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Management of battery at direct current (DC) microgrids is the essential factor to maintain the balance of power and the bus voltage's stability in the grids. To ensure the quality of battery management is necessary to simulate the operation of the battery management system. This paper presents the simulations in various battery management algorithms. The simulations were designed to determine the effect of these variations on the balance of the power balance, bus voltage stability, and battery consumption level. The configurations of one, two, and three battery groups could maintain a balance of power balance. The three arrangements could ensure the bus voltage stability at a value of 24 Volts. The variations in the battery group configurations cause different battery consumption levels. The three-battery group configuration has a lower power consumption rate of 0.1% than other battery group configurations. Variations in the battery management algorithms affect power balance, bus voltage stability, and battery electricity consumption. The result showed the best power balance achieved by an algorithm without counting a value-based state of charge (SoC). The algorithm also committed that the difference between the supply and demand equal to 0 Watts. For the voltage stability, the algorithms that were counting a value-based SoC can maintain bus voltage stability at a value of 24 Volts. Nevertheless, other algorithms that rely on less than one SoC value-based and have the lowest mean value of SoC reduction are equal to 0.19%.

The direct current (DC) microgrid requires a fast load shedding scheme that prevents instability and voltage collapse when the distributed energy resources are unable to meet the power demand. The load shedding scheme is also expected to prevent unnecessary service interruptions caused by over-shedding of loads. This paper proposes an adaptive voltage-based load shedding scheme utilizing voltage thresholds that are automatically adjusted depending on the rate of change of locally measured bus voltages. The performance of the proposed load shedding scheme is investigated and compared with that of the conventional voltage-based load shedding scheme, using a realistic and detailed study system, under various disturbances. The comprehensive simulation studies that are conducted using the PSCAD software indicate that the adaptive load shedding scheme (i) effectively maintains the DC microgrid power balance through fast and coordinated load shedding, (ii) prevents the DC bus voltages from falling below acceptable levels, (iii) ensures that the critical loads do not experience excessive steady-state voltage deviations, (iv) minimizes the durations and magnitudes of the temporary voltage drop caused by sudden disturbances, and (v) improves power supply reliability.

This study proposes a versatile decentralised control strategy for the direct current (DC) microgrid based on the DC bus signalling method. Performance of the proposed control strategy is investigated under various generation and load disturbances in both grid-connected and islanded operation modes of the DC microgrid. The studies are conducted using a realistic DC microgrid study system simulated in the PSCAD/EMTDC software. The study results indicate that the proposed control strategy: (i) effectively maintains the power balance in the DC microgrid, (ii) effectively limits the DC bus voltage deviations under large disturbances, (iii) improves stability and dynamic response, (iv) does not curtail renewable power generation unless it is necessary, (v) does not require excessively large grid-tied converter and battery energy storage systems, and (vi) enhances system reliability, flexibility, modularity, and expandability.

A direct current (DC) microgrid has become a superior power system in recent years due to the development of DC loads and higher efficiency of DC systems. One of the challenging problems on DC microgrids operation is protection, and it is still a particular concern associated with the challenges of developing a proper protection scheme owing to its characteristics and lack of standards in DC protection. Due to the significant increasing interest on DC microgrid; this study investigates protection problems and schemes that need to be addressed in modern power systems involving DC microgrids. This study analyses and presents a comprehensive review of the most recent growth in the DC microgrids protection. Additionally, the fault characteristics of DC microgrids, the impact of constant power loads, the protection devices and several proposed methods to overcome the protection problems are discussed. The differences between the proposed protection methods for the DC microgrids are also discussed.