The Research On Hybrid Active Power Filter System

As an important device of Flexible AC Transmission System (FACTS), Active Power Filter (APF) can not only compensate all kinds of different exponential harmonics, but also chock back fulgurous variety and compensate reactive power. Its compensation performances doesn't influenced by the system impedances. The configuration, operating principle and application research development of APF are all introduced.By means of vector analysis, the detection flow for harmonic and reactive current is deduced based on revolving synchronously around dqO in synchronous reference frame. When appearing distortion voltage or in asynchronous three-phase circuit, the detection phase excursion and influences are analyzed. Furthermore, in order to control it, the method of locking phase with digit is put forward. The method can reduce largely detection influences from phase excursion of voltage signal, it can also simplify circuit configuration and improve greatly response time and precision.The control method of PWM inverter and the main device of APF are studied in the paper. To track and control hysteretic current of PWM inverter, the control method based on optimal voltage vector is adopted. Comparing with the conventional ones, this method has its distinct advantages as follows: Firstly, when the system reference voltage vector changes rapidly and when it is hard to forecast, the new method can track rapidly and judge accurately where it is; Secondly, it can reduce effectively current compensation error and decrease switching frequency of voltage source. Finally, it can improve capability of active power filter.