A Hierarchical Dispatching Model Considering Temporal And Spatial Optimal Distribution Of Electric Vehicles

With increasing concern over energy and environmental crisis, government paidmuch attention on energy conservation. Promoting electric vehicles(EVs) is one of thebest ways. As the dual characteristics of battery energy storage, EVs can be used as load,as well as power sources during peak load through Vehicle-to-Grid technology. With thebreakthrough of battery technology, EVs will eventually become an important part ofthe smart grid as a distributed energy storage devices.First of all, this thesis analysis the impact of large-scale EVs on distributionnetworks and scheduling management. Then a hierarchical economic dispatch modelhas been proposed against the decomposition and coordination problems, temporal andspatial distribution and charging/discharging randomness of EVs scheduling. It can bedivided into two layers, which are the bi-level economic dispatch model consideringspatial-temporal distribution of EVs and optimal charging and discharging schedulemodel. The purpose of the paper is to reduce the negative impact of large-scale EVs onthe grid and lay the theoretical foundation for EVs interacting with the power grid.Furthermore, based on traditional security constrained unit commitment, this thesisproposed a bi-level economic dispatch model considering spatial-temporal distributionof EVs. This model was separated into two sub-models. Internal model is the unitcommitment model considering electric vehicle aggregator based on optimal power flow.According to the forecasted load next day and the aggregator dispatching scheduleobtained by external model, the internal model can output the optimal each generationpower to minimize the total cost. The external model is the optimal aggregator charging/discharging scheduling model. Based on the interactive information of EVs within anaggregator’s jurisdiction, aggregator power scheduling is obtained to minimizedistribution network loss. Simulation results with a six-bus system and an IEEE-30system show that this model can realize aggregators interaction with grid, reducing theoverall cost and minimizing network loss. The results has certain significance to thecharging and discharging node selection.Finally, considering the convenience of EV owners, the optimal charging anddischarging schedule model based on scheduling priority is presented. By analyzing theimpact of EVs declared information on strategies of the aggregator’s planning, theevaluation index system is established. It is consist of EVs declared capacity and time, battery consumption and integrity. EVs charging and discharging scheduling is obtainedto satisfy the plan made by dispatch organization through the scheduling priority, whichcan be calculated by entropy-weight method. Then the feasibility and correctness wasverified through a4-bus an two aggregators system. Results show that the method canreflect the impact of each index of EVs on scheduling strategy, and can effectivelyrealize the scheduling plan for electric vehicle aggregator.