Despite the widespread popularity of DC microgrid (DCMG), one of the key issues faced by it is the instability arising from supply-demand imbalance, which is conventionally tackled via energy storage units such as batteries. But the life cycle of the battery, which may reduce when subjected to transients, can be prolonged by integrating fast acting supercapacitor (SC) with higher power density. Such a combination of energy storage units enables the DCMG to handle steady state and transient conditions effectively. However, the reduction in the operating voltage of SC may bring in ringing in the DC bus voltage, which will affect DCMG stability. Hence, this paper focuses on analysing the impact of SC voltage deviation on DCMG stability and to propose a controller design procedure with conventional PI controller and power management strategy to mitigate the aforementioned consequences. The simulation in MATLAB and real-time validation in OP4510 real-time simulator has been conducted. The results of both revealed that the proposed scheme has succeeded in eliminating ringing of DC bus voltage, irrespective of the SC operating voltage variations, thereby maintaining DCMG stability.

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Incorporation of intermittent renewable sources and nonlinear loads to DC microgrid (DCMG) has increased its vulnerability to voltage instability and flicker. An innovative Demand Side Management (DSM) program that can help in mitigating these voltage disruptions is the deployment of DC Electric Spring (DCES) technology. In this regard, this paper focuses on small signal modeling and controller design of shunt DCES (ShDCES) in DCMG. The test system comprises of an MPPT controlled Solar Photo-Voltaic (SPV) system, battery-operated DCES and various loads. The MATLAB / Simulink performance analysis of the system indicates that, with the incorporation of power management strategy, the ShDCES configuration has enhanced the power quality of SPV-fed DCMG with fast dynamic response in comparison with its “series” counterpart. The effective utilization of battery operated DCES on the load side, instead of the source side, makes it less battery dependent, resulting in enhancement of battery life and lesser environmental hazards. The simulation results are also validated using real-time simulator OP4510 RTS.

Deployment of DC Electric Spring (DCES) technology is an innovative demand side management (DSM) program that helps to mitigate voltage interruptions. Conventional control strategy uses proportional-integral controllers to regulate DC spring parameters. As PI controllers have a trade-off between settling time and peak overshoot, they may not be able to achieve the desired dynamic performance under varying DC microgrid (DCMG) conditions. In this regard, this paper proposes an inverted zero compensator for the control of shunt DCES (ShDCES) in DCMG. This controller regulates the ShDCES current and terminal voltage under all operating conditions with reduced settling time and peak overshoot. A power management algorithm is also proposed to optimize the operation of ShDCES under the presence of varying PV generation and critical and noncritical loads. A detailed mathematical analysis of ShDCES and inverted zero compensator design are furthermore incorporated to validate the strategy. The simulation of the proposed method is performed in MATLAB/Simulink environment. The comparison analysis with the conventional controller proves the effectiveness of the new controller. The results are also validated using real-time simulator OP4510RTS.