A Distributed Feedforward Approach to Cooperative Control of AC Microgrids

This paper addresses the cooperative control problem of AC microgrids consisting of both voltage-controlled voltage-source inverters and current-controlled voltage-source inverters. The voltage-controlled voltage-source inverters dictate the frequency and voltage of the microgrid and the current-controlled voltage-source inverters provide quick and decoupled active and reactive power support to the microgrid. To handle the nonlinear and heterogeneous dynamics of the inverters, we have developed a distributed feedforward approach based on the cooperative control of multi-agent systems. The proposed controller presents three advantages in comparison with the existing works. First, all the inverters share one communication network, and the locations of the inverters over the communication network can be arbitrarily sited as long as all the inverters are connected. Second, the selection of the control gains does not rely on either the whole microgrid dynamics or the topology of the communication network. Third, the inverters' dynamics after input-output feedback linearization are allowed to be different. The effectiveness of the proposed controller is verified by the simulation study of a microgrid system for three cases, i.e., frequency and voltage restoration after islanding, active and reactive power adjustment after abrupt load changes and system performance subject to communication link failure and restoration.