Three level hysteresis current controller based active power filter for harmonic compensation

Various electronic circuits such as inverters, choppers, cyclo-converters, SMPS used by industrial and domestic purposes are non-linear in nature, which makes the load current to be distorted, causing undesirable effects like heating, equipment damages, EMI related problems in power system. The active power filter (APF) is the best solution for eliminating the harmonics caused by the non-linear loads. This paper presents about a three-phase four-wire active power filter for power line conditioning to improve power quality in the distribution network and implementation of a digitally controlled APF. The active power filter is implemented with PWM based current controlled voltage source inverter (VSI).The switching signals for APF are generated through proposed three-level hysteresis current controller (HCC). The shunt APF system is modeled and investigated under different unbalanced non-linear load conditions using MATLAB program. The Controller Design using Hardware Description Language (VHDL or VERILOG) becomes independent of process technology. Synchronous reference frame (SRF) is used for generation of reference current. Both PI current algorithm and HCC are written in VHDL code and implemented using FPGA platform.

The non-linear devices used in the present environment like computers, printers, lasers, smps, rectifiers etc. pollutes the power system by harmonics and reactive power. Due to the presence of harmonics in the power system a number of undesirable effects caused in the distribution network. To find the solution for this the active power filter (APF) is one of the suitable solutions, which compensates Harmonics as well as reactive power simultaneously. This paper presents a active power line conditioning system to improve the power quality in the distribution network and implementation of a digital controller using 8051 microcontroller. The active power line conditioner is implemented with Pulse Width Modulation (PWM) based current controlled voltage source inverter (VSI). The Digital Controller is designed using MCS 8051 microcontroller which becomes independent of process technology. Synchronous reference frame (SRF) is used for generation of reference current. The PI current algorithm is implemented using MATLAB platform. The shunt APF is modeled and investigated under different unbalanced non-linear load conditions in MATLAB/SIMULINK. The simulation results reveals that the active power filter is efficiently compensating the current harmonics and reactive power in the distribution network. The APF system is in compliance with the IEEE 519 and IEC 61000-3 recommended standards.

Current Control of the Isolated Self-Excited Induction Generator using Shunt Active Filter

Fryze Current Controller Based Active Power Filter

This paper present the mitigation of line current harmonics using control of shunt active power filter (SAPF). The three phase system is connected to nonlinear load which cause harmonics to affect the power system. The control of shunt active power filter is not only compensating harmonics but also compensate reactive power. Voltage source inverter(VSI) at using SAPF reference current control strategies; instantaneous real and reactive power theory (p-q theory), modified synchronous rotating reference frame theory(Modified d- q theory) with PI control and current control method at using hysteresis current control and SPWM controller. The different control technique of SAPF is based on reference current generation and current control method simulated by using MATLAB Simulink.

This paper presents the design and simulation of a single-phase shunt active power filter for harmonic and power factor compensation of multiple nonlinear loads. The system is modeled in Matlab Simulink to consist of an uncontrolled rectifier and an AC controller as the nonlinear loads, with an active filter to compensate for the harmonic current injected by the load. The active filter is based on a full-bridge single-phase inverter. The design of the active filter controller is based on time-domain method that consists of three main tasks; to identify the harmonic content and form a synchronized reference, to provide closed-loop control to force the current of the active filter to follow the reference and to regulate the capacitor DC voltage. The spectral analysis of the supply current shows the harmonics produced by the load has been successfully compensated by the active filter. The effect of varying the switching frequency on the performance of the active filter is also presented.

Now a days, because of enhancement in high speed computing elements, high voltage controlled semi-conductor devices and emergence of new power circuit topologies, the Voltage Source Converter (VSC) based Active Power Filter (APF) is finding applications for compensating harmonic currents drawn by the various loads. As the active filter consists of semi-conductor devices alone, the response time of this device is very fast and it doesn’t suffer from resonance and other stability problems as faced by the normal passive filters. The Active filters are generally used at harmonic producing loads. Among all APF’s the Shunt Active Power Filter (SAPF) is more prominent at medium/high voltage applications, and also it provides higher efficiency. SAPF in the power circuit can be used either by using the voltage-sourced PWM converter equipped with a DC capacitor or a current-sourced PWM converter equipped with a DC inductor. This paper presents an approach to determine reference compensation currents of the three-phase SAPF under distorted and/or unbalanced source voltages in steady state. It is planned to design a Synchronous Reference Frame (SRF) controller for Voltage Source Converter (VSC) based Shunt active power filter for harmonic compensation. The simulation results have been obtained by using MATLAB/ SIMULINK.

Three-phase four-wire (3P4W) electrical distribution systems are extensively utilized in commercial and industrial sectors. These electrical distribution systems are facing severe power quality issues such as current harmonics, reactive power, and load unbalancing, excessive neutral current. This paper presents the analysis, design and digital simulation of a hysteresis current controller (HCC) based active power filter (APF) to improve the power quality in a 3P4W electrical distribution system. In the present work APF is implemented with a 4-leg voltage source inverter (VSI) which is connected in shunt to the 3P4W electrical distribution system. The VSI switching signals are generated through a hysteresis current controller (HCC), which has good current tracking accuracy, unconditioned stability and easy implementation. The proposed HCC based APF compensates current harmonics, reactive power, and load unbalancing and neutral current in 3P4W electric distribution system feeding nonlinear and unbalanced loads. The performance of the HCC based APF is demonstrated using MATLAB© simulation.

This paper compares two types of current control techniques with a view to the problem of switching ripples in the supply current caused by switching of an active power filter (APF). A closed loop control scheme of a three-phase APF is implemented using a TMS320C31 DSP for direct and indirect current control techniques. A current controlled voltage source inverter (CC-VSI) is used as an APF. A three-phase diode bridge rectifier with R-L load is taken as a nonlinear load. Experimental results for both the techniques of current control are compared and the capability of the indirect current control technique towards the elimination of switching ripples is established.

41 - Active Filters

The extensive use of power electronics devices in power systems, including rectifiers and inverters, presents considerable issues regarding power quality. One problem is the creation of current and voltage harmonics, which result in load waveform distortion, voltage fluctuation, voltage drop, and equipment overheating. Harmonic current sources are prevalent in commercial, institutional, and medical establishments, encompassing computer power supplies, fluorescent lights with electronic ballasts, elevator motors, and electrical devices using switch-mode power supplies. Active power filters (APF) represent the most effective method for harmonic reduction and may be used across many applications. This study employs a digital active power filter to eliminate harmonics from the source current in a grid system characterized by non-linear demand. Nonlinear loads are essential components of every power system. The advent of power electronics has resulted in switching components constituting a substantial portion of electrical demand. These features create discontinuities in lines, exacerbating line losses and diminishing power quality and sine wave integrity. Passive filters effectively eliminate harmonics at specified frequencies within the design. Active filters, conversely, operate in accordance with the prevailing harmonics. This work develops a shunt active power filter that mitigates current harmonics generated by non-linear loads. The active filter includes a voltage source converter (VSC) that functions in conjunction with a DC coupling capacitor. The VCS delivers power at the point of common coupling (PCC). The reference current is obtained by the instantaneous power theory. The instantaneous power theory, or PQ theory, has been enhanced with the FIS control system to optimize DC voltage generation over the DC link capacitor. The fuzzy system substituting the PI controller has a 49-rule base structure organized in a 7x7 configuration for the generation of error signals. A comparative study of DC voltage and total harmonic distortions (THDs) is conducted using MATLAB software and the FFT analysis tool..

The most powerful solution to current harmonics is a shunt active power filter (SAPF). Because of its simple implementation features, the Synchronous Reference Frame (SRF) concept has been commonly used in current harmonics extraction algorithms in its controller. The traditional SRF algorithm, on the other hand, has a significant time delay due to its heavy dependency on slow numerical filters. Furthermore, the algorithm is still thought to have unnecessary features that place an undue computational burden on the controller. Active control filters are commonly used in the power system to reduce harmonics induced by nonlinear loads. The Shunt Active Power Filter (SAPF) injects a suitable compensating current at a line point known as the point of common coupling (PCC) to cancel out the line's harmonics and restore the sinusoidal existence of voltage and current waveforms. As an active filter, a three-phase current-controlled voltage source inverter (VSI) with a DC connection capacitor across it is used. Shunt active power filter (SAPF) is the best solution that minimises the harmonic problems in power systems, but how fast and how effective it is. This paper describes a detailed study about the various types of power quality disturbances and their mitigation techniques and their comparative details.

In this paper, a shunt active power filter based on fuzzy logic controller is modeled, simulated, and tested. The fundament of Instantaneous Reactive Power Algorithm is used for extracting compensated reference harmonic current. A fuzzy logic controlled shunt Active Power Filter (SAPF) Using Hysteresis Band Current (HBC) is applied to regulate the DC capacitor voltage of (SAPF) in order to improve the active filter dynamic, to ensure sinusoidal source currents and to produce a high power quality. The main goal of the proposed active filtering system is to maintain the THD well within IEEE-519 on harmonics levels. Simulation results through MATLAB/Simulink are presented and interpreted. It is demonstrated that the fuzzy logic controller improves the performance of the active power filter. The implementation of a shunt active power filter has high performance characteristics by using dSPACE system.

This study begins with a brief overview of the problem of harmonic distortion and its effect on the quality of electric power, how the active power filter mitigate this problems then investigate the effect of control circuit time delay on the performance of Active Power Filter (APF). Active filter is an electronic power system that absorbs harmonic currents in the network, generated by nonlinear loads. The nonlinear load seems the main source of harmonic distortion in the power system. A shunt active power filter with optimized PI discussed in this study. Delay times are inevitable in Digital Signal Processing (DSP) based controllers can significantly degrade the performance of active power filter. Active filter performance can be affected by the delay between the control and measurement of the output current of SAPF and load current harmonics. The proposed filter reduces harmonic distortion is within an acceptable range.

This paper presents an analysis of the modeling of reactive power compensation using renewable energy from sunlight through photovoltaic to eliminate harmonic signals in the electricity network with a three-phase active power system filter. Electric energy supply comes from three-phase electricity sources in the form of a sinusoid. Non-linear loads such as electronic devices and electrical equipment connected to the grid generate harmonics signals; can make the format of electrical energy distorted. This nonlinear load draws electric current in the form of non-sinusoid. This format increases Total Harmonic Distortion (THD), thereby worsening the performance of electrical equipment. An active power filter is a very effective method in reducing harmonics signals and increasing the quality performance of electricity. This power filter works by injecting compensation current into the grid. The energy that is injected comes from the direct current output voltage (DC) of the photovoltaic link stored in the capacitor via a Voltage Source Inverter (VSI) switch. The compensation current has the same format as the harmonics current but differs in 180°. The main parts of this power filter include the Reference Signal Generating Unit, PI Controller, VSI Switch Signal Ignition Gate Generator, Energy Storage Circuit (Battery), and Photovoltaic. Simulation modeling using Matlab Simulink Tools to reduce THD levels by IEEE 519 standards. Simulation results show a significant decrease in Total Harmonic Distortion (THD), where the grid before compensation contains THD of 29.74% and after injection of 2.25%. So this modeling is worth proposing as an active filter in a power system.