Centralized multi-microgrid control: peer-to-peer power trading for battery life extension and enhanced outage/fault resilience under generation uncertainty and demand variations

• An MMG with two MGs for on-grid and off-grid operation modes is designed. • A single MMGCC unit for enhanced MG communication and coordination is developed. • P2P power exchange while minimizing battery cycles in MGs is implemented. • Control strategies for independent MG operation during outages is established. • Robust P2P exchange between MGs under off-grid critical conditions is enabled. This article presents several strategies for managing multi-level peer-to-peer power trading between the microgrids (MGs) within a multi-microgrid (MMG) system and the utility grid. These strategies apply to cases when the MGs are in on-grid mode, operating off-grid, and engaging in mutual power trading among interconnected MGs. The MMG under consideration includes two MGs, each equipped with either a wind turbine or a photovoltaic system, along with a battery unit to support variable three-phase loads. In each MG, there is a microgrid central controller (MGCC), which is responsible for communicating, exchanging information, and issuing necessary commands to the local controllers (LCs) under its command. A multi-microgrid central controller (MMGCC) is also responsible for monitoring and supervising the MGCCs. In on-grid mode, each MG uses control schemes to manage power exchange with the main grid. These strategies aim to minimize battery charging and discharging cycles when selling excess power to the grid, while also considering factors such as the uncertainty of distributed generation (DG) outputs and fluctuations in load demand. In off-grid mode, MGs are designed to operate independently under normal conditions, with specific control strategies implemented for islanding scenarios. Furthermore, MGs can provide mutual support during critical outages and fault situations and work in an interconnected mode. Nonlinear simulations conducted using MATLAB/Simulink demonstrate that the proposed control methods effectively achieve all objectives. These purposes include adequately supplying MG loads, accounting for uncertainty in power generation and demand variations, managing power exchanges between MGs and the utility grid while reducing the frequency of battery charging and discharging cycles in on-grid mode, ensuring optimal performance of each MG in off-grid conditions, and enabling robust performance of off-grid MGs through peer-to-peer communication between MGs in interconnected conditions.