Networked Microgrids for Self-Healing Power Systems

This paper proposes a transformative architecture for the normal operation and self-healing of networked microgrids (MGs). MGs can support and interchange electricity with each other in the proposed infrastructure. The networked MGs are connected by a physical common bus and a designed two-layer cyber communication network. The lower layer is within each MG where the energy management system (EMS) schedules the MG operation; the upper layer links a number of EMSs for global optimization and communication. In the normal operation mode, the objective is to schedule dispatchable distributed generators (DGs), energy storage systems (ESs), and controllable loads to minimize the operation costs and maximize the supply adequacy of each MG. When a generation deficiency or fault happens in an MG, the model switches to the self-healing mode and the local generation capacities of other MGs can be used to support the on-emergency portion of the system. A consensus algorithm is used to distribute portions of the desired power support to each individual MG in a decentralized way. The allocated portion corresponds to each MG's local power exchange target, which is used by its EMS to perform the optimal schedule. The resultant aggregated power output of networked MGs will be used to provide the requested power support. Test cases demonstrate the effectiveness of the proposed methodology.

I. Introduction

Microgrid is a power distribution system integrating distributed generators (DGs), energy storage systems (ESs) and controllable loads [1], [2]. An MG can work in a grid-connected mode or an islanded mode. A smart MG is distinguished from the traditional distribution systems in terms of reliability, self-adequacy, self-healing, and interactive characteristics [3]. According to recent studies in [2]–[9], connecting multiple MGs to form a power system can further improve the system operation and reliability thanks to the salient features of networked MGs such as coordinated energy management and interactive support and exchange.