Two-stage flexibility improvement optimization method of distribution network considering EV charging and scheduling of energy storage and interruptible loads

The frequent fluctuation of distributed generation output and the disordered charging of EVs(Electric Vehicles) make the insufficient flexibility of distribution network become more and more prominent. Therefore, it is necessary to improve the flexibility and adaptability of distribution network by scheduling the flexible resources effectively. On the basis of fully analyzing the flexibility improvement measures of distribution network, three flexibility evaluation indexes of net load peak margin, net load valley margin and net load allowable fluctuation margin are presented. A two-stage flexibility improvement optimization model of distribution network is established, which considers the EV charging and the scheduling of energy sto-rage and interruptible loads comprehensively. In the first stage, the ordered charging strategy of EV based on Monte Carlo tree search is constructed to reasonably guide the EV loads to charge in the valley period. Based on the first stage, an optimal scheduling model considering energy storage and interruptible loads is established in the second stage, which is solved by using particle swarm optimization algorithm. The example of IEEE 33-bus system verifies the effectiveness of the proposed flexibility indexes and the EV ordered charging model, and the results show that the two-stage flexibility improvement optimization method can effec-tively improve the flexibility of distribution network and the overall economy is optimal. © 2020, Electric Power Automation Equipment Press. All right reserved.