Tertiary Controller-Based Optimal Voltage and Frequency Management Technique for Multi-Microgrid Systems of Large Remote Towns

A voltage-frequency management technique is proposed in this paper to retain these quantities within acceptable limits in remote islanded microgrids (MGs). The proposed technique gets activated when existing techniques that control the energy storages or adjust the set-points of generators are not successful. This technique aims to provide external support to an overloaded MG or the one with excessive renewable generation by coupling it to one or more suitable neighboring islanded MGs at the lowest cost. The selected neighboring MGs should have enough unused generation capacity or available loading capacity to support the overloaded or over-generating ones. The technique finds an optimal mixture of demand response (load decrease or increase), energy storage charging and discharging, and renewable curtailment as the other auxiliary options. It is based on a modified version of particle swarm optimization with a suitable convergence for near real-time applications. An objective function which considers different technical, operational, and environmental aspects is formulated, and the required constraints are highlighted. Several simulation studies are also presented to validate its performance.