并联型APF补偿容性非线性负载不稳定机理研究

摘要

Instability can occur when a parallel active power filter whose reference current is deduced based on load current detection is applied to compensate capacitive nonlinearity load. The root cause of instability is the mismatch and the mutual influence of input and output impedance in cascade system. The mathematical model of parallel active power filter which is applied to compensate capacitive nonlinearity load is primarily built for the problem in this paper, and the impedance characteristic of input and output part in cascade system is analyzed based on the Middlebrook impedance analysis theory, the root instability cause is discussed by the stability criterion in cascade system, finally, the simulation and experimental results validate the correctness of the theoretical analysis.%基于负载电流检测方式的并联型有源电力滤波器补偿容性非线性负载时会发生不稳定的现象，其根本原因在于整个级联系统输入输出级阻抗不匹配，存在相互影响。针对这一问题首先建立并联有源滤波器补偿容性非线性负载时的数学模型，其次基于 Middlebrook 阻抗分析法推导出整个级联系统输入输出级的阻抗特性，并根据级联系统稳定性判据标准分析了不稳定产生的根本原因。仿真和实验结果验证了理论分析的正确性。