Adaptive filter based current controller for Shunt Active 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.

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

In recent years, power electronics devices have evolved, and used for varies applications. Also, this device caused the problem of power quality in electrical system. In the utility side arc furnaces, variable frequency drives (VFD), personal computer, fluorescent lamp such non-linear load produces current harmonics. For consumer and distributed side the power quality is an important issue. The active power filter which is capable for improving the power quality and reactive power compensation. In this paper the harmonics problem which is created by non-linear load is discussed. Shunt active filter is used for eliminating the harmonics from non-linear load and in the retrieval technique for controlling the current hysteresis current controller is used. In this paper for producing the reference current instantaneous reactive power (PQ) theory is used. The simulation result of shunt active filter using PQ theory is carried out using Matlab-Simulink toolbox.

This chapter explains excellent performance of shunt active power filter (SAPF) integrated with photovoltaic source, for considerable energy management, harmonic alleviation, and reactive power recompense. The solar plant produces extreme or equal power essential to the load requirement, hence the coordination with grid is complex. The PV module is designed with INC-MPPT technology, and the shunt active power filter is connected at the AC side of the inverter integrated with a nonlinear load. Here, the shunt active power filter design depends on PI controller whose gains are selected arbitrary. In the first study, the total harmonic distortion (THD) is calculated with no filter and nonlinear load. Then, THD analysis is performed with SAPF. Further to pick up the recital of shunt active power filter, a new PSO optimization technique is applied to select the proper value of PI gains R and L of nonlinear load. The simulation result depicts that the optimized shunt active filter reduces harmonics to a great extent. The results of SAPF, PSO-SAPF, APSO-SAPF, and TCPSO-SAPF are compared.

This paper presents a modeling and a nonlinear control of three-phase voltage source shunt active filter. The modeling is based on the abc/dq transformation of the AC system variables. The currents injected by the active filter are controlled in the synchronous orthogonal dq frame using a decoupled nonlinear control strategy. The reference harmonic components are extracted from the sensed nonlinear load currents by applying the synchronous reference frame method, where a three-phase thyristor bridge rectifier with R-L load is taken as the nonlinear load. The voltage level of the DC side is regulated using a linearizing feedback control. The reference current needed to maintain a regulated DC voltage is added to the current loop reference. The transfer functions of the two loops are developed and synthesized to obtain the desired stability and dynamic response. Simulation results confirm the performances considered theoretically for the shunt active filter topology.

Harmonics in the power system can be reduced and thus power quality can be improved with the use of Active power filter. In this literature, fixed switching frequency single phase shunt active filter based on sliding mode controller is modeled and analyzed using MATLAB. Control law is designed to generate both continuous and discontinuous component of the control signal. Pulse width modulated switching signals to the shunt active power filter are generated from the Control output of the sliding mode controller. DC link capacitor voltage is controlled using PI controller which gives the reference source current. Performance of single phase shunt active power filter with nonlinear and combined nonlinear and linear load is demonstrated with the help of simulation results.

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.

The distribution system's nonlinear loads cause low total harmonic distortion (THD), low distortion power factor, and localized communication interference, among other poor power quality metrics. Shunt active power filter (SAPF) capacity to function depends on the controller's ability to follow the reference signal. To manage larger systems with several inputs and outputs, it would be challenging task to design PID controllers, because excessive controller gains would need to be tuned. Also, every control loop would operate independently of one another, as if there were no interactions between the two loops. This paper proffers Model prediction control for Shunt active power filter (SAPF), which can manage systems with several inputs and outputs that may interact with one another. Luenberger observer (LO) and Proportional Integral observer (PIO) fail to estimates the actual states of SAPF to SAPF, as shown even in the presence of three unknown disturbances, i.e step, triangular and noise type. The proposed unknown input observer (UIO) in the presence of three unknown disturbances perfectly tracks the reference signal. Apart from state estimation, the proposed observer also estimates all the unknown disturbances, when compared to PIO. The results have been simulated in MATLAB environment.

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 Distribution Static Compensator (DSTATCOM) provides active and reactive powers to enable harmonic current elimination, voltage and frequency mitigation, load compensation, and flicker mitigation. In this paper, investigation on power quality improvement in the presence of non linear and unbalanced load is done. The control algorithm provided for DSTAT-COM is p-q algorithm, anti-hebbian algorithm, and Synchronous reference frame algorithm. Comparison among various control algorithm is done on the basis of performance under non-linear and unbalanced load, Total Harmonic Distortion (THD), dynamic performance, complexity and reactive power compensation. The study has been carried out using real time simulator OPAL-RT. OP4510 is used for analysis and validation of results.

SummaryShunt active power filters have been introduced as a way to overcome the power quality problems caused by nonlinear and reactive loads [9, 14, 23]. These power electronics devices are designed with the goal of obtaining a power factor close to 1 and achieving current harmonics and reactive power compensation [5, 6, 15]. The usual approaches [5, 15] for the control of shunt active filters are based on two hierarchical control loops: an inner one that assures the desired current and an outer one in charge of determining its required shape and the appropriate power balance as well. The control structure followed in this Chapter is the one in [7], in which the current controller is composed of a feedforward action that provides very fast transient response, and also of a feedback loop which includes an odd-harmonic repetitive control that yields closed-loop stability and a very good harmonic correction performance. In turn, the outer control law is based on the appropriated computation of the amplitude of the sinusoidal current network and, aiming at a robustness improvement, this is combined with a feedback control law including an analytically tuned PI controller.

The flow of a large current in the neutral conductor of a transmission system is one of the major problems caused by harmonic pollution. This current can assume excessive values and even exceed the current flowing in the phases which can be extremely dangerous both for the equipment and the safety of the personnel. Currently, the parallel or shunt active filter (SAF) or parallel active filter is considered as the most effective solution to mitigate harmonic pollution and restore a sinusoidal current waveform in electrical distribution networks. The SAF can be used to compensate for harmonic currents, as well as that of the reactive power. This paper proposes a SAF circuit based on a four-arm inverter topology. The designed SAF is shown to lead to better harmonic compensation with a reduced THD (Total Harmonic Distortion) level in the presence of nonlinear and unbalanced loads in the network. The other goal of this study is to eliminate the neutral current caused by the unbalance in the polluting loads connected to the distribution network, achieve a near-sinusoidal current waveform and protect the electric network equipment.

Usage of Active power filters is increased in this moderen era as they are capable to reduce harmonics effectively. Shunt Active Filters are proven to diminish harmonics compared to all other devices. Many control strategies has been developed till date to control Shunt Active Power filter. In soft computing techniques generally fuzzy logic has been used with mamdani type of fuzzy logic controller. This paper presents comparison of mamdani and TS type fuzzy logic controller to control the three-phase shunt active power filter. Fuzzy logic method is used to tune PID controller to autotune controller. Instantaneous Reactive Power theory is implemented to generate reference currents. Simulation is done in MATLAB to verify the results.

Problem statement: Now days, power quality has been given attention due to the intensive use of power electronic equipments in all types of industries such as steel, paper, textile industries and so on. These power electronic devices induce harmonic distortion into the supply lines which gives rise to many undesirable effects. Approach: This study presents a new method for harmonic and reactive power compensation with a Fuzzy logic controller and a new control algorithm for active power filter to eliminate harmonics and compensate the reactive power of three phase diode bridge rectifier with RL load. The Fuzzy logic controller was used to predict the reference current values and the firing pulses were generated using hysteresis current controller. The system was modeled and simulated using MATLAB/SIMULINK power system toolbox. Results: The total harmonic distortion for the system is reduced from 29.16-1.08% using the proposed fuzzy logic controller based shunt active filter. Conclusion: The simulation results found were quite satisfactory to eliminate harmonics and improve the power factor for non linear loads.

This paper describes a single-phase modified packed U-cell seven-level multilevel inverter (MPUC7) with finite control set model predictive control (FCS-MPC) for a single phase shunt active power filter application. The shunt active filter can directly inject the harmonic load current and compensate for the reactive power of the load and thus, make the grid current sinusoidal and in-phase with the grid voltage. The active filter improves the power factor and THD of current at point of common coupling (PCC). The MPUC7 is a six switch seven level inverter with only two dc-link capacitors. The mathematical model of shunt connected MPUC7 converter is explained for derivation of the next sample prediction required for FCS-MPC. The cost function for the constraint of tracking current and regulating the two dc-link voltage is mentioned. The filter reference currents are derived using direct control method. The single-phase active filter application is simulated in the Matlab/Simulink to validate the operation and robustness of the FCS-MPC current controller. Various non-linear load changes are simulated to verify the effect on dynamic operation.