Research on Initialization of EMT Simulation for Photovoltaic Grid-Connected System

Abstract

In this paper, an improved steady-state initialization method is proposed for electromagnetic transient analysis of photovoltaic grid-connected system, which enables an EMT simulation to start from steady-state directly. The improved method is based on power flow solution, and it determines the steady state operating characteristics of the system network from the given line and bus data. Then, based on the power flow, the ac system and the filter steady state are obtained by replacing converter bridge with a three-phase voltage. Furthermore, in consideration of the control system steady state, the PI controller initial values are set as the steady state values. EMT simulation for the photovoltaic grid-connected power generation system with 6-bus is performed on Cloud-PSS platform. Comparing with the traditional zero-state initialization method, the proposed method has faster response and smoother transient with necessary accuracy.