The negative solar resistance, is highly dependent on the solar operating point. The system will become sluggish and unstable during low irradiance. It is reported that the impact of negative solar resistance is nullified by parallel impedance emulated condition (PIEC). During low irradiance, the system stability has been moved to an unstable position which is not fully resolved by PIEC. In this paper, a virtual inertia-damping voltage and current solar droop emulated controller is proposed to improve the voltage oscillation profile, inertia problem and damping of the DC microgrid system. In DC microgrids, the inherent inertia from DC capacitors is low, thus affecting the bus voltage oscillation during a reduction of irradiance. The oscillation of the system has been increased due to the equivalent impedance by negative solar resistance at lower irradiance. Oscillation’s issue and voltage instability of the PV system have been enhanced by the inner current controller. In addition, the steady-state error of the PV voltage is minimized by the virtual inertia-damping voltage restoration droop controller with PIEC. Performance analysis and dynamic characteristics are discussed through a pole-zero plot for the various conditions of negative solar resistance using virtual inertia-damping voltage and current Solar Droop Emulated Controller. This paper focuses on stability analysis to strengthen the DC microgrid. The performance of the solar controller with bidirectional converter (BDC) controller has been discussed to verify the power management between the system to manage the power for the unbalanced load.

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Summary This article mainly focuses on the analysis and design of a dynamic hybrid optimized controllers for unbalanced DC microgrid. Small‐signal model analysis of unidirectional boost converter (UBC) and bidirectional converter (BDC) is discussed to get the efficient performance not discussed earlier. The hybrid controller manages the power between BDC and solar with UBC during the unequal loading. The problem associated with nonlinear solar I‐V curve effect is expressed by dynamic resistance. It is affected by parametric variation as the operation point of I‐V curve, temperature, and solar irradiance. The slower transient response of PI voltage and the current controller is not an effective solution for parametric variations. To address this, a simple hybrid genetic algorithms (GA) based closed current and voltage‐controlled loop is designed using proportional‐integral (PI) controller. Small‐signal model with consideration of dynamic resistance in solar model with UBC connected to BDC fed DC microgrid is described for nonlinear structure. The closed‐loop stability of GA‐based voltage and the current PI controller are verified under the deviation of load parameters using a bode plot. It covers the overshoot, time response, oscillation, and dynamic stability under the parametric variations. GA PI controller has fast response comparison to Ziegler Nichol's method as settling time, peak overshoot, rise time, and more stable. The comparison of these two methods is described under fixed and variable loading for microgrid by MATLAB/Simulink. Detailed case study for dynamic operation is verified for unequal loading between the system and dc load.

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