VSC-HVDC输电系统模式切换控制策略

摘要

Mode switching control strategy of voltage source converter based high voltage direct current（VSC-HVDC） transmission system under AC system fault of DC voltage control side is analyzed.A mode switching control based on hysteresis loop and local DC voltage detection is proposed and implementation of this method is given.Relationship between DC power and voltages of both sides under steady state is then derived and a method for calculating DC voltage working range of active power control converter is given.Based on these approaches,a method for determining DC voltage thresholds and references in the mode switching control strategy is proposed.Finally,simulations in PSCAD/EMTDC are conducted to verify the validity of the mode switching control strategy under various faults and operating state.Results show that this determination method can provide mode switching control strategy of VSC-HVDC system with a reliable and accurate reference.%分析了基于电压源换流器的高压直流（VSC-HVDC）输电系统在定直流电压控制端交流电网故障下的模式切换控制策略,提出了基于滞环和本地直流电压检测的模式切换控制,并给出了该控制的实现方法。推导了正常运行时VSC-HVDC输电系统直流功率与两侧换流器直流电压的关系式,给出了定有功功率控制端的直流电压正常工作范围的计算方法,提出了模式切换控制策略中直流电压阈值和故障穿越期间直流电压参考值的确定方法。最后,PSCAD/EMTDC仿真验证了在不同故障类型和不同运行方式下VSC-HVDC输电系统模式切换控制策略的有效性;仿真结果表明,该直流电压阈值和参考值的确定方法能够为模式切换控制策略的指令值整定与配合提供可靠参考。