Active Power Filter

In this report the three phase three wire shunt active filter based on the instantaneous real and reactive power control strategy with PI controller have been analysed. It is found from the simulation results that shunt active power filter improves power quality of system by eliminating harmonics of non-linear load. The dc bus voltage has been maintained constant equal to the reference voltage by all PI and Fuzzy controllers. It has been found that these robust and nonlinear control proves to be better than conventional control. The THD of the source current is below 5% according to simulation result and it is in permissible limit of IEEE standard.

II. FOUR-LEG CONVERTER MODEL It consists of various types of power generation units and different types of loads. Renewable sources, such as wind and sunlight, are typically used to generate electricity for residential users and small industries. Both types of power generation use ac/ac and dc/ac static PWM converters for voltage conversion and battery banks for long term energy storage. These converters perform maximum power point tracking to extract the maximum energy possible from wind and sun. The electrical energy consumption behavior is random and unpredictable, and therefore, it may be single- or three-phase, balanced or unbalanced, and linear or nonlinear. An active power filter is connected in parallel at the point of common coupling to compensate current harmonics, current unbalance, and reactive power. It is composed by an electrolytic capacitor, a four-leg PWM converter, and a first-order output ripple filter, as shown in Fig. 1. This circuit considers the power system equivalent impedance Zs, the converter output ripple filter impedance Zf, and the load impedance ZL.

This paper focuses on modeling and analysis of Custom Series Active Power Device (SAPF). MATLAB/Simulink primarily based models for Series Active Power filter (SAPF) is bestowed. Among numerous PWM techniques, physical phenomenon band voltage management PWM is popularly used attributable to its simplicity of implementation. This legendary technique doesn't want any data concerning system parameters. The SAPF is simulated for various voltage variations at input generated by the 3 section programmable supply and also the results square measure bestowed. Key Words: Series Active Power Fault (SAPF), Power quality improvement

The control strategies for active power filter is mainly divided into three parts i.e. (i) Detection of load current, (ii) Detection of source current, & (iii) Detection of source voltage. Two types of connection can be achieved through active power filter namely, series connected active power filter and parallel connected active power filter or shunt active power filter. Series APF is used to mitigate the harmonics present in the source voltage whereas, parallel or shunt APF is used to mitigate the source current harmonics. Shunt active power filter requires a steady maintenance of DC voltage across the input terminal of the inverter. This again requires charging of a capacitor in equal interval period of times. The present model is based on PI controller based SAPF which is used to mitigate the current harmonics in the system.

ABSTRACT: Recent wide spread applications of power electronic equipments have caused an increase of the harmonic disturbances in the power systems. The nonlinear loads draw harmonic and reactive power components from AC mains. Here a PI controlled shunt active power filter and fuzzy controlled shunt active power filter are presented to eliminate harmonics and to compensate the reactive power of single phase rectifier. The performances of both controllers are analyzed from the simulation results obtained.

Device (SAPF). MATLAB/Simulink based mostly models for Series Active Power filter (SAPF) is given. Among varied PWM techniques, physical phenomenon band voltage management PWM is popularly used as a result of its simplicity of implementation. This renowned technique doesn't would like any info regarding system parameters. The SAPF is simulated for various voltage variations at input generated by the 3 part programmable supply and therefore the results area unit given.

Abstract— In this paper, a three-phase four-wire system connected a nonlinear load, dc/ac four leg voltage source converter to act as a four leg Active Power Filter (APF) using of instantaneous power theory is presented. The use of a four-leg voltage- source inverter allows the compensation of current harmonic components, as well as unbalanced current generated by single- phase nonlinear loads. The instantaneous power theory is applied to design the APF controller, which shows reliable performances. The MATLAB/SimpowerSystems tool has proved that the proposed control technique compensate the harmonic current drawn by nonlinear loads and controls the reactive power flow.

Performance of shunt active power filter is checked with the use of MATLAB software. In the proposed scheme one type of load has been considered as nonlinear loads. Fig. 9 shows the performance of shunt active power filter under restive rectifier load. In this case the before the insertion of the shunt active power filter, Total Harmonic Distortion (THD) of source current was 30.26 % and after the insertion it comes down up to 4.42 %. Output result of load current for this case is shown in fig. 7.The shunt active filter was inserted at 0.06 second in the system.

Other than that, a three phase shunt active filter can mitigate harmonic disturbances in power system. Consequently, the project’s objective is to use the three phase shunt active power filter as another solution in mitigation of harmonic distortions. The harmonic distortion also can disturb the performance in power quality for power system. The control system of P-Q theory will be used to develop shunt active power filter. The output waveform will be carried out in a simulation. The simulations will simulate the different waveform for linear and non-linear load. As to analyse the harmonic distortion, appropriate graph of total harmonic distortion also implemented as the result of the project.

Abstract- This paper tells the contamination issues created in power systems due to the non-linear features and fast changing of power electronic equipment. Power quality issues are turning stronger because sensitive equipment will be sorer for market competition reasons, equipment will continue contaminating the system more and more due to cost increase caused by the built-in competition and sometimes for lack of enforced regulations. Active power filter have been developed over the year to solve these problems to improve power quality. Among which Shunt active power filter (SAPF) is used to control the load current harmonics and reactive power compensation. In this work both PI controllers based Fuzzy Logic checked three-phase SAPF to pay tones and reactive power by non-linear load to improve power quality is enforced for three-phased three wire systems. Fuzzy controller is based on linguistic description and does not require a mathematical model of the system. A MATLAB program has been formulated to stimulate the system operation. Various simulation results are demonstrated under steady state considerations and performance of fuzzy and PI controllers is equated. PWM pattern generation is based on carrier less hysteresis based current control to obtain the switching indicates to the voltage sourced PWM converter.

Improved dynamic current harmonics and a reactive power compensation scheme for power distribution systems with generation from renewable sources has been proposed to improve the current quality of the distribution system. Advantages of the proposed scheme are related to its simplicity, modeling, and implementation. The use of a predictive control algorithm for the converter current loop proved to be an effective solution for active power filter applications, improving current tracking capability, and transient response. Simulated and experimental results have proved that the proposed predictive control algorithm is a good alternative to classical linear control methods. The predictive current control algorithm is a stable and robust solution. Simulated and experimental results have shown the compensation effectiveness of the proposed active power filter.

power filters are connected to AC mains in order to eliminate voltage variations and harmonic components. Shunt active power filter eliminates the current harmonic components working as a source with only the harmonic components and power factor correction, so that only the fundamental component is supplied in the AC mains.

Abstract: This paper presents the performance analysis of shunt active power filter using UVT(Unit V ector Template) method. This shows how to reduce or eliminate the various power quality issues for a three-phase balanced and unbalanced composite load i.e. (linear load and non-linear load) by using shunt active power filter. The governing method used to reduce the various power quality issues is UVT method for both three-phase balanced and unbalanced composite load. The various power quality issues are – harmonic compensation, reactive power compensation and improvement of power factor. Simulation results are tabulated for both three-phase balanced and unbalanced composite load.

Hybrid active filter topologies comprise of passive and active filters. The passive filter has an essential part to tune at key recurrence and diminish the power rating of APF. In literature, many sorts of passive filters are applied. Most basic filters is LC filters. The LC filter comprises of an inductor and capacitor in arrangement tune a solitary recurrence. The LC circuit gives a zero impedance way for a particular harmonics current to be sifted. LCL yield filters demonstrate more compelling execution than LC yield filters. A few reviews lean toward this sort of channel. RLC filters comprise of a resistor, an inductor and a capacitor associated in arrangement. It constitutes a consonant isolator. The resistor is utilized for damping .Injection sort of filter is made by including a LC circuit that is tuned to key recurrence of the transformer. In expansion, this topology can be connected for high voltage levels in light of the fact that the current at the basic recurrence does not stream over the active filter. Another sort filter topology is parallel full filter. Another passive filter topology that is tuned at the basic recurrence of the framework is utilized rather than customary passive filter topology. This filter comprises of parallel LC with arrangement. LC is tuned at basic recurrence of the framework. C in parallel LC filter and series L is tuned at wanted harmonics recurrence. This filter exhibits high impedance at basic recurrence segment so it forestalls to stream basic recurrence segment over the active power filter. For the consonant recurrence, this filter shows low impedance so the present harmonics stream over active power filter. The power limit and loss of the inverter are diminished.

In past passive filters have been used for elimination of harmonics which are simple and low cost. However, the use of passive filters has many disadvantages, such as large size, tuning and risk of resonance problems. The rapid improvement in power semiconductor device technology, active power filters (APF) have been considered as an effective solution for this issue. One of the most popular active filters is Shunt Active power filter (SAPF) for mitigating current harmonics .Since the concept, " Active power filter " ,was first developed by L. Gyugyi [l] in 1970s. The control strategy for active power filter was concluded by H. Akagi [2] as three modes, load current detection, supply current detection and voltage detection, for different applications. In general the series active power filter is preferable to compensate the harmonics in supply voltage, while parallel active power filter is more suitable to compensate the harmonics in the supply current. The Active power filters (APF‟s) firstly developed by Akagi, provide better performances of harmonic elimination [2-5]. The (SAPF) control strategy involves not only the production of currents whether to eliminate the undesired harmonics, but also to recharge the capacitor value requested by Vdc voltage in order to ensure suitable transit of powers to supply the inverter. The storage capacitor „C‟ absorbs the power fluctuations by the compensation of the reactive power, harmonics and the losses of the converter for proper active power control. The average voltage across the capacitor terminals must be kept at a constant value. Generally, PI controller is used to regulate this voltage. With variation of load perturbations and non linear conditions, detecting of PI parameters is difficult and time taking process other disadvantage is inability to improve the transient response of the system. The past decade interest on Artificial Neural Networks (ANNs) is increased because of its learning ability, high speed recognition and able to adapt themselves to any system. Warren Mc Culloch and Watter Pitts [9] in1943 created a computational model for neural networks based on mathematics and algorithms, and back propagation algorithm was created by Paul Werbos [13] in 1975. Particle swarm optimization (PSO) algorithm is an optimization technique inspired by the movement of particles (birds, fishes) which is introduced by Kennedy J, Eberhart R [15] in 1995.

In this paper the performance analysis of shunt active power filter using instantaneous reactive power theory have been carried out. Simulation results show the effectiveness of shunt active power filter for harmonic elimination in distorted source current. Two types of loads have been considered to check the validity and flexibility of the proposed scheme. In both the cases THD of source current reduces from 27.17 % to 1.02 % and 25.82 % to 2.46 %, which comply with IEEE-519 standard of harmonic control.

This paper discusses the capabilities of a MFGCI for enhancing the power quality in a grid connected distributed generation system. It has been shown that the DG inverter can be effectively utilized to inject real power from the RES in the forward and reverse power flow modes and/or operate as a shunt active power filter. The proposed closed loop active power control strategy achieves accurate power tracking with zero steady state errors under ideal and non- ideal supply conditions and can be used as a control technique for integration of DG inverters to the utility grid. The method laminates the need of extra power conditioning devices to improve the power quality. The effectiveness of the control scheme is verified under balanced and unbalanced non linear load conditions. With the proposed method the combination of nonlinear loads and the DG inverter is seen as a resistive load at the PCC and the grid currents re maintained sinusoidal. To proposed with fuzzy logic controller and maintain the grid currents re maintained sinusoidal

ABSTRACT:Power quality is a big concern nowadays.It become important, especially with the introduction of advanced power electronics devices and expanded network. Power quality problem is the issue that takes place before a non-standard voltage, current, or frequency, leading to end-use hardware failure. One of the main issues addressed here is voltage sag. To resolve this issue, one must use custom and advaned power devices. One of these devices is the Shunt Active Power Filter (SAPF), a modern power device used in the most efficient power distribution networks. To deal with such power quality problems at transmission and distribution level , devices like SAPF plays important role. .

Fig.6 shows the basic compensation principle of a shunt active power filter. It is controlled to draw/supply a compensating current I from / to the utility, so that it cancels current harmonics on the AC side, and makes the source current in phase with the source voltage. The load current waveform, the desired mains current and compensating current injected by the active filter are containing all the harmonic components to make mains current sinusoidal.

Abstract: Active filters are widely employed in distribution system to reduce the harmonics produced by non-linear loads. These results in voltage distortion and leads to various power quality problems. Shunt Active Power Filters are the best solution for the elimination of harmonics occurred in the power system. This paper presents the optimization of shunt active power filter parameters based on fuzzy logic control, which is employed to drive the switching signals and also to choose the optimal value of the coupling inductance. The fuzzy control is based on a linguistic description and does not require a mathematical model of the system. It can adapt its gain according to the changes in load. The indirect current control method is used for calculating the compensating currents. A fuzzy logic based controller is developed to control the voltage of the DC side Capacitor. The conventional hysteresis controller gives very fast response and good accuracy, but it causes uneven switching. This work presents and compares the performance of the fuzzy-controller with a conventional controller under constant load. The harmonic distortions are analysed and compared. The total Harmonic Distortion, Individual harmonic content with respect to % of fundamental in Supply current, have been analysed. The proposed systems are implemented with Mat lab/Simulink.