一种具有直流故障穿越能力的混合直流输电系统

A Hybrid HVDC System With DC Fault Ride-through Capability

针对一种整流侧采用电网换相换流器(line commutated converter,LCC)、逆变侧采用LCC与模块化多电平换流器(modular multilevel converter,MMC)串联的混合直流输电拓扑结构进行研究,建立混合直流输电系统模型,推导稳态数学模型,设计系统协调控制策略,并分析其穿越直流故障的机理。在PSCAD/EMTDC仿真环境下搭建混合直流输电的模型,对系统的启动、稳态、交流故障及直流故障穿越特性进行研究。仿真结果表明:系统具有良好的启动和稳态特性;MMC可改善逆变侧交流系统电压稳定性,降低换相失败发生的概率;系统具有直流故障穿越与快速恢复的特性,适用于架空线路输电的场合。

This paper investigated a hybrid high voltage direct current （HVDC） system, in which the rectifier adopts line commutated converter （LCC） and the inverter was composed by LCC in series with the modular multilevel converter （MMC）. The model of this hybrid HVDC system was developed, steady-state mathematical model was deduced, the coordinated control strategy was designed, and the DC fault ride-through capability was analyzed in this paper. The hybrid HVDC system was built in the PSCAD/EMTDC simulation environment. Simulation results show that the hybrid HVDC system possesses favorable start-up and steady performances, the risk of commutation failure is reduced due to the effective regulation of inverter AC busbar voltage by MMC, and the hybrid HVDC system possesses the DC fault ride-through and quick recovery capability, which can be applied for the overhead line transmission.