Decentralised control of parallel inverters in an AC microgrid using downstream current as an implicit communication method

Traditional droop control in AC microgrids relies on telecommunication between a central controller and distributed generators for frequency and voltage restoration. This makes optimal operation of the microgrid vulnerable to a single point of failure i.e. the central controller. The aim of this paper is to propose a decentralised control strategy that supplies the microgrid load with its demanded current in agreed and equitable fashion, based on local information only and using no telecommunications. Fundamental to the proposed concept is a parallel arrangement between distributed generators and the local loads. In this arrangement the locally measured downstream current is used to derive the current reference for the primary-level control loop in each distributed generator. Use of the downstream current as an implicit communication method facilitates stable operation of the microgrid and elimination of undesired circulating currents. The paper validates the developed concept via detailed simulations under a range of realistic scenarios.