQ disturbances in turn creates several unwanted effects on the utility system. Therefore, many researchers are working on the enhancement of PQ using different custom power devices (CPDs). In this work, the authors highlight the significance of the PQ in the utility network, its effect, and its solution, using different CPDs, such as passive, active, and hybrid filters. Further, the authors point out several compensation strategies, including reference signal generation and gating signal strategies. In addition, this paper also presents the role of the active power filter (APF) in different DG systems. Some technical and economic considerations and future developments are also discussed in this literature. For easy reference, a volume of journals of more than 140 publications on this particular subject is reported. The effectiveness of this research work will boost researchers’ ability to select proper control methodology and compensation strategy for various applications of APFs for improving PQ.

Application of Active Filters in Power Systems

Application of Active Filters in Power Systems

A New Quasi Open Loop Synchronization Technique for Grid-Connected Applications

Abstract This paper presents an effective quasi open-loop (QOLS) synchronization technique for grid -connected power converters that is organized in two different blocks. The first block is a new flexible technique for extracting the positive and negative sequence voltage under unbalanced and distorted conditions. It is a decoupled double self-tuning filter (DD-STF) or multiple self-tuning filters (M-STF) according to the conditions. The main advantages of this technique are its simple structure and the fact of being able to work under highly distorted conditions. Each harmonic is separately treated and this allows for selective compensation in active filter applications. The second block is the frequency detector; we propose a neural approach based on an ADALINE for online adaptation of the cut-off frequency of the DD-STF and M-STF considering a possible variation in the main frequency. The main advantage of this method is its immunity to the voltage signal amplitude and phase. In order to improve the performance of the frequency estimation under distorted source voltage, a pre-filtering stage is introduced. Experimental tests validate the proposed method and illustrate all its interesting features. Results show high performance and robustness of the method under low voltage ride through.

Harmonics Analysis of Input Current of 3-Phase PWM Rectifier

Rectifier is a non-linier load that causes harmonic distortion in the power system. Pulse-width modulation (PWM) method is an effective method in pressing the magnitude of harmonics in a rectifier application, it provides an almost sinusoidal input current. However, the variation of loads that supplied by a rectifier cause the harmonics that arise can still beyond the applicable standard. The amount of harmonics in the operating range of a rectifier need to be identified to determine the filter on the input side. In this research article, 3-phase PWM rectifier was designed with hysteresis current control technique using PSCAD software simulation. Harmonic compensation was carried out by applying an active filter based on P-Q theory to reduce the harmonic distortion that occurs in the input current, thus giving a low total harmonic distortion (THD) value. Based on the simulation, 3-phase PWM rectifier operation starting at a power level of 150 kW, giving a THD value above 5-10% by the increasing the amount of load supplied by the rectifier. The application of active filter based on the P-Q theory is able to compensate harmonics in the input current wave with a THD value below 5% in the rectifier operating range.

Ultra-Wide Bandwidth Fully Differential CMOS Opamp with a Novel Bandwidth Extension Technique for SoC Active Filter Applications

An ultra-wide bandwidth fully differential two-stage 65[Formula: see text]nm CMOS operational amplifier (Opamp) is presented, which uses a novel bandwidth extension technique called “pole duplication”. This technique is based on relocating the dominant pole with the same location with a non-dominant pole and adjusting 3-dB frequency and stability with a compensation network. Simulation results show that the proposed Opamp has 103[Formula: see text]MHz 3-dB bandwidth with a 2[Formula: see text]pF load capacitor. It consumes 9[Formula: see text]mA current from 1.2-V supply. Transition frequency of 2.4[Formula: see text]GHz and a gain of 29[Formula: see text]dB is accomplished. A 2[Formula: see text]pF load capacitance can be driven at a phase margin of [Formula: see text]. The suggested pole duplication technique is used to achieve higher 3-dB cut-off frequencies by adjusting the load capacitor. Fully differential two-stage Opamp is presented, which uses a novel bandwidth extension technique, is suitable for SoC active filter applications with 40[Formula: see text][Formula: see text]m layout area and ultra-wide 3-dB bandwidth.

Performing reactive power compensation of three-phase induction motor by using parallel active power filter

Nowadays, the problem of power quality increases day by day. Harmonic current and reactive power are the important factors disturbing the power quality. The induction motors draw both harmonic current and reactive power from the grid. Reactive power and harmonic current lead to heat losses and decrease in the efficiency of the transmission lines. Passive and active filter applications have been used to solve these problems. There are some disadvantages of passive filters. Large physical dimensions and resonance with load can be shown as examples for these disadvantages. Therefore, the application areas of Active Power Filter (APF) are rapidly developing due to the fact that they can be applied together with harmonic and reactive power compensation as appropriate control methods. This paper proposes a MATLAB/Simulink simulation to perform power factor correction and reactive power compensation of three-phase induction motor by using three-phase Parallel Active Power Filter (PAPF). In order to generate PAPF’s reference currents the Sine Multiplication Technique (SMT) is used. Simulation studies are presented to be able to assess the performances under different motor operating conditions. The proposed hysteresis controller based PAPF filter makes the power factor up to 1 and the reactive power compensation of the three-phase induction motor.

The assesement of the shunt active filter efficiency under varied power supply source and load parameters

The results of theoretical and experimental studies on the problems of effective application of shunt active filters for power quality improvement and electromagnetic compatibility ensuring were presented in this article. Based on the different theories and methods, the most effective and well-studied control algorithms of shunt active filters were determined and analyzed to ensure their effective application in distributed generation systems and combined power supply systems. Mathematical and computer simulation models of shunt active filters with different control algorithms in distributed generation systems and combined power supply systems were developed. According to the results of mathematical modeling and computer simulation, the dependences were detected, reflecting the influences of internal and external parameters on the factors, determining the efficiency of the correction of power quality indicators. The range of permissible changes in the parameters of shunt active filters by saving the required efficiency level of power quality correction was detected under varied power supply system characteristics, load parameters and also in hybrid structures. The adaptive algorithm of the shunt active filter functioning under varied application conditions for automated power quality improvement is developed on the basis

Performance of a granular activated carbon biologically active filter (GAC-BAF) for removing microcystin-LR (MC-LR) from eutrophic water

Abstract Microcystin-LR (MC-LR) removals linked with empty bed contact time (EBCT), temperature and backwash strategies are important for biologically active filter (BAF) application but remain not entirely clear. In addition, there is still a lack of understanding about the bio-regeneration of MC-LR adsorption capacity in a BAF. This study examined MC-LR removals by a granular activated carbon-biologically active filter (GAC-BAF) as a function of EBCT, temperature, and backwash strategies. Results demonstrated that the optimum EBCT (1.2 h for this study) likely depended upon an optimum superficial velocity as well as the GAC column height. A superficial velocity not greater than 0.5 m/h was deemed appropriate according to this research. The MC-LR removals achieved at the optimum EBCT reached 54.8%–72.0%. A higher temperature resulted in a greater MC-LR removal; adsorption might contribute to effective MC-LR removal by the GAC-BAF at a lower temperature. A strategy (Air + air-water + water) was suggested as an optimal backwash strategy for GAC-BAFs in terms of MC-LR removal. A comparison of the effectiveness of the experimental GAC-BAF in continuous and discontinuous operations on MC-LR removals was conducted, from which indirect evidence for bio-regeneration of MC-LR adsorption capacity of the GAC was obtained.

Power Capability Boundaries for an Inverter Providing Multiple Grid Support Services

It is getting more common every day to install inverters that offer several grid support services in parallel. As these services are provided, a simultaneous need arises to know the combined limit of the inverter for those services. In the present paper, operational limits are addressed based on a utility scale for a real inverter scenario with an energy storage system (ESS) (1.5 MW). The paper begins by explaining how active and reactive power limits are calculated, illustrating the PQ maps depending on the converter rated current and voltage. Then, the effect of the negative sequence injection, the phase shift of compensated harmonics and the transformer de-rating are introduced step-by-step. Finally, inverter limits for active filter applications are summarized, to finally estimate active and reactive power limits along with the harmonic current injection for some example cases. The results show that while the phase shift of the injected negative sequence has a significant effect in the available inverter current, this is not the case for the phase shift of injected harmonics. However, the amplitude of the injected negative sequence and harmonics will directly impact the power capabilities of the inverter and therefore, depending on the grid-side voltage, it might be interesting to design an output transformer with a different de-rating factor to increase the power capabilities.

Harmonic Reduction Using Shunt Active Filter for Electrical Installation

This paper presents harmonic reduction using an active shunt filter for hospital building electrical installation. Generally, harmonic installation in electric power systems is caused by non-linear electrical loads, especially the ones containing coils, such as air conditioners, pump machines, fans, and others. It might cause excessive heat in a distribution transformer which supplies an electrical installation in a multi-story building. In this regard, the heat is a power loss and has the potential to shorten the life of a distribution transformer, and therefore, efforts are needed to reduce harmonics. The use of active filters is one of the most effective strategies for reducing harmonics. In this study, a shunt active filter application in the electrical installation of a hospital building was carried out. The results showed the filter reduced harmonic currents significantly, to the extent that the harmonic threshold was still under the IEEE standard.

An Efficient Shunt Active Filter for Harmonic Reduction in Hospital Building Electrical Installation

This paper proposes an efficient shunt active filter for harmonic reduction in hospital building electrical installation. Harmonic installation in distribution system is caused by non-linear electrical loads, especially those containing coils, such as air conditioners, pump machines, fans, and others. Harmonic can cause excessive heat in a distribution transformer that supplies an electrical installation in a multi-storey building. This heat is a power loss and has the potential to shorten the life of a distribution transformer, so that efforts are needed to reduce harmonics. One effective method to reduce harmonics is to use active filters. In this study, a shunt active filter application in the electrical installation of a hospital building was carried out. The results showed that the filter was able to reduce harmonic currents significantly, so that the harmonic threshold was still in accordance with the IEEE standard.

An active inductor employing a new four terminal floating nullor transconductance amplifier (FTFNTA)

ABSTRACTIn this scientific study, a new analog active building block named as four terminal floating nullor transconductance amplifier (FTFNTA) is implemented. The FTFNTA design offers a combined essence of both traditional four terminal floating nullor (FTFN) and an operational transconductance amplifier (OTA). The FTFNTA design is extended for the design of a lossless floating and grounded inductor simulator with few passive components. In addition, the performance and usefulness of the proposed inductor topology are also expanded for active filter applications: higher-order Butterworth high-pass filter and current mode multifunction filter. The functionality of the CMOS-based FTFNTA is integrated with a 0.18 µm Taiwan Semiconductor Manufacturing Company (TSMC) CMOS technology. Moreover, the FTFNTA is also realised using the current feedback operational amplifier (CFOA/AD844) and OTA (OTA/CA3080) of a commercially available IC to test the viability of the proposed inductor design. Finally, an application based on the inductor topology and its impedance characteristics are well analysed via PSPICE simulation.

The assessment of the series active filter efficiency in power supply systems of oil production enterprises

This paper deals with the problem of the efficient application of the series active filter in conditions of power supply systems of oil production enterprises with non-linear load and voltage dips. The mathematical model of the power supply system of oil production enterprise with the connected series active filter is developed. The control system for the series active filter with usage of the phase transformations, symmetrical components and frequency-controlled pulse-width modulation of IGBT control pulses is developed and proved. Based on the modelling results, the analysis of the efficiency of power quality indicators’ correction by means of the series active filter is carried out. The dependence of the voltage total harmonic distortion factor from the rated power of the output transformer of the series active filter is obtained.

Calculation of energy-saving effect from the use of parallel active filters in a three-phase fourwire power supply system with increasing the averaging interval of the measured values

he apparent power of the three-phase four-wire supply system was decomposed into quadratic components under conditions of symmetric sinusoidal phase voltages. It was shown that the power factor for this mode is a product of the shift and asymmetry coefficients, the values of which are determined through the parameters of the symmetrical components of phase voltages and linear currents. The general formulas for calculating of the energy-saving effect from the application of shunt active filters in three-phase four-wire power system for the averaging the load power both on the network period and at any time interval were obtained. It was shown that in a power supply system with a constant in time nonlinear load the gain in the power losses when using shunt active filters is inversely proportional to the square of the power factor determined at the mains voltage period. The improved control law for the shunt active filter of a three-phase four-wire power supply system was proposed, which is distinguished by the increasing of the measured quantities averaging interval. It is shown for the first time that under conditions of stable phase voltage with the increasing of the averaging interval up to the period of the symmetrical load change, the gain coefficient of the power losses increases in comparison with the averaging at the mains voltage period in accordance with the value called the irregular energy consumption coefficient. The values of the irregular energy consumption coefficient for typical curves of the active power changing were obtained. In the case of a rectangular changing of the active power curve, the irregular energy consumption coefficient is determined by two parameters: the growth rate and the duty cycle. Its maximum meaning reaches a value of 2 in the case where the maximum power level is twice the average and the minimum level is zero. For periodic curves of active power, which are approximated by piecewise sinusoidal and piecewise linear dependencies, the irregular energy consumption coefficient is determined by one growth coefficient only regardless of the value of the duty cycle, reaching the maximum values of 3/2 and 4/3, respectively.Ref. 10, Fig. 2.