微网孤岛模式下负荷分配的改进控制策略

An Improved Control Strategy of Load Distribution for a Microgrid in Islanded Operation

考虑到微网线路阻抗呈阻性引起有功和无功之间存在强耦合,在孤岛模式下,采用传统V/f下垂控制策略不能有效地实现分布式电源输出功率随着负荷功率变化而变化,为实现负荷功率的合理分配,提出采用坐标旋转的虚拟功率V/δ下垂控制策略。该策略由于采用正交线性旋转变换矩阵,实现了功率的解耦,并且增加了功率输出限制反馈环节修正项和微分环节修正项,有效地跟踪负荷功率的变化,确保负荷的合理分配。通过对微网孤岛运行模式下增/切负荷或退出某一分布式电源进行Matlab仿真分析,验证所提出控制策略的可行性。

Considering an intensive coupling between the active and reaetive power because of resistive line impedance in microgrids, the generation units adopting traditional V/fdroop-control strategy can＇ t effectively achieve the distributed power source＇ s output power varies as the load power changes in island mode. The paper proposed a coordinate rotational transformation based on virtual power V/6 droop control strategy to achieving load distribution in islanded operation with distributed generation units. The strategy achieves the decoupled active and reactive power control through orthogonal transformation matrix, and the output power limiting measures feedback function and derivative function employs additional derivative terms with modified gain respectively, which guarantee stability and good transient response and load sharing in microgrid. The Matlab simulation results verify that the proposed control strategy is feasible for increasing or cutting load and cutting one distributed generator in islanded microgrids.