基于VSC-HVDC的线路过电压抑制策略研究

在电力系统发生大停电事故后的恢复过程中,控制启动方案中的重要因素即充电空载长线路时的工频过电压与合闸空载长线路时的操作过电压,分析了电压源换流器直流输电(VSC-HVDC)技术用于联网的优势,及由空载长线路电容效应引起的工频过电压与合闸空载线路引起的操作过电压的形成机理;提出利用联网的VSC-HVDC抑制空载长线路工频过电压与操作过电压的概念以及相应的过电压控制策略与系统并建立了联网的VSC-HVDC启动空载线路的数学模型。PSCAD/EMTDC仿真结果表明,VSC-HVDC能够有效抑制空载线路的工频过电压与操作过电压。

Study of Control Strategies of Suppressing Overvoltage on Overhead Lines by VSC-HVDC

During the restoration of black-out in the power system,the power frequency overvoltage caused by the capacitive effect of a non-loaded long overhead lines and the switching overvoltage by closing non-loaded long overhead lines are important factors to establish the restoration scheme.The mechanism developing the two kinds of overvoltage and the advantages applying HVDC using voltage source converter(VSC-HVDC) to grid interconnection were analyzed.The concept applying VSC-HVDC to suppress the power frequency overvoltage and switching overvoltage was developed,and the mathematical model using VSC-HVDC to start non-loaded long overhead lines was established.Meanwhile the control strategies and the corresponding control system of using VSC-HVDC to suppress the two kinds of overvoltage were developed through analyzing the mechanisms.PSCAD/EMTDC simulation results show that VSC-HVDC can effectively suppress the power frequency overvoltage and switching overvoltage on non-loaded long overhead lines.