适用于±500kV/3000MW柔性直流输电换流器的电路拓扑损耗特性研究

Research on loss characteristics of topologies for ±500kV/3000MW VSC-HVDC converters

电网异步互联和可再生能源装机容量增加的现实需求,推动柔性直流输电系统已经达到3000MW的级别。当前,受功率半导体器件发展水平所限,需要设计组合式模块化多电平换流器(MMC)拓扑实现柔性直流输电系统的扩容。但是,不同组合方式下系统参数设计以及所适用IGBT器件类型差异很大,这对多变量下的组合式换流器损耗特性研究提出了挑战。本文首先提出了一种单台MMC的损耗计算方法,然后推导了组合式MMC的损耗计算解析表达式。在此基础上,对比分析了采用4500V/1500A和4500V/3000A IGBT器件的情况下,四种适用于±500kV/3000MW柔性直流输电换流器的组合式MMC拓扑损耗特性。PSCAD/EMTDC仿真结果表明,四种拓扑中并联式MMC拓扑的损耗最小,验证了损耗特性分析的正确性。

With the increasing demand of asynchronous power grid interconnection and renewable energy explora- tion, the capacity of the voltage source converter based high-voltage direct current （VSC-HVDC） transmission sys- tems has reached the rating of 3000MW. Because of the limitations of the current power semiconductor technology, it is necessary for the combined modular multilevel converter （MMC） topologies to realize the large capacity VSC- HVDC system. However, the differences of the system parameters and IGBT modules impose great challenge on the analysis of the loss characteristics for different combined MMC topologies. The loss calculation method for the single MMC was proposed in this paper firstly; then the analytical expression of the combined MMC loss was derived. Ac- cording to that, the loss characteristics of four combined MMC topologies for the ±500kV/3000MW VSC-HVDC system were analyzed based on the 4500V/1500A and 4500V/3000A IGBT modules. PSCAD/ EMTDC simulation results verify the correctness of the loss characteristics and show that the loss of the combined MMC in parallel is the smallest.