The conventional control strategy for active power filters (APFs) is essentially a nested structure, where the output of the outer voltage loop will affect the command current of the inner loop, inevitably impairing the performance in harmonic compensation. In this article, to enhance the harmonic-compensation performance, the output of the dc-link voltage loop has been modified and added as a disturbance to the current loop, which forms a paralleled structure. Thus, the pure command current can be achieved and not affected by the output of the voltage loop. Parameters of the proposed paralleled strategy are designed considering both stability and dynamic responses, and larger phase and gain margins are achieved. In addition, a compound PI controller has been designed to avoid the integral overflow problem. Finally, experimental results verify that, though with a relatively slow the dc-link voltage response, the proposed paralleled strategy can achieve a faster and more precious current control, and a better performance in harmonic compensation compared with the conventional nested strategy.

中文翻译：

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三相有源电力滤波器复合PI控制器的并行电流和电压控制策略

传统的有源电力滤波器（APF）控制策略本质上是一种嵌套结构，外环电压的输出会影响内环的指令电流，不可避免地影响谐波补偿的性能。在本文中，为了增强谐波补偿性能，直流母线电压环路的输出已被修改并添加为电流环路的干扰，形成并联结构。因此，可以实现纯命令电流并且不受电压环路输出的影响。所提出的并联策略的参数设计考虑了稳定性和动态响应，并且实现了更大的相位和增益裕度。此外，还设计了复合PI控制器来避免积分溢出问题。最后，实验结果证明，尽管直流母线电压响应相对较慢，但与传统的嵌套策略相比，所提出的并联策略可以实现更快、更精确的电流控制，以及更好的谐波补偿性能。