Credible capacity calculation method of distributed generation based on equal power supply reliability criterion

Abstract

Increasing distributed generation (DG) enables distribution network (DN) carry more load. Therefore, DG includes both electricity and capacity values. The DG capacity value can be regarded as increased load capacity under equal power supply reliability, typically referred to as credible capacity (CC). A CC calculation method of DG based on equal power supply reliability criterion is proposed in the paper. The unserved electricity under fault state and insufficient electricity under normal state are both considered in reliability estimation for the first time. Firstly, an island partition optimization model is established to evaluate the unserved electricity under fault state. A heuristic prospective greedy algorithm is utilized to formulate the island schemes dynamically. Then, a minimizing load curtailment model is established to evaluate the insufficient power supply under normal state. DN steady-state security region method is introduced to avoid repeated power flow calculation. Finally, the DG CC calculation is conducted for the IEEE 33-bus system by the proposed method. It is found that the CC value will have a big deviation if the insufficient electricity under normal state is ignored. When the DG permeability increases from 10% to 50%, the CC value is about 30%–20% of the total capacity.