An evaluation method of distributed generation credible capacity based on island partition

Abstract

Distributed generation (DG) has not only electricity value, but also capacity value. The capacity value can be represented by the credible capacity (CC) based on the equal power supply reliability criterion. The evaluation of reliability on distribution network (DN) is the core of CC calculation. Under a fault state, DGs can continue to supply power to some load by the island operating mode, and the DN reliability can be improved. Therefore, it is necessary to utilize the power supply restoration potential of DG and formulate an island partition scheme accurately in the reliability calculation of DN. A DG CC evaluation method based on island partition is proposed in the paper. The power supply reliability of an active distribution network is evaluated based on an island partition model, to realize the accurate evaluation of DG CC. The main work is as follows: First, an island partition model under a random fault state of DN is established. The fluctuation of DGs and load, interconnection switch, load priority, secondary outage constraint and other factors are fully considered in reliability assessment. A heuristic prospective greedy algorithm and the Prim algorithm are used to solve the island partition model accurately. Second, a reliability evaluation method of DN based on sequential Monte Carlo simulation (SMCS) is proposed. The system reliability level can be accurately analyzed under a fault state. Then, a CC evaluation method based on hypothesis testing is proposed. The convergence of the CC searching process can be scientifically judged by checking the conspicuousness of the reliability indices distribution obtained by the SMCS. Finally, a case study of the PG&E 69-bus system is analyzed. The topology of the DN, permeability of the DG and island partition strategy are known to have a significant impact on the DG CC.