Hierarchical Coordinated Control of Electric Vehicle Parking Lot in Distribution System

Abstract

Uncoordinated charging of EVs may result in overloading, increased losses and voltage deviations in distribution system. In this context, coordinated charging of EVs by parking lot operator (PLO) is a potential solution these problems. PLO coordinates charging of EVs during low electricity prices to avail monitory benefits. However, charging of EVs during low electricity prices results in unusual peaks which may adversely affect the operation of distribution system. Therefore, coordinated scheduling of EVs by PLO considering operational constraints of distribution system is essential. To this end, this study proposes a hierarchical framework of coordination between PLO and distribution system operator (DSO) for scheduling of EVs. In the hierarchy, PLO coordinates the charging demand of EVs to minimizing the charging cost. Thereafter, optimal operation of distribution system is considered at DSO level with EVs load demand obtained from PLO. If the operational constraints of distribution system are violated, DSO determines the load boundaries for EVs load and communicates to PLO. Finally, PLO allocates the charging demand to EVs considering the load boundaries suggested by DSO. The proposed methodology is validated on 33-bus radial distribution system. Simulation results indicate that proposed approach results in efficient operation of distribution system while minimizing charging cost to PLO.