Shunt Active Power Filter Using Average Power And RLS Algorithm

With the developing of electrical electronic technology, more and more equipments of this kind are used in every field. A big part of these equipments has the characters of nonlinear and time varying. Transient impact, reactive power, high order harmonic wave and unbalance three-phase load make more damage in electrical net. So compensating the reactive power and depressing the harmonic wave to raise the quality of power line becomes very important. Compared with Passive Power Filter (PPF), Active Power Filter (APF) has the higher controllable and faster response. APF can track and compensate every frequency harmonic wave, generate the reactive and harmonic wave power that needed for system automatically. These characters will not effect by system consist and will not magnify harmony wave. Shunt Active Power Filter (SAPF) is getting more application in APF.Recently RLS algorithm in self-adapting algorithm gets more and more application. RLS algorithm is very simple and convergence fast. By using RLS filter, we can filter noise very easy, adjust parameter automatically and promote the characters of RLS filter; finally get the signal we need.Designs a Shunt Active Power Filter and its reference current is a balance three-phase active current which has the same phase with voltage source. There are two parts including in the reference current value. One is the instantaneous active reference current which electrical system should give to the load based on average power. The other that gives by the PI controller is the instantaneous active reference current which electrical system should give to SAPF to maintain the DC-link voltage invariable. The control of second part is familiar to sliding mode control. Calculation of these two parts consist Average Power Algorithm. Controlled by the PWM pulse which get by comparing between the reference compensate current and real generating current, the inverter works to make there is only active current in the electrical system, compensate the reactive power and restrain the harmonic current.DC-line active parameter Adc which can remain DC-link voltage invariable get by using RLS filter overcome hard to get parameters and much ripple in compensation current of PI control. Construction of this kind SAPF is very simple and without phase lock loop device.Test results of simulation get by MATLAB demonstrate the availability and real-time characteristics of this SAPF.