引入功率微分项下垂控制的微电网小信号稳定性分析

Small-signal Stability Analysis of Microgrid Using Droop Control with Power Differential Term

微电网一般采用下垂控制实现功率分配,但易产生受扰振荡。在下垂方程中引入功率微分项能够有效抑制振荡。建立了引入功率微分项前后的微电网系统的小信号模型,对比分析了控制参数与线路参数变化对系统小信号稳定性的影响,总结了控制参数的选择方法。并进一步地进行了灵敏度分析,研究对比了微电网中各逆变电源状态变量对系统低频模态的参与程度,以及线路参数变化对参与因子的改变。得出结论:线路长度或阻抗比增加为系统提供阻尼,且越靠近该线路的逆变电源获得的阻尼越大;且使用下垂控制时,系统特征根对各逆变电源的主导性更易改变。最后,通过不同工况下的仿真验证了建模、分析与结论的正确性。

Generally, droop control is used to achieve power distribution in microgrid, but it is easily to produce oscillation under disturbances. Adding a power differential term in droop equations is an effective way to suppress the oscillation. In this paper, microgrid small-signal models of the conventional droop control and the power differential droop control are established. The small-signal analysis is presented to identify the relationship between the controller parameters or the line parameters and the system stability. And the methods for selecting control parameters are summarized. Then, the sensitivity analysis is presented to contrast the degree of participation of state variables in the low frequency modes. And the association between the line parameters and the participation factors is studied. The conclusion is that the system damping increases with the increase of length or impedance ratio of line. And the dominance of eigenvalue on each inverter source is easy to change. Finally, simulation results in different conditions are used to verify these.