基于高频隔离的负序级联式补偿电路拓扑

提出了一种可以级联应用于高压场合的负序电流补偿电路拓扑。此电路通过内部相互耦合的高频隔离变压器进行负序能量交换,实现了对于三相四线制或者三相三线制中不平衡电流的补偿。这种拓扑克服了传统按照星型连接的电压型H桥级联构成的APF应用于高压系统中无法进行负序电流补偿的缺点,实现了相间能量交换,并且能够在单级和多级级联后均可进行无功,谐波和负序电流的补偿。系统通过三绕组变压器降低了直流侧电容电压的二次脉动,减小了所需电容量。文章通过对两级级联系统的仿真,证实了电路拓扑的可行性,所构建的小功率实验平台进一步验证了所提出方案的有效性。

Cascade Negative Sequence Compensating Circuit Based on High Frequency Isolation

A new topology of compensating three-phase negative-sequence current is given which can be cascaded for high voltage level.This contains three windings high frequency transformer which is the core of the system to realize negative sequence energy exchange in three-phase four-wire or three-phase three-wire system.Comparing to conventional APF based on wye-connected cascade multilevel inverter in high power field which consists of cascaded H-bridges,the new circuit conquers the difficulty of compensating negative sequence current and makes the energy exchange between phase and phase.It can also work as APF to compensate the reactive and harmonic currents.The system reduces DC-link voltage pulsation by using three windings high frequency transformer so as to reduce dc-link capacitance.The simulation results about two-level systems are given to verify the topology and at last the experiment results are also presented in a low power platform.