多逆变器并联并网系统稳定性分析

STABILITY STUDY OF MULTI-PARALLEL INVERTER SYSTEM

实际工程中多逆变器并联并网系统中的各逆变器之间往往存在一定差异,为研究逆变器参数不统一的多逆变器并联并网系统的稳定性及谐振机理,以逆变器参数不统一的一般性多逆变器并联并网系统为研究对象,将系统分解为导纳网络和激励源两部分,分别推导出系统中不同逆变器之间以及逆变器与电网之间的相互作用电流,据此揭示出这些不同元件之间的相互作用机理,提出一种根据导纳网络和逆变器自身的稳定状态来判断系统稳定性的方法。利用上述不同元件之间的相互作用电流分量合成逆变器输出电流以及并网电流,并推导出其稳定性判定条件,最终得到一种具有一般适用性的多逆变器并联并网系统稳定性判定方法。仿真及实验结果可验证理论分析的正确性。

Most of the existing relevant literatures are focused on the multi-inverter system where inverter parameters are identical. Till now,the stability analysis for the system consisting of polytype inverters is still not mature. In terms of the above issues,the paper focuses on the multi-inverter system where inverter parameters differ. The system is decomposed as the admittance network and the excitation sources. The interaction current between any two different inverters and between the inverter and the power grid are deduced,according to which the interaction mechanism between different components is revealed. Then a stability analysis method based on the admittance and the inverter stability is proposed. The inverter current and the grid current are composed with the above interaction components,based on which their stability criteria are also obtained. In the end the commonly used stability analysis method for the multi-inverter system is derived. The theory analysis is verified by the simulation and experiment results in the paper.