有利于多馈入直流输电系统协调恢复的VDCOL控制策略研究

提出了一种适用于一般多馈入直流输电系统(MIDC)协调恢复的依赖于电压的电流指令限制单元(VDCOL)控制策略,该策略在各直流控制系统中综合应用不同类型的VDCOL控制,以改善逆变侧交流电网的暂态稳定性。对常规的VDCOL的特性曲线进行了改进,使得故障切除后的系统恢复期间直流电流的恢复滞后于电压的恢复,从而减小换流站无功消耗,促进交流换相电压的恢复。通过对南方电网的仿真研究表明,该控制策略对不同系统运行方式下的不同故障地点和类型具有较好的适应性,有效地提高了多馈入直流系统的暂态稳定性。

Study of VDCOL Control Strategies for Coordinated Recovery of Multi-feed-in HVDC System

A novel control strategy of voltage dependent current order limiter(VDCOL) for multi-feed-in HVDC systems is proposed in this paper. The strategy synthetically uses different kinds of VDCOL control in different DC control systems to improve the transient stability of the inverter side grid. Some modifications on VDCOL characteristics are applied to reduce reactive power consumption during low voltage situations. Simulation studies on the south China power grid show that,the proposed VDCOL control strategy can preferably enhance the transient stability of the whole power grid,especially when some serious ac faults occur close to inverter stations. Simulations also illustrate its robustness in response to various contingencies under various operation modes.