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良好的控制策略是实现并联型有源电力滤波器(active power filter,APF)补偿功能的关键。由于并联型APF常规电流PI控制方法的闭环增益受系统稳定性条件约束,并联型APF对负载主要谐波分量补偿不充分。针对该问题,提出一种用于APF的新型选择性谐波电流控制策略。该控制策略在常规电流PI控制策略的基础上,对负载电流主要谐波(该文主要指5次、7次谐波)单独提取与控制,而对其余次谐波采用一个常规电流PI控制器控制。该设计方法,增大了系统对主要谐波分量的跟踪增益,提高了APF对谐波的补偿率,实现了控制系统更好的频率响应。将该方法应用于实验室制作的一台30 kVA并联型APF实验装置,可将电流总谐波畸变率(total harmonic distortion,THD)由23.21%补偿为3.75%。仿真与实验结果证明了以上结论。
A good control strategy is the key to implementing the parallel APF compensation function. Since the closed-loop gain of the parallel current-mode PI control method is constrained by the system stability conditions, the shunt APF does not compensate the main harmonic components of the load. Aiming at this problem, a new selective harmonic current control strategy for APF is proposed. The control strategy based on the conventional current PI control strategy, the main load current harmonic (mainly referred to 5, 7 harmonics) separately extracted and controlled, while the rest of the harmonic using a conventional current PI controller control. The design method increases the tracking gain of the system for the main harmonic components, improves the compensation rate of APF to the harmonics, and achieves a better frequency response of the control system. Applying this method to a laboratory-produced 30 kVA parallel APF experimental device, the total harmonic distortion (THD) of current can be compensated from 23.21% to 3.75%. Simulation and experimental results prove the above conclusion.