线路阻抗不等的微网改进下垂控制策略

Improved Droop Control Strategy of Microgrid Considering Unequal Line Impedance

微网孤岛运行时通常采用下垂控制策略,负荷有功及无功功率可根据下垂系数在各个逆变器之间按比例分配。但当线路阻抗不一致时,逆变器输出无功功率会因线路阻抗影响而存在较大偏差。为使逆变器输出无功功率按规定比例分配,提出一种无功功率按需分配的下垂系数计算方法,利用线路阻抗、额定电压等参数计算得到下垂系数,使无功功率按设计比例分配;同时进行小信号稳定性分析及仿真、实验验证,分析及实验结果验证了下垂系数选择方法的准确性。

Droop control is used when microgrid operates in island mode.The output reactive powers of distributed generation units will be allocated inaccurately because of unequal line impedance.In order to alleviate uneven sharing of reactive power,a selection method of droop control parameters is proposed.Some fixed parameters such as line impedance,nominal voltage is used to ealeulate the droop control parameter so as to make reactive power share accurately.Simulation and experimental results demonstrate the accuracy of the selection method.