SYNCHRONOUS STABILITY ANALYSIS AND OPTIMIZATION STRATEGY OF LVRT FOR GRID-CONNECTED INVERTER
To address the problem that the existing low voltage ride-through(LVRT)studies cannot accurately and comprehensively assess the synchronous operation capability of converters,the effects of different factors on the quasi-static equilibrium point are quantitatively investigated by combining the LVRT characteristics and the grid-side characteristics,and the existence conditions of the quasi-static equilibrium point of the system are revealed.The influence of LVRT characteristics on the transient stability and small-signal stability of grid-connected inverters is analyzed,and it is clarified that the system not only has the risk of transient loss of synchronization during grid faults but also is difficult to operate stably at the quasi-static equilibrium point.Based on the above theoretical analysis,an optimization strategy for improving the LVRT synchronous operation capability of grid-connected inverters is proposed.The strategy adaptively adjusts the phase-locked loop parameters according to the grid operation state during LVRT,which not only reduces the risk of system transient loss of synchronization but also enhances its small signal stability margin.Finally,the correctness of the theoretical analysis and the effectiveness of the optimization strategy is verified by simulation and experiments.
invertertransient stabilityphase locked loopsmall-signal stabilityquasi-static equilibrium point
NETL
NSTL
万方数据
维普
