天广直流逆变侧直流电压测量偏低故障时直流系统响应特性仿真研究

Simulation Study on the Response Characteristic of Tian-Guang DC Transmission System of Low DC Voltage Measurements at the Inverter Side

近期天广直流多次发生因逆变侧直流电压测量偏低故障导致直流系统电压异常升高的事件。为了研究这一事件的产生机理,结合控制策略对天广直流系统电压异常升高的原因进行了详细分析,并通过大量RTDS仿真试验,研究了在不同故障程度、功率水平、运行方式下发生逆变侧直流电压测量偏低故障时直流系统的过压水平和控制保护响应特性。仿真结果表明,逆变侧直流电压测量偏低会造成直流系统过压,且直流系统在不同的故障程度、功率水平和运行方式下有不同的控制保护特性,特别是在大功率模式和降压运行方式下可降低直流过压水平。

Several abnormal voltage elevation events of Tian-Guang DC transmission system happened recently resulting from the low DC voltage measurement at its inverter side. In this paper, the cause of the abnormal DC voltage elevation is analyzed based on the control strategy of Tian-Guang DC transmission system. A large number of RTDS simulation tests are conducted to investigate the over-voltage level and the response characteristics of the control and protection systems of the DC transmission system when DC voltage measurement at the inverter side is low in the cases of different grade of low DC voltage measurement fault,power level and operating mode. Simulation results show that low DC voltage measurement at the inverter side will result in overvoltage on DC system, the DC system will exhibit different control and protection performances at different fault levels, power levels and operating modes, and DC overvoltage level can be reduced in the case of high power mode and voltage-down operation mode.