含潮流控制器的多端柔性直流配电系统协调优化

Coordination Optimization for Multi-terminal Voltage Source Converter Based Direct Current Distribution System with Power Flow Controller

当多端柔性直流配电系统发生功率扰动、换流站过载或停运时,直流网络的潮流分布将呈现非线性变化,可能导致线路过载或节点电压越限。为此,提出一种换流站与直流潮流控制器(DCPFC)共同参与调节系统潮流的协调控制策略,以各工况下网损和电压偏移最小,建立多目标优化模型。首先,考虑换流站下垂控制的局限性,通过灵敏度法指出DCPFC可减小电压偏移。然后,提出了含DCPFC的多端柔性直流配电系统最优潮流(OPF)模型,自适应修正下垂系数与DCPFC的控制参数。最后,推导了各工况下网损与电压偏移的解析表达。对四端柔性直流配电系统的仿真结果证实了所提控制策略的有效性。

The power flow distribution in the multi-terminal voltage source converter(VSC) based direct current distribution system changes nonlinearly with the power disturbance,overload or outage of the VSC,which possibly causes overload or over-voltage. A coordinated control strategy for the VSC and the direct current power flow controller(DCPFC) is proposed, and the multi-target optimization model with the objective function of the minimum network loss and the minimum voltage deviation under various conditions is derived. Firstly,considering the limitation of the droop control of the VSC,it is described by the sensitivity method that the DCPFC may reduce the voltage deviation. Then,the optimal power flow(OPF) model for the multi-terminal VSC based direct current distribution system with the DCPFC is proposed,and the control parameters of the VSC and the DCPFC are adaptively adjusted. Finally,the analytical expressions of the network loss and the voltage deviation under various conditions are proposed. The numerical results on the four-terminal VSC based direct current distribution system validate the effectiveness of the proposed control strategy.