Microgrids (MGs) in which power generation and consumption occur locally have gained prominence, and MG demonstration tests have been widely carried out. In accordance with the increase in the number of MG installations, studies regarding the cooperative control of multiple MGs are proceeding in various forms. In this paper, the distributed control strategy of a multi-microgrid (MMG) is proposed. Distributed control is the method in which agents of the electric power facility autonomously control their facility through communication with the neighboring agents only. In this process, a consensus algorithm is utilized to obtain the global information required to control the overall system. In this distributed control strategy, a single MG is operated at an optimal economic point using the equality incremental cost constraints while maintaining the balance between the generation and demand. The control strategy of a MMG is that the flow of the point of common coupling (PCC) is maintained at a particular value needed by the utility and the internal change in power is distributed to the MGs according to their reserves. The proposed algorithm is verified in the MG level and the MMG level through a simulation model using PSCAD/EMTDC software in the C language.

Deviation of power frequency can greatly impact power system reliability, power quality and economic efficiency. This paper proposes the frequency control of energy storage system based on hierarchical cluster structure. A central agent named by power management system (PMS) contracts with utility for providing the frequency regulation. The agent also manages the whole cluster structure and balances the energy of each storage device. Several local sub-agents named by the energy storage system controllers (ESSC) intermediate between the power management system and the subordinate energy storage devices. The sub-agents perform the frequency response control by P-f droop, and set the power reference to the each energy storage device. Through the demonstration test, response time and ramp rate of the proposed structure and algorithms are calculated and performance of this system is confirmed.