Hierarchical Optimization of Electric Vehicle System Charging Plan Based on the Scheduling Priority

摘要

Unregulated charging of a large number of electric vehicles (EVs) simultaneously may cause electricity shortages and price spikes in the power market. This paper deals with the optimization of EV charging strategy using the priority sequence. Firstly, the evaluation indices such as the schedulable interval ratio, the emergency probability and the battery losses are proposed. Then a comprehensive evaluation system for the EV scheduling priority is established by adopting the entropy weight method to incorporate multiple indices. Based on the scheduling priority obtained, a double-hierarchical optimal model is proposed, taking into account the constraints such as the demand of the EV owner. Its upper objective aims to minimize the sum of the square of deviation between the actual and the required schedulable capacity of EV aggregator over every interval. The lower one minimizes the sum of EV scheduling priority sequence over the scheduling interval. Case studies with 100 EVs show that the hierarchical optimization model can assist EV aggregator in making effective charging scheme. It is also observed that better flexibility for dispatching EVs can be achieved using multiple indices with weights.