主从结构微电网并网/孤岛运行模式平滑切换控制策略

Smooth Switching Control Strategy for Grid-connected and Islanding Operation Mode of Microgrid Based on Master-slave Structure

摘要:

对于主从控制结构的微电网系统，如何抑制切换过程中电压、频率的振荡，实现并网/孤岛运行模式间的平滑切换是一项亟待解决的技术难点。针对微电网并网/孤岛运行模式电压与频率的动态特性，提出一种基于并行运行与数值缓启动器的平滑切换控制策略。并行运行通过同步运行PQ控制与V/F控制策略，抑制了模式切换过程中的电流波动。数值缓启动器则平滑了电流内环的输入给定值，减小了切换过程中瞬时冲击电流对电流内环的影响，抑制了微电网模式切换过程中母线电压与频率的振荡。最后，基于Matlab/Simulink建立光储微电网系统，在并网/孤岛模式切换与负荷加载等工况下进行仿真实验，验证了所提平滑切换控制策略的有效性。

关键词:微电网; 主从结构; 并网运行; 孤岛运行; 平滑切换

Abstract:

Addressing the critical technical challenge of mitigating voltage and frequency oscillations during the transition between grid-connected operation and islanding operation modes in microgrid systems with a master-slave control structure is imperative. Focusing on the dynamic characteristics of voltage and frequency during microgrid grid-connected operation and islanding operation mode, a smooth switching control strategy is proposed based on parallel operation and numerical soft starter. Through the synchronized PQ control and V/F control, the parallel operation effectively suppresses current fluctuations during mode transitions. And the numerical soft starter plays a crucial role in smoothing the input reference values for current inner loop, and reducing the impact of transient impulse current on current inner loop during switching process, which suppresses the oscillations of bus voltage and frequency during microgrid mode switching. Finally, a model of photovoltaic-storage microgrid system is constructed using Matlab/Simulink, and the simulation experiments, covering scenarios such as grid-connected/islanding mode transitions and load variations, verify the effectiveness of the proposed smooth switching control strategy.

Key words:microgrid; master-slave structure; grid-connected operation; islanding operation; smooth switching