Impact of Energy Management of Electric Vehicles on Transient Voltage Stability of Microgrid

There is cause and effect relationship between increase in load due to increasing penetration of electric vehicles (EV) load that causes unbalanced conditions and affect the power quality such as voltage degradation and even damage the equipment if the system is not properly managed. This paper presents detailed review of energy supply and management in conjunction with load synchronization through EVs for maintaining transient voltage stability by providing reactive power support for the stability of power grid in vehicle-to-grid mode of operations. The energy management system is considered at different levels such as, stand-alone PV, stand-alone wind, stand-alone battery storage, stand-alone EV parking lot, residential feeder and commercial building feeders. First we proposed energy management algorithm, to limit the peak power drawn by EVs from distributed energy resources of microgrid, such that additional electrical resource will be transferred to resource constrained devices. The EVs negotiate based on their demand, priority and available electrical resource such that during higher electricity price the higher priority vehicles still require resource and perform uninterrupted operation. The transfer of electrical resource from one load device to another will help in reducing peak demand and improving the efficiency of the system. Secondly we proposed transient voltage stability margin index (TVSMI) to test the capability of EVs in contributing storage and supply services to the grid. The energy management control simulations are realized in DIgSILENT Power factory.