Research On The Active Power Filter Control Strategy Based On Sliding Mode Control

With the nonlinear load increasing of rectifiers and frequency converters in the power system, the concussion and imbalance caused by nonlinear loads results in voltage wave and current wave distortion. Sometimes it will have bad influence on the power quality. APF(Active Power Filter) is widely used in harmonic pollution restraint. It is important to detect the current signals and control compensation signals in APF. So the control of compensation signals is focused on in the paper. Though hysteresis loop, deadbeat and triangular carrier control method are popular nowadays, yet they don?t show effective control considering fast response, strong robustness and switching frequency of electronic devices at the same time. Sliding mode variable-structure control method will perform better in solving such problems.Sliding mode variable-structure control is able to guarantee system asymptotic stability with less influence of system parameter and external interference. But it also has some problems such as fluctuation. On one hand the design adopts modified sliding mode control method to improve response speed of control system. on the other hand in order to slack down fluctuation, the concept of boundary-layer ?quasi-slide control? is introduced, in which outside boundary layer improved sliding control is chosen while inside hysteresis loop control. Based on the analysis of the D-Q model of three-phase sources model and PWM converters, the paper takes improved sliding control method as current tracking control strategy and it shows better fast response and robustness. Compared with PWM control strategy, the simulation of improved sliding mode control method performed in MATLAB shows that the shunt APF has better static and dynamic property.