Chapter 4 - Distributed power control of flexible loads in microgrids

Abstract

Flexible loads are distributed widely in civil or commercial areas, which have already accounted for a large proportion of the total electricity consumption around the world. This chapter studies the distributed power allocation control and distributed load following control of flexible loads in smart grids. In the first part, a novel distributed optimal dispatch algorithm is proposed for coordinating the operation of multiple micro units in a microgrid, which has incorporated the distributed consensus algorithm in multiagent systems and the λ-iteration optimization algorithm in economic dispatch of power systems. Specifically, the proposed algorithm considers the global active power constraint by adding a virtual pinner and it can deal with the optimization problem with any initial states. That is, it can realize the global optimization and avoid the defect of the initial conditions’ sensitivity in the optimization problem. In the second part, a demand response load following strategy is proposed for an interconnected source and load microgrid system, in which the traditional units and population of cooling thermostatically controlled loads (TCLs) are utilized to follow the mismatched power caused by the load activities and the renewable power injection in real time. In the demand side, these TCLs are often affiliated to a bus load agent and can be aggregated to multiple TCL aggregators. By proposing a distributed pinning control strategy and designing a spare communication network among the aggregators, the reference power tracking of the load agent can be shared by all aggregators inside it in a distributed way.