四桥臂有源滤波器在静止坐标系下的改进PR控制

有源电力滤波器(active power filter,APF)电流环控制要求补偿电流无误差地跟踪给定信号,传统的dq坐标系下P I控制很难消除稳态误差。采用并联的比例谐振(proportional resonant,PR)控制器,对不同频率的正弦分量进行跟踪控制,实现零稳态误差跟踪。针对电网频率波动和三相不平衡问题,在坐标系下采用改进PR控制器实现电流跟踪控制。在详细分析PR控制器各参数对性能指标影响的基础上,总结参数的调试方法,并给出控制器离散化方法。通过仿真与实验对所提控制策略进行验证,APF投入后,电网电流畸变率下降,中线电流有效值减小,负载和频率波动时仍有较好的补偿效果。该结果表明,所提的改进PR控制策略可以有效地抑制谐波,较好地解决三相不平衡问题,对负载突变和频率波动均有良好的适应性。

An Improved Proportional Resonant Control Strategy in the Static Coordinate for Four-leg Active Power Filters

The current loop control of active power filters(APF) requires the compensation current to track the given signal without any error,while it is difficult to eliminate steady-state errors by using the traditional PI controller in the synchronous dq frame.In this paper,the proportion resonant(PR) controller was adopted to track the different frequency component,thus to obtain zero steady-state errors.As to the grid frequency fluctuation and the unbalanced problem of three-phase systems,the improved controller in the coordinate was proposed.On the basis of analyzing the effects of PR controller parameters on the performance index,the paper summarized the debugging methods of the parameters.And the Pre-Warped Tustin Transformation was used to discretize the controllers.The proposed strategy was verified through simulation and experiment results.The total harmonic distortion(THD) values of grid currents after filtering reduced and the root mean square value of the neutral current dropped.In addition,the compensating effects was still satisfying while load and frequency were fluctuating.The results suggest that the proposed improved PR control strategy can effectively restrain harmonics and solve the unbalanced problem of three-phase systems.Moreover,this method has excellent adaptability for the load and frequency fluctuation.