基于零电压直流均压电路和分层控制的中压级联有源滤波器

级联有源滤波器拓扑结构简洁,可不经变压器直接接入中压配网,但级联单元的数目大,控制繁杂,并且直流侧电容电压存在不均衡问题。该文提出一种中压级联有源滤波器分层控制策略,分离系统上层主功能控制和下层单元控制,扩大主控制计算的时间裕度,实现较复杂的控制算法,并保证系统动态响应速度;同时提出一种硬件辅助箝位电路及其软开关控制策略,实现直流侧电容能量交换与均压控制,并且通过相位与模式控制使辅助回路开关零电压(zerovoltage switching,ZVS)运行,提高辅助回路效率,降低开关噪声。仿真和实验研究证明:分层控制策略与软开关辅助箝位措施是实现中压级联有源滤波器的有效方法。

Cascade active power filter based on ZVS DC-link clamping circuit and hierarchical control for medium voltage applications

A cascade active power filter(CS-APF) with additional stages can be directly connected to medium-voltage networks without a transformer.However,the system has a large number of stages and is quite complicated.The system also has a direct current(DC)-link capacitor voltage unbalance.The hierarchical control strategy for CS-APF described in this paper separates the top main function control and the bottom unit control and enlarges the computational time margin for the main control algorithm.The complicated algorithm can still be implemented with quick response.An auxiliary circuit using soft-switch control for DC-link capacitor voltage clamping transfers energy between the capacitors to balance their voltages and ensure system reliability.The auxiliary circuit operates as a zero-voltage switch using phase and mode control.The circuit switching frequency and efficiency are improved and the electromagnetic interference(EMI) noise is suppressed.Both simulations and experiments show that the hierarchical control and the clamping circuit enable stable operation of the medium-voltage CS-APF.