This paper analyzes the dynamic characteristics of ±660 kV Yindong HVDC system under fault based on PSCAD. A detailed DC model is established and AC equivalent (Shandong power grid) model of inverter side is designed using a physical equivalent method, then an available method for exchanging AC networks is put forward. The consistency of AC system dynamics is inspected through the 500 kV bus short-circuit test of Shandong grid, the DC system's dynamic characteristics are simulated and analyzed under the DC line fault and commutation failure. Simulation results show that DC line fault location is unrelated to voltage and current trends, and DC system will quickly resume normal operation under the action of control system if line-to-ground flashover failure automatically restore after gone free; electric distance and the fault type are important factors leading to the commutation failure. The AC-DC model can be refined for further research.%基于PSCAD仿真软件研究分析银东±660 kV直流系统故障的动态特性.对直流系统详细建模,采用一种基于物理等效的方法对逆变侧交流系统(山东电网)等值建模,提出一种可行的交流网解环方法.通过山东500 kV母线的短路试验验证了等值前后交流系统动态特性的一致性,对银东直流系统在直流线路故障和换相失败故障情况下的动态特性分别进行仿真分析.仿真结果表明,该直流线路故障位置和故障电压、电流波形的升降趋势无关,线路对地闪络故障如能在去游离后自动恢复,在控制系统作用下可很快恢复正常运行；电气距离和故障类型是导致其换相失败的重要因素.该交直流模型还可进行细化,用于进一步研究.
展开▼
