并联微网逆变器输出功率精确分配研究

为了解决基于传统下垂控制的并联微网逆变器输出功率分配不合理问题,以两逆变器并联运行模型为研究对象,详细分析下垂控制中并联逆变器输出功率分配机理,得出并联逆变器输出功率分配不精确的本质原因是逆变器总输出阻抗和额定容量间的不匹配。进而提出了一种改进下垂控制策略,在电压外环采用准比例谐振(PR)控制,同时虚拟阻抗被引入到电流反馈环,进而使逆变器总输出阻抗近似于虚拟阻抗,通过比例设置虚拟阻抗实现并联逆变器输出功率的精确分配。此外,在功率控制环中引入逆变器输出电压幅值反馈环节,合理选定预设电压,有效改善了虚拟阻抗造成的输出电压降低问题。仿真软件验证了理论分析的正确性。

Research on accurate output power distributed of parallel microgrid inverter

In order to solve the problem of unreasonable output power distribution of parallel microgrid inverters under traditional droop control, this paper takes parallel operation model of two inverters as the research object, Detailed analysis of the output power distribution mechanism of parallel inverters in droop control, and the essential reason for inaccurate output power distribution of parallel inverters is the mismatch between the total output impedance of the inverter and the rated capacity. Therefore, an improved droop control strategy is proposed to solve this problem. The quasi-proportional resonance (PR) control is applied to the outer voltage loop, and the virtual impedance is introduced into the current feedback loop, so that the total output impedance of the inverter is similar to the virtual impedance, thus achieving accurate distribution of output power of parallel inverters by setting virtual impedance according to capacity ratio. In addition, introducing the inverter output voltage amplitude feedback loop into the power control loop and properly selecting of the predetermined voltage can effectively improve the output voltage reduction caused by the virtual impedance. the validity and feasibility of the theoretical analysis are verified by simulation software.