基于动态下垂系数的微网下垂控制策略

Microgrid Droop Control Strategy Based on Dynamic Droop Coefficient

传统下垂控制中下垂系数为常数,下垂系数小则动态响应慢,下垂系数大则频率和电压可能会远远偏离参考值,且难以保证微网的稳定性。针对这一问题提出了一种基于动态下垂系数的改进下垂控制策略。改进下垂控制通过截取平移和伸缩后的正弦函数在二、三象限的函数曲线作为下垂控制特性曲线,使用此方法可以保证微源的输出频率和电压始终维持在设定值范围内,且在参考功率附近有较大的下垂系数,从而实现微源的有效出力。随着输出功率远离参考值,微源出力减弱,下垂系数会随正弦函数减小,从而防止微源出力过调。最后分别进行仿真和实验,并与传统下垂控制策略模型相比较,结果验证了该策略的可行性。

The droop coefficient is constant in the traditional droop control, if it is too small then the dynamic response is slow, otherwise the output frequency and voltage may deviate far from the reference value, it is difficult to ensure the stability of the microgrid. To solve this problem, an improved droop control strategy based on dynamic droop coefficient was proposed. The improved control strategy interceped the sine function curve in the two or three quadrants as the droop control characteristic curve. Using this method can ensure that the output frequency and voltage of the micro source are always maintained within the reference value, and the value of droop coefficient is large near the reference power, so as to realize the output power of micro source. As the output power is away from the reference value, the output of the micro source weakens, the droop coefficient decreases with the sine function, thereby preventing the micro source output power from being excessively adjusted. Finally, the simulation and experiment were performed respectively, and compared with the traditional control strategy model, the results verified the feasibility of the improved strategy.