基于三电平变流器的光伏微电网及其控制策略研究

孤岛运行的微电网常常具有可再生能源发电量时变、负载时变、三相不平衡等特点，为解决微电网的电能质量﹑稳定性等问题，本文提出适用于光伏微电网的三电平变流器结构及其电压内环，有功功率和无功功率调节为外环的控制策略。多机并联运行时，采用公共同步脉冲与均流解耦控制策略实现微电网全网范围内的变流器单机虚拟磁链的旋转同步。仿真和实验都证明了控制策略简单可行，电能性能指标比传统变流器优越，为四桥臂三电平双向变流器的开发提供理论基础、实验依据。

The Control Strategy of PV Microgrid Based on Three-Level Converters

The microgrid in islanding possesses characteristics such as renewable energy generation fluctuation, load change and three-phase voltage unbalance. In order to solve power quality and stability problems in microgrid, this paper focus on the three-level converter structure and its control strategy consisted of inner voltage controller and outer active/reactive power controller for photovoltaic microgrid. For multimachine parallel operation, single converter virtual flux rotation synchronization in the whole system is achieved by network public sync pulse and current sharing decoupling control strategy. Simulation and experiment results demonstrate that the proposed control strategy is simple and feasible, and the power quality is improved compared to the conventional converter. It also provides theoretical and experimental guidelines for the development of the four-leg three-level bi-directional converters.