Investigation In Voltage Regulation Method For Microgrids Containing Electric Vehicles

Nowadays,the problem of resource and environment is more and more serious,so the rapid development of microgrid technology containing electric vehicles(EVs)is drawing more and more attentions.The fluctuation of voltage in microgrids is significant due to the randomly fluctuating output power of wind turbines(WT)and photovoltaic(PV)generators,especially in the islanded operation mode.Therefore,voltage regulation in microgrids faces great challenges.For microgrids containing electric vehicles(EVs),coordinated charging/discharging of electric vehicles(EVs)can be used.This paper investigates the voltage regulation in microgrids containing electric vehicles,PVs and WTs.Bidirectional flow of EVs' energy is made use of to make EVs coordinate with PVs and WTs and to keep voltage of the microgrid in stability with static storage devices decreased.The main innovation contributions are as follows:(1)An optimal model of voltage regulation is established.In this model,the fluctuation of the node voltage is regarded as objective function,and power of EVs,loads and DGs are regarded as control variables.Power of renwable energy can be curtailed if necessary.Constraints include limits of power and voltage and so on.In order to satisfy the charging demand of EVs,the constraint of EVs' schedulable capacity is added into the optimal model.And the power of individual EVs is scheduled according to the schedulable capacity rate at any time slot.(2)A distributed method based on gossip algorithm is proposed aimed at the model.By this method,the respective optimization problem is solved locally by applying the gossip algorithm where the necessary global information such as power and voltage of all nodes is derived by exchanging local information with neighboring nodes via smart meters.So,voltage regulation can be achieved without Microgrid Central Controller.(3)Siemens Benchmark 0.4kV microgrid containing PV,WT,battery(BT),EVs and micro turbine(MT)is used as a tested microgrid,to verify the proposed method.Both the grid-connected and islanded operation mode are simulated.The simulation results show using the proposed method,the node voltage in the microgrid can be regulated effectively in both operation modes.And the proposed method is more effective than the centralized method.