基于改进下垂控制的逆变器并联运行技术

为了实现逆变器并联系统中负荷功率的合理分配,针对输电线路阻抗不同的情况,给出一种基于逆变器输出端电压调节的改进下垂控制方案。利用逆变器参考电压幅值与其输出功率的关系,粗略调节其参考电压的幅值,针对该环节导致的电气波动量大的问题,加入通过下垂系数调节逆变器输出端电压的微调环节。利用该方案对通过不同输电线路并联的两台同容量逆变器进行仿真,并与采用传统下垂控制方案的结果进行比较分析。仿真结果表明,改进下垂控制方案不但能够保证并联逆变器之间的负荷功率均分以及优质的电能质量,而且系统环流小。

Parallel operation technology of inverters based on improved droop control

When the transmission line impedances are different, traditional droop control is difficult to realize reasonable load power sharing in parallel inverters. Thus, an improved droop control scheme based on inverters output voltage adjustment is presented. Reference voltage amplitude of each invrter is adjusted roughly by using the relationship between it and the output power. Since it leads to much electrical fluctuation, an output voltage minute adjustment by drooping coefficient is added. Two inverters with the same capacity and different line parameters are carried out, and simulation results using the traditional and proposed schemes are compared and analyzed. The results show that the proposed scheme achieves power sharing and good power quality, and the circulating current is small.