Abstract

Background: Microgrid is an effective integration mode of distributed generation (DG). It can eliminate the negative effect caused by the intermittent DG and consume the energy locally.

Methods: For a public distribution network, a microgrid performs as a controllable and flexible unit. However, when the public distribution network has the demand of flexible regulation, there is no reasonable quantitative indexes to evaluate the flexibility of microgrid for dispatching decision. For this problem, the operational flexibility indexes of a microgrid are defined in this paper.

Results: The indexes are quantified according to the maximum energy and active power regulation margin of each flexible equipment in the microgrid. The operational flexibility of microgrid is closely related to the scheduling strategy. Therefore, the corresponding dispatching model of a microgrid is also provided in this paper.

Conclusion: A case study shows how to calculate and use these flexibility indexes in an operation cycle of a microgrid system with energy storage (ES) facility and demonstrates the availability and practicability of the evaluation indexes and the method.

Keywords: Microgird system, energy storage, operational flexibility, evaluation index, economic dispatch, generation control.

Graphical Abstract