基于灵敏度分析的改进微电网下垂控制方法

传统下垂控制方法应用于微电网中存在电压和频率波动较大的问题,对此提出了一种基于灵敏度分析的改进下垂控制方法。由于微电网线路阻抗较大,基于灵敏度分析,在下垂控制中加入虚拟阻抗,调节了线路阻感比;并对下垂控制器进行改进使其具有更好的控制精度。将微电网的电压频率的误差与误差变化率作为模糊控制的输入量,运用模糊推理方法在线整定具有PI结构的下垂系数,从而控制电压与频率的输出。通过对微电网切换运行模式以及孤岛模式下切负荷这两种情况下的运行特性进行仿真分析,应用该方法不仅能平稳抑制电压幅值和频率的波动,还能在微电网切负荷之后合理分配各分布式电源(Distributed Generation,DG)的功率。仿真结果证明了该控制方法的可行性和有效性。

The improved droop control method of micro grid based on sensitivity analysis

The application of traditional droop control method in the micro grid would cause some problems of voltage and frequency fluctuations. Then, this paper proposes an improved droop control method based on sensitivity analysis. Because of the high line impedance of micro grid, the virtual impedance is added in the droop control method based on sensitivity analysis to adjust resistance-inductance ratio of lines. Meanwhile, the droop controller is improved for the better control accuracy. This paper takes error and error change rate of the micro grid voltage and frequency as the inputs of fuzzy control. In order to adjust voltage amplitude and frequency, the droop coefficient with PI structure is set online by fuzzy reasoning method. This paper analyzes the running characteristics of the switch between running modes and load shedding in islanding mode. Using this method can not only optimize those problems of voltage and frequency fluctuations, but also distribute power among these distributed generations after the load shedding. The feasibility and effectiveness of this control method is validated by these simulation results.