Three-phase Active Power Filter Current Loop Control Research

Power system nonlinear load is applied more and more widely, which brought a very serious harmonic pollution to the network, at the same time on power system reactive power compensation also raised new requirement, resulting in a series of electricity question. While various sensitive load is applied, which put forward higher requirements to the quality of electric energy. With the harmonic and reactive power compensation problem is increasingly serious, using different means to improve the quality of power supply become very important, which, using active power filter is an important development trend. Its working principle is first detected object size needed to compensate harmonics, and then by the active power filter send and harmonic current of equal size, opposite to the direction of the current compensation, purification of current of power network, so that the grid contains only the fundamental current component. Active power filter on frequency and amplitude variations of harmonic to track, compensation, and the compensation performance is not affected by power impedance.Three-phase active power filter is used to compensate the generated by the nonlinear load harmonics and reactive current. The controller design, directly influences the compensation performance. As a result of the sampling period, zero-order hold and lag effect to take control, digital PI control, the controller in the system under the condition of stability parameters of finite., which limited bandwidth. And the digital PI controller tracking control current is relatively high frequency harmonic current, which also cannot do without static error control.Based on the active power filter current loop pure digital PI control compensation performance finite circumstance, put forward based on the digital PI control and digital repetitive control is a composite control system. In this paper, in order to improve the dynamic characteristic of the system and using the digital PI control, repetitive control is used to improve the tracking performance of the system stability, the derivation and analysis of a composite control of repetitive controller design method, the compensation performance and stability, and the design of system simulation and test. The theory, simulation and experiment prove that the proposed PI based digital control and digital repetitive control in three-phase active power filter can achieve the compound control system dynamic and steady-state characteristics of both the target.