Influence of Parameters Non-uniformity on Inverters Dynamic Equivalent Error

Abstract

The influence of parameters non-uniformity including various controller, power levels and network parameters on multiple grid-connected inverters dynamic equivalent error are investigated. The error is divided into two parts. One part is caused by the inconsistent recovery time of inverters at different power levels during low voltage ride-through (LVRT), and the other is attributed to the different dominant dynamics of the inverters. According to these two sources of error, a two-step clustering method is proposed and implemented in a 36-inverter system. The simulation results show that this method has higher precision in different scenarios, but it is accompanied with the sacrifice of simulation speed. Then, the simulations of a 6-bus system show that the error of the single inverter equivalence become large when crowbar acts, and the impact of the first type of error is significantly greater than the second one.