用于微网逆变器并联的控制策略

对于包含多个逆变器的微电网系统,使用传统下垂控制法会造成逆变器间环流及功率分配不均,这是由于逆变器的输出阻抗及线路阻抗各有差别。首先介绍了传统下垂控制方法,并以此分析逆变器输出阻抗为阻性时的功率分配情况,指出传统下垂控制的缺陷。随后,为了达到功率精确分配及等效输出阻抗为阻性的要求,即满足能够正确使用传统下垂控制法的前提条件,引入满足条件的阻性虚拟阻抗,并给出该虚拟阻抗的具体添加位置。至于输出电压偏差,可以通过在传统下垂控制法中添加电压反馈环节来予以解决。最后,仿真结果表明了该改进下垂控制策略的正确性和有效性。

A Control Strategy for Parallel Operation of Multi-inverters in Microgrid

Since the output impedance of the inverters and common connection point areSdifferent, for multi-inverter parallel micro-grid system, the application of traditional droop control method will lead to increased circulation andSuneven distribution among paralleled power inverters. In this paper, firstly, traditional droop control method and the impact of output impedance are analyzed. Then it finds out the inherent limitations of the conventional droop control scheme. So to overcome the shortcomings of traditional droop control method, it introduced resistive virtual impedance , both changes the properties of equivalent output impedance and brings précised power sharing of the parallel-operated inverter in Microgrid. Additional of voltage fed back in traditional droop control can solve voltage deviation. Simulation results demonstrate that the control strategy is correct and effective.