Study on the influence of large-scaled electric vehicle dispersed charging on transient voltage stability of distribution systems

As large-scaled electric vehicles (EVs) connecting to power distribution system via charging devices, the load of power system will get heaver in the foreseeable future. This will lead to an increasing risk for the security and stability of operation. Studying the quantitative influence that EV charging loads bring to the transient voltage stability of distribution system is of vital significance to analyze the security and stability status of power system after large-scaled EV loads are connected. Considering the torque-slip property of induction motor load, an index represented by relative value of slip considering induction motor loads is proposed in this paper, aiming at indicating the margin of transient voltage stability of distribution network. Furthermore, simulation analysis and calculations are carried out to study the transient voltage instability condition, and the focus of this paper is on the dispersed charging scenario of large-scaled EVs. The result shows that the index proposed is capable of reflecting the profound effect of large-scaled EV loads on the transient voltage security of distribution network.