一种直流电压的串联有源补偿电路及其在多端直流电网中的应用

Series-Connected DC Voltage Harmonics Compensation Circuit and Application in Multi-Terminal DC

直流整流电路中直流侧通常通过并联电容方式进行滤波,但直流侧电容可能造成短路时巨大的放电电流,同时在高压应用中,直流侧电容体积大、成本高。为此,该文提出一种串联的有源补偿电路,输出谐波电压以补偿整流器输出电压中的谐波,从而不用电容即可实现直流稳压输出。为了稳定该电路的独立电容电压,以及准确地对谐波电压进行补偿,该文提出基于双环PI和基于滑模变结构的两种电压控制方法,并对负载突变情况进行了分析。针对该电路应用于多端直流电网(MTDC)带来的问题,该文提出一种对潮流进行控制的主从结构方法,以避免不同控制功能的相互影响。最后,通过大量仿真对所提出的电路及控制方法进行了验证。

The rectifiers always employ bulky capacitors to filter the harmonics,but the capacitors in DC grid will discharge gigantic current during DC short conditions,furthermore,the capacitors occupy space and cost much in medium voltage application.This paper proposed one series-connected active voltage compensation circuit,which generates the negative harmonic voltage and attenuates the rectifier output voltage fluctuations without DC grid capacitors.This paper proposes double-loop PI and sliding mode control methods to track the harmonics voltage with excellent performance and maintain the independent capacitor voltage of the compensation circuit constant.The abruptly load changing condition is also analyzed.Furthermore,this series-connected circuit is applied in multi-terminal DC(MTDC)and one master-slave control structure is employed for power flow control avoiding interferences between multi-purpose functions.The proposed circuit and control methods are verified through comprehensive simulations.