适用于不同等效阻抗的并联逆变器环流抑制方法研究

Study on restraint of circulating current in parallel inverters with different equivalent impedance

对于配电网中的并联逆变器电源,需要对其进行合理的功率分配,并抑制系统环流。针对等效阻抗、并联逆变器额定容量不同的情况,提出了一种适用于不同等效阻抗的并联逆变器环流抑制方法。利用逆变器的输出电压幅值和相位解耦控制框架,分析了具有下垂控制特性的逆变器输出的有功功率和无功功率复域表达式。进而,对无功功率控制环节进行改进,增加了积分环节,改善了无功功率控制受等效阻抗波动的影响。同时提出一种改进下垂控制策略,根据实际功率情况自适应调节电压和频率下垂系数,使其更好地满足多并联逆变器功率分配和环流抑制的要求。

It needs to distribute power reasonably and restrain circulating current in parallel inverters of distribution network.According to the situation of different equivalent impedance and rated capacity, a method of restraining circulating current in parallel inverters with different equivalent impedance is proposed. Using decoupling control structure of output voltage amplitude and phase, active power and reactive power complex domain expression of parallel inverters with droop control feature. Then, to reduce the problem that the control of reactive power is affected by fluctuation of equivalent impedance,controlling unit of reactive power is improved by adding integration element. According to actual power situation, a strategy of improving droop control is proposed by adjusting droop coefficient of voltage and frequency, it can better satisfy the requirement of power distribution and circulating current restraining in parallel inverters.