Research On Vehicle-to-grid With The High Penetration Rates Of Microgrids

In order to make the electric vehicles widely used, many countries are building lots offacilities to charge, making the electric cars more convenient to access the power system.However, holding the extra load of electric cars will pose a big challenge to the bearing ability ofthe current power system. The microgrids are to become the power supply ends of main grid, andthey are usually connected to the low voltage distribution network, which will be thedevelopment trend of the future power grid. Since the electric cars are charged in the low voltagedistribution network in general, so the electric vehicles can be managed by the microgrids.Electric vehicles have great potential in reducing environmental pollution and transportation cost,research on the Vehicle-to-Grid (V2G) has become a hotspot recently. Using V2G, the vehiclescan make the best use of their on-board energy storage equipments to interchange energy withthe grid, support the large-scale application of renewable energy, and improve the efficiency andstability of the electric power system. The technology and its application can make the grid andthe vehicle transportion closely, and they could be the effective means to solve the current crisisof energy and environment, so smart grid and microgrids could offer good environment for themto plug in.With the electric vehicles and microgrids grew more and more, which will have greatinfluence on the power grid, and creat new problems to power grid planning and design,scheduling operation and protective control etc., so it is necessary to do research on electricvehicles and its related plugged-in technology when they are of high penetration. In this paper,Firstly, the concept and state-of-the-art of V2G were reviewed based on the existing researchresults. Secondly, several models and scopes of application for electric vehicles connected to thegrid realized in China are discussed. Based on analysis of the models, a new model integratingelectric vehicles into the grid through multi-microgrids under the environment of smart grid inthe future in China is proposed. Next, a framework of vehicle-to-grid under this mode are studiedand designed preliminarily, related players involved in the framework are described in detailfrom two different domains, the grid technical operation and the economy of electricity markets. Then, a demand side management scheme for electric vehicles aggregation in the unitparticipating in frequency regulation service is introduced and designed in detail. For the scheme,a mathematical model of planning target is established. And then, two examples are presented toillustrate the scheme by choosing the peak and valley time price and spot price data. Finally, byusing MATLAB tool, combined with dynamic programming algorithm and the objectivefunction, simulation for the scheme on frequency regulation is made, and the correspondingsimulation results are given, the results show that the algorithm can well meet the optimizationdesign of the scheme demand.