Research On Three-Phase Shunt Active Power Filter Control Method

With development of power electronic technology,various power electronic devices account for an increasing proportion of production and life,resulting in a large number of harmonics.Active Power Filter is effective power electronic equipment used to compensate harmonics and reactive power in real time.Because of APF good compensation effect,it has always been the key research direction of experts and scholars at home and abroad.By taking Three-Phase shunt Active Power Filter(APF)as research object,harmonic current detection method,and harmonic currents control method,and the DC-link voltage control method in its control system were studied.DC-link voltage control method was mainly researched.Shunt APF mathematical model was established,and APF working principle was analyzed at the same time.Against the problem of detection delay caused by use of low-pass filters in design process of i_p-i_q detection method,designed an integral average filtering link to replace the filters.The i_p-i_q detection method adopting the integral average filtering link,effectively improves real-time detection performance under the premise of ensuring detection accuracy.After analyzing common current control methods,the current PI decoupling control method was adopted.And SVPWM was used for modulation.The current control method has strong ability to compensate low frequency harmonics,and high compensation speed and compensation accuracy.By analyzing and studying design process of the active disturbance rejection control method and the control principle of Sliding-mode control,a Sliding-mode active disturbance rejection control method stably controlling the DC-link voltage was proposed.Two parts of the control method are a linearized tracking differentiator and a linearized extended state observer.At the same time,Sliding-mode control design method was used in design process of its control rate part,and the chattering was decreased.DC-link voltage response speed of this method is improved,and DC-link voltage anti-disturbance ability is enhanced,and number of parameters that need to be adjusted is effectively reduced,and stable DC-link voltage is implemented.MATLAB software was used for simulation,and an APF prototype was developed for experimental verification.Simulation results and experimental results indicate that the detection method using integral average filter link can smoothly extract the harmonic current with a short delay.Compared with other current control methods,current PI decoupling control method and modulation method can track harmonic currents in real time and have high compensation accuracy.The shunt APF DC-link voltage sliding-mode active disturbance rejection control method has high dynamic response speed,small overshoot,strong anti-interference ability,and low grid-link current distortion rate after compensation.