Remote microgrids with battery energy storage systems (BESSs), diesel generators, and renewable energy sources (RESs) have recently received significant attention because of their improved power quality and remarkable capability of continuous power supply to loads. In this paper, a new proportional control method is proposed using frequency-bus-signaling to achieve real-time power balance continuously under an abnormal condition of short-term power shortage in a remote microgrid. Specifically, in the proposed method, the frequency generated by the grid-forming BESS is used as a global signal and, based on the signal, a diesel generator is then controlled indirectly. The frequency is controlled to be proportional to the AC voltage deviation of the grid-forming BESS to detect sudden power shortages and share active power with other generators. Unlike a conventional constant-voltage constant-frequency (CVCF) control method, the proposed method can be widely applied to optimise the use of distributed energy resources (DERs), while maintaining microgrid voltages within an allowable range, particularly when active power balance cannot be achieved only using CVCF control. For case studies, a comprehensive model of an isolated microgrid is developed using real data. Simulation results are obtained using MATLAB/Simulink to verify the effectiveness of the proposed method in improving primary active power control in the microgrid.

Recently, isolated microgrids have been operated using renewable energy sources (RESs), diesel generators, and battery energy storage systems (BESSs) for an economical and reliable power supply to loads. The concept of the complementary control, in which power imbalances are managed by diesel generators in the long time scale and BESSs in the short time scale, is widely adopted in isolated microgrids for efficient and stable operation. This paper proposes a new complementary control strategy for regulating the frequency and state of charge (SOC) when the system has multiple diesel generators and BESSs. In contrast to conventional complementary control, the proposed control strategy enables the parallel operation of diesel generators and BESSs, as well as SOC management. Furthermore, diesel generators regulate the equivalent SOC of BESSs with hierarchical control. Additionally, BESSs regulate the frequency of the system with hierarchical control and manage their individual SOCs. We conducted a case study by using Simulink/MATLAB to verify the effectiveness of the proposed control strategy in comparison with conventional complementary control.

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