该文提出一种应用P/w(Q/E)“导纳”的逆变器无线并联系统稳定性分析方法。该方法将每台并网逆变器的功率控制模型等效为一个“开路电压”和一个“导纳”倒数串联的二端网络,从而得到整个并联系统的模型。理论分析表明,并网模式下,系统的稳定性由系统中每一个“导纳”的稳定性决定,而孤网模式的稳定性由并联网络中所有“导纳”和的倒数的稳定性决定。进一步研究,该文得出两个关于孤网并联系统设计的实用性结论,该结论指出当并联系统中各逆变器具有相同或成比例关系的“导纳”时,孤网系统的稳定性取决于该“导纳”的稳定性。仿真与实验均验证该文提出的研究方法和所得结论的可行性与正确性。
A method using a P/w(Q/E) "admittance" for the stability analysis of wireless parallel-inverter systems was proposed. Power control of each inverter was deduced to be a two-terminal network where one "open-circuit voltage" connects in series with one "admittance" reciprocal, thus, the power model of the whole parallel system can be obtained. Through theoretical analysis, the stability for the grid-connected mode is determined by each "admittance" in the network, while the stability for the stand-alone mode is determined by the reciprocal of the sum of all the "admittances". Furthermore, two practical conclusions used for the design of the stand-alone system were obtained by this method. It is pointed out that, if all the parallel inverters have the same or proportional "admittance", the stability of the stand-alone system is determined by the stability of the "admittance". Simulation and experimental results are given to validate the proposed method for the stability analysis of the parallel inverter system and the practical conclusions.