基于电池储能的MMC-HVDC系统的建模与仿真

由于交直流混联电网中的交流系统和直流系统之间存在有功功率耦合,因此基于模块化多电平换流器(MMC)的高压直流输电(HVDC)系统无法完全隔离故障时交直流侧之间的相互影响。文中提出将基于电池储能系统(BESS)的MMC应用于HVDC系统以实现交直流侧功率解耦控制的方法。首先分析了基于BESS的MMCHVDC系统的基本结构和工作原理。然后,基于数值积分和嵌套的快速仿真方法,推导了基于BESS的子模块和基于BESS的MMC换流器的戴维南等效电路。最后,搭建了±400 k V的两端MMC-HVDC系统对所提建模方法和系统的解耦效果进行了验证。结果表明,基于BESS的MMC-HVDC系统交流侧有功功率和直流侧功率可以彼此解耦,在交流或直流故障期间可以保持功率的正常输送。

Modeling and simulation of battery energy storage system based on MMC-HVDC

There is active power coupling between ac system and dc system in ac/dc interconnected power grid, and modular multilevel converter based HVDC (MMC-HVDC) system could not completely isolate the fault from ac system to dc system or dc system to ac system. In order to achieve the effect of independent decoupling operation of HVDC system and make full use of "firewall" function of the MMC-HVDC system, the battery energy storage system (BESS) based MMC-HVDC system is a preferred choice. For the BESS based MMC-HVDC system, this paper firstly analyzes the basic structure and operation principal. Then, based on numerical integration and nested fast and simultaneous simula-tion approach, this paper derives the Thévenin equivalent circuit of BESS based SMs and BESS based MMC. The case studies are performed on a ±500 kV 2-ternimal MMC-HVDC system. The time-domain simulation results show that the ac side active power and the dc side power of the BESS based MMC-HVDC system can be decoupled from each other, and the transmitting power during and after the ac or dc fault can be kept.