A multi-level control architecture for master-slave organized microgrids with power electronic interfaces

Abstract

This paper presents a multi-level control architecture for autonomous operation of islanded microgrids with power electronic interfaces. An upper layer performs calculations for system dispatch while a lower layer computes appropriate control actions for the power electronic interfaces. The upper layer of communication-based intelligent control is realized through a decentralized multi-agent system (MAS). Two control strategies are implemented in this layer: MAS power balance control and economic dispatch. In MAS power balance control, a rational communication scheme is proposed to construct a minimal spanning tree structure among agents, so that the multi-agent system can efficiently discover system global information and dispatch generation and load to maintain real and reactive power balance; in economic dispatch, by comparing incremental cost with neighbors, generator agents can achieve minimum generation cost for system operation. To demonstrate the speed and effectiveness of the proposed algorithms, IEEE 14, 30, 57 and 118 bus systems are studied for the MAS power balance control and economic dispatch in MATLAB. A demonstration presents implementation of multi-agent system using Java agent development framework and includes a viable implementation of the lower layer, which is used to control power electronic interfaced distributed generators, and is realized through conventional local controllers for master-slave organized microgrids. A case study with time-varying loading conditions is demonstrated to validate the proposed multi-level control architecture.