主从控制混合微电网中互联变流器控制策略

针对基于主从控制的交直流混合微电网，研究了孤岛模式下的功率平衡关系和互联变流器控制策略。主控制单元控制系统的功率波动，维持系统的稳定性，因此提出了主控制单元容占比的概念，来反映两侧微电网的运行状态；根据此概念，建立了交直流两侧的数学联系，设计了互联变流器的分区段控制策略，调节功率在微网间的流动，以实现两侧功率的相互支撑；为了避免互联变流器运行模式的频繁切换，设置了滞回比较环节，提高系统的稳定性。在PSCAD／EMTDC搭建了交直流混合微网仿真模型，结果表明，在孤岛模式下分区段控制策略能够实现对互联变流器的灵活控制，可准确调节交直流子网间的功率流动，实现系统的功率平衡以及各微网的电压和频率稳定。

Control Strategy of Inter-linking Converter in Hybrid Microgrid Under Master-slave Control

This paper studies the power balance relationship and control strategy of the inter-linking converter in hybrid AC/DC microgrid in island mode under master-slave control. The main control unit bears the power fluctuation and maintain the stability of the system. The concept of capacity occupancy rate of main control unit is proposed to reflect the operation state of hybrid microgrid on both sides. According to this concept, the mathematical connection between AC and DC is established, and a partitioning control scheme for inter-linking converter is designed, which can regulate the power flow between the microgrid and achieve mutual power support between the two sides. In order to avoid the inter-linking converter switching frequently among different operation modes，hysteresis comparison is set up to improve the stability of control system. Simulation of hybrid AC/DC microgrid in PSCAD/EMTDC shows that, the control strategy of partition can realize the flexible control of the inter-linking converter and adjust the power flow between AC and DC microgrids accurately, which is helpful to realize power balance in the hybrid microgrid and maintain the stability of each sub-microgrid.