并联型有源滤波器H_∞控制设计

Design of H_∞ control for shunt active power filter

在并联型有源滤波器的控制过程中,前馈控制能够快速跟踪负荷波动,但需要精确的模型和参数。为了消除前馈控制指令与理想控制指令之间误差对补偿效果的不利影响,首先建立了并联型有源滤波器的数学模型。在此基础上,将误差看作是对控制系统的外部干扰,然后基于H∞控制理论,设计了并联型有源滤波器的鲁棒控制器。对于给定的干扰抑制比,通过求解Riccati方程即可得到相应的反馈参数;在Riccati方程有正定解的前提下,干扰抑制比越小,闭环系统的干扰抑制能力越强。该控制器补偿效果良好,同时还可保证闭环系统的稳定性。仿真分析表明,在所提控制器的作用下,无论是在稳定负荷还是在负荷突变的条件下,有源滤波器都有较好的补偿效果。

For the control of shunt APF（Active Power Filter）,feedforward is an effective way to track the load variation,but accurate models and parameters are demanded. To eliminate the influence of errors between realistic and ideal control instructions on the compensation effectiveness of APF,a state-space model of distribution system with APF containing a HPF（High-Pass Filter） is established. Taking errors as unknown disturbances to the system,a supplementary feedback controller based on the H∞ control theory is designed. With a given interference suppression ratio, corresponding feedback parameters can be obtained by solving the Riccati equation. When positive definite solution exists,the smaller the interference suppression ratio is,the stronger interference suppression capability the close-loop system will have. The controller ensures the stability of the close-loop system with effective compensation. Simulation results prove that,the APF with the designed controller performs well for both stable load and sudden-changing load.