Distributed robust hierarchical power sharing control of grid-connected spatially concentrated AC microgrid

Abstract

This paper considers the power sharing problem for a grid-connected ac microgrid containing a cluster of spatially concentrated dispatchable distributed generators (DDGs), which are supposed to share the desired power demand according to some prespecified power sharing base. The power sharing problem is formulated as a tracking problem for an interconnected leader-follower multiagent system, which is solved by a novel distributed robust hierarchical control scheme. The proposed control scheme consists of two control levels, i.e., the secondary control and the primary control. The secondary control operates in a slow time scale, where each DDG exchanges information with its neighbors over the communication network to reach a global synchronous signal, according to which the local reference power output for each DDG is determined in proportion to its power sharing base. The primary control operates in a fast time scale, where local robust controller is designed to achieve local reference power output tracking in the presence of uncertain system parameters. It is proven that power sharing for all the DDGs can be achieved autonomously under the proposed control scheme, which is evaluated by comprehensive case studies.