基于多控制复杂度下的交直流微电网无缝切换

Seamless Switching of AC-DC Microgrid Based on Multi-Control Complexity

对等控制下的交直流混合微电网,其并网逆变器随着运行状态的改变会切换不同的控制方式,不同的控制方式切换时,会存在电压、频率、电流等电量瞬态突变的问题,导致微电网无法平稳运行.为实现孤岛与并网两种模式间的无缝切换,本文设计了一种基于下垂控制和PQ控制的软切换复合控制策略,将两种控制方式的电流内环进行耦合,构成一种基于电流跟踪的双模组合控制器,使输入电流内环控制器的参考电流能够跟踪切换时刻之前的状态,且保持正确的初始值,并设计了对频率、相位、幅值的补偿预同步控制策略,使微电网孤岛/并网模式平稳切换。通过PQ控制使有功交换功率P和无功交换功率Q为0,使大电网侧和微电网的交换功率为0,实现了并网/孤岛模式的切换。最后在MATLAB/Simulink中验证了该控制策略的有效性和可行性。

In the hybrid AC-DC microgrid under peer-to-peer control,the grid-connected inverters will switch different control modes with the change of operating status.When different control modes are switched,there will be transient changes in voltage,frequency,current and other power levels,resulting in the microgrid unable to run smoothly.In order to realize seamless switching between islands and grid-connected modes,a soft switching composite control strategy based on sag control and PQ control is designed in this paper,and the current inner loop of the two control modes is coupled to form a dual-mode combined controller based on current tracking,so that the reference current of the input current inner loop controller can track the state before the switching time and maintain the correct initial The initial value and the compensated pre-synchronization control strategy for frequency,phase and amplitude are designed to make the microgrid island/grid-connected mode switch smoothly.Through PQ control,the active switching power P and reactive switching power Q are O,and the switching power of the large grid side and the micro grid is O,and the grid-connected/island mode is switched.Finally,the effectiveness and feasibility of the control strategy are verified in MATLAB/Simulink.