With the high penetration of distributed generators (DGs), it puts higher requirements on the operational flexibility of active distribution networks (ADNs). Operational flexibilities are from controllable resources (CRs) within the feeders. However, due to the secure operational constraints of distribution network, the flexibilities of CRs cannot be fully translated into feeder operational flexibilities. In this paper, to quantify the feeder operational flexibility for flexible, efficient and secure operation of ADNs, a quantification analysis method is proposed. The definition and mathematical expression of feeder operational flexibility are proposed firstly. By constructing a multi-dimensional state space, state equations of operational constraints are presented. Then an analytical framework for quantifying the feeder operational flexibility in ADNs is proposed. Finally, based on Monte Carlo simulation, case studies are performed on the modified IEEE 33-node system.
Keywords feeder operational flexibility; active distribution network; controllable resources; Monte Carlo simulation