基于DCT的真双极直流配电网电压-电流二级控制

在真双极直流配电网中，由于线缆阻抗的差异，底层传统下垂控制在实现较小的电压偏差和较高的分流精度时，存在着有矛盾，影响系统的稳定性和运行的经济性。为此，文中在底层控制的基础上提出一种基于DC/DC变换器(DC/DC transformer，DCT)的适用于真双极拓扑的电压-电流二级控制策略。该控制策略基于通信采集同极性并联DCT的电流和异极性串联DCT的电压，采用一致性算法使电流控制与电压控制均达到收敛，从而实现负荷的合理分配并有效抑制正负极电压的不平衡。在PSCAD/EMTDC平台中搭建真双极直流配电网模型进行仿真验证，仿真和评价结果验证了该控制策略在不同工况下的有效性、对不同拓扑的适应性及配网发生故障时的可靠性。

Secondary voltage and current control strategy based on the DCT in true bipolar DC distribution network

In the true bipolar DC distribution network,due to the difference in cable impedance,the traditional bottom droop control has inherent contradictions between reducing voltage deviation and improving shunt accuracy,which affect the stability of the system and the economy of operation. Based on the underlying control,a voltage-current secondary control strategy based on DC/DC transformer (DCT) suitable for true bipolar topology is proposed. The control strategy is based on communication to collect the current of parallel DCT and the voltage of series DCT with different polarity. The consistency algorithm is adopted to achieve convergence of current control and voltage control, thereby achieving the optimal load distribution and effectively suppressing voltage imbalance. A true bipolar DC distribution network model is built by PSCAD/EMTDC. The simulation and evaluation results verify the effectiveness in diverse working conditions,adaptability to different topologies and reliability when a fault occurs in a distribution network of the proposed control strategy.