连接VSC-HVDC的弱电网低频振荡研究

摘要

The inverter station of VSC-HVDC is modelled as a synchronous generator when con-nected to a weak grid.In order to increase the moment of inertia,the virtual inertia control mode is used.The moment of inertia for the weak grid can be increased and the dynamic frequency for receiving end grid can be provided.In this case,a problem of low frequency oscillation phenome-non may occur due to the negative damping effect of the power system,which causes the system un-stable operation.In this paper,the theory on low frequency oscillation of the weak grid con-nected to VSC-HVDC was analyzed.A method of increasing the damping coefficient at inverter was adopted to avoid low frequency oscillation.PSCAD/EMTDC based simulation was carried out.Results showed that the proposed method can effectively inhibit the low frequency oscillation when VSC-HVDC is connected with a weak grid.%电压源换流器型的高压直流输电连接弱电网时,逆变站采用虚拟转动惯性控制方式,将VSC-H VDC的逆变站模拟为同步发电机以增加受端交流系统的转动惯量,为受端电网提供动态频率支持.受端电网可能会因为电力系统的负阻尼作用产生低频振荡现象而造成系统不能正常稳定运行.理论分析了VSC-H VDC连接弱电网的低频振荡问题,提出采用增大逆变站阻尼系数的方法抑制弱电网的低频振荡.利用PSCAD/EMTDC软件进行仿真,结果表明所采用的方法能够较好抑制此情况下弱电网的低频振荡.