Network Voltage Distortion To Active Filter Compensation Influence

As technique of power electronics develops, the load with nonlinear, impactive, unbalanced characteristics such as current rectifiers, frequency converters, arc furnaces have been increasingly used in power network in recent years. They generate lots of harmonics and cause distortion in power electrical network current (voltage).Power networks had been polluted by harmonics, which do harm to electrical equipments. Harmonic pollution has been one of the non (?) negligible problems in power supply systems and catches people’s eye. APF(Active Power Filter) is a type power electronic device to restrain the harmonics and compensates the reactive power dynamically..The harmonic current detection is the kernel part of APF’s control system,so the study of the harmonic current detection methods is regarded highly by people therefore. Now, many detection methods is promised that the voltag is the sinusoidal wave,but when the voltage is distorted, few detection methods is studied. In paper, two compensation models based on two compensation objectives are illustrated. One model is pure linear resistance model, the other is current minimum distortion model. The paper inquire into two models’ compensation characteristic,when the voltage is distorted. UPF detection method that is representative of pure resistance and based Fryze power theory is introduced. And pq detection method and ip-iq detection method that are represemtative of current minimum distortion and based on instantaneous power theory. The paper discusses influence of distortion. The paper similate the UPF detection method to test pure resistance model’s compensation characteristic when the voltage is distorted. For pq detection method, voltage distortion influses the detection precision, so in paper, a type improved pq detection method is proposed that is not inflent by voltage distortion..last, by similation of two types pq detection methods , improved pq detection method test effectively.