有源滤波器参考信号的一种新的校正方法

为改善控制延时对有源滤波器(APF)补偿效果的影响,本文从分析数字化有源滤波器产生延时的原因出发,建立了APF控制系统的传递函数模型。用MATLAB对该传递函数进行频域特性分析可以发现,延时不但造成了输出参考电流相位的滞后,而且还对其幅值产生了影响;同时,由于延时的存在,系统电压的量测精度对参考电流的影响也是不可忽略的。在以上分析结果的基础上,本文提出了一种从参考电流的幅值和相位入手,对控制系统延时进行补偿的策略,并且兼顾系统电压量测精度对参考电流的影响。现场实验充分验证了该补偿策略的正确性和易用性。

A new compensation method for current reference of active power filters

As a dynamic harmonic filtering equipment,the active power filter(APF) is asked to have a very fast response to the compensated signal.However,the process of data collection,arithmetic calculation and PWM bring time delay more or less.Obviously,the time delay has a negative impact to the overall performance of an APF.To alleviate the influence of time delay in APF,this paper sets up a transfer function for the APF control system,in which time delays introduced by different processes are considered.The frequency response of the transfer function is analyzed in MATLAB.The fact that both the magnitude and phase of the current reference are distorted is revealed.Besides,it is observed that the system voltage at the link point has significant influence to the current reference.Based on the analysis,a new method to compensate the time delay of APF control system is proposed,which modifies both the phase and magnitude of the current reference while it also takes into account the influence of system voltage.Experiment results validate the necessity of the modification and demonstrate the effectiveness and efficiency of the proposed method.