可变拓扑的改进型交直流混合微电网

为提高配电网非理想工况下并网的交直流混合微电网(HMG)的运行性能，提出一种可变拓扑的交直流HMG及其控制策略。首先，在HMG交流母线与配电网之间插入了串联补偿变压器(SCT)，并设置对应的双功能变换器在并网运行时控制SCT实现电压补偿，而在孤岛运行时用作HMG交直流母线接口变换器。其次，在分析电路拓扑和工作模式的基础上，设计了双功能变换器与交直流母线接口变换器的解耦协调控制策略。最后，仿真和实验结果表明，在配电网电压波动、暂降和暂升工况下，所提方案能够使HMG交流母线电压保持稳定，提高了HMG的故障穿越能力和供电质量。

An Improved Hybrid AC/DC Microgrid with Variable Topology

In order to improve the grid-connected operation performance of the hybrid AC/DC microgrid (HMG) in non-ideal distribution network environment, this paper proposes an improved HMG with variable topology and its control strategies. First, a series compensation transformer (SCT) is inserted between the AC busbar of the HMG and the distribution network, and the corresponding dual functional converter is set to control the SCT to realize voltage compensation in the grid-connected operation mode, while it is used as an AC/DC busbar interface converter of the HMG in the island operation mode. Then, based on the analysis of the circuit topology and operation modes, the decoupled and coordinated control strategies of the dual functional converter and busbar interface converter are designed. Finally, the simulation and experimental results show that the proposed schemes can keep the AC busbar voltage of the HMG stable and improve the fault ride-through ability and power supply quality of the HMG under conditions of voltage fluctuation, sag and swell.