In a practical islanded microgrid system, the mismatched line impedance causes serious problems such as inaccurate power sharing and circulating current. In order to overcome these issues, this paper proposes a coordinated virtual impedance control strategy for distributed generation units (DGs). In the proposed control strategy, both virtual resistance and virtual inductance are simultaneously tuned to compensate the mismatched line impedance among DGs, and the microgrid system stability is enhanced by increasing damping for the whole system. Also, the virtual impedance is adaptively regulated in order to guarantee a good power sharing performance even if the communication is interrupted or the load changes suddenly. The controller design process and theoretical analysis of the whole system are presented in detail based on small signal analysis. The feasibility and effectiveness of the proposed control strategy were validated by simulations and experiments with a 1.3-kVA prototype microgrid com-posed of three DGs.

Line impedance mismatch and unregulated harmonic currents cause serious problems for an islanded microgrid, such as inaccurate reactive power sharing and voltage distortion at the point of common coupling (PCC). To overcome these issues, a coordinated virtual resistance and capacitance are introduced together with its control scheme for parallel distributed generation (DG) in an islanded microgrid. The proposed coordinated virtual impedance control scheme directly modifies the DG output impedance at the fundamental frequency to realise accurate current sharing among DG units. In addition, a variable harmonic impedance control loop is proposed for each DG to absorb the non‐linear load harmonic current. Thanks to the proposed control scheme, the PCC harmonic voltage distortion is successfully compensated and power‐sharing among DG units is accurately achieved. The stability of the microgrid system was analysed in detail to verify the feasibility of the coordinated virtual impedance control scheme. Experiments on a laboratory prototype microgrid are performed to validate the performance of the proposed control scheme.

To ensure the stable and accurate operation of "rural areas”, a reliable power source is necessary, and voltage issues must be carefully considered in power system design to ensure patient safety. Remote DC microgrids provide a viable option for transferring energy across power sources while assuring stability and high efficiency. In this paper, an adaptive droop control approach is developed and compared to the standard droop control method. The suggested technique recommends a dynamic modification of droop coefficients intending to effectively limit the buildup of mistakes in current sharing and departures from the preset voltage setpoints. Through the implementation of the adaptive droop control method, the remote DC microgrid not only enhances current balancing performance but also contributes to a substantial improvement in voltage stability, thereby increasing the overall operational efficiency of the system. Simulation and experimental results on a small-scale remote DC microgrid validate the proposed adaptive droop control approach, proving its effectiveness in the small-scale microgrid system.