一种并联分布式微源的无功功率均分控制策略

A control strategy of reactive power sharing for parallel distributed micro-sources

在微电网多逆变器并联系统中,由于各逆变器之间的输出阻抗和馈线阻抗存在差异,因此,应用传统的下垂控制策略会导致逆变器间无功均分精度较低而造成环流问题。为了减小环流、提高无功分配的精度,提出一种改进型下垂控制的微电网无功均分策略。该方案利用低带宽通信获取各微源的无功功率信息,修改无功电压下垂特性曲线的电压偏置,达到提高无功出力分配精度的目的。同时,所提出的环流和负荷电压偏差为优化指标的目标函数,优化并设计控制参数。研究结果表明:改进的无功均分方法在不影响有功功率均分的条件下,极大提高了微源无功功率均分的精度,并具有良好的动态和稳态性能。

For multi-inverters parallel operation in microgrid, the output impedance of inverters and the line impedance between the inverters and point of common coupling are always different, which can result in big circulating current and low precision of power sharing among inverters by using the traditional droop control method. To reduce the circulating current and improve the reactive power sharing accuracy, a novel droop control strategy of reactive power sharing was proposed. The method with low bandwidth communication was employed to modify the voltage bias of reactive power-voltage droop characteristic, so that the reactive power sharing accuracy can be improved. The objective function was proposed with the optimization index of circulate current and load voltage deviation, and the system parameters were optimized and designed. The results show that the improved droop controller can achieve load reactive power precisely without affecting the active power sharing, and it also has a good dynamic and steady-state performance.