VSC-HVDC大功率拓扑结构研究

针对VSC-HVDC系统在高压大功率应用场合下存在损耗大、直接串联电力电子器件数量巨大并引起可靠性差的问题,在分析现有VSC-HVDC拓扑与大功率化方法的基础上,从降低电力电子器件直接串联数目、器件开关频率和简化主电路拓扑结构3个方面出发,提出了一种大功率多模块式VSC-HVDC拓扑。换流器模块工作在相对较低的开关频率下,因此可以选用高压大电流、低导通损耗而开关频率却相对较低的开关器件如IGCT等。设计了基于该系统模型的控制系统并确定了其控制策略。仿真结果证实了提出的VSC-HVDC拓扑及其控制策略的有效性。

Research on the High Power Topology of VSC-HVDC System

Traditional VSC-HVDC topology has some problems such as high power loss and huge amount of power electronic devices in series to meet the demands of high voltage stress,and all these lead to low reliability,so it is most important to introduce more applicable topology for high voltage and large power VSC-HVDC systems based on the vested power electronic devices and control technologies so as to decrease the device number in series and its operating switching frequency,and to simplify its topology.Therefore,a novel high-power multi-module based VSC-HVDC system is proposed based on the analysis of the vest topologies and power electronic devices.Each VSC module operates with a fairly low switching frequency(300 Hz)which is much lower than the traditional two-level VSC-HVDC system's(about 2 kHz),and thus the low-switching power electronic device such as IGCT could be selected due to its high power and low conducting loss.The novel topology and its control strategy are evaluated by the simulated results.