A fast power reaching law-based robust integral sliding mode controller design for maintaining power-sharing in DC microgrids

A nonlinear robust integral-sliding mode controller for maintaining power balance in DC microgrids using a fast power reaching law is proposed in this paper. It is well-known that a steady DC-bus voltage is a key indicator to enhance the power-sharing in a DC microgrid. Hence, for maintaining a constant DC-bus voltage, it is essential to control the output voltage of different components of DC microgrids. To meet this control requirement, each microgrid component is interfaced to the DC-bus with a respective power electronic converter. In this paper, the proposed DC microgrid compromises with a solar photovoltaic (SPV) system, a battery, and DC loads. Hence, the SPV is interfaced with a DC-DC boost converter to match its output voltage with the DC-bus voltage. On the other hand, a DC-DC buck-boost converter is used with the battery to control its charging and discharging current. The controller is designed for all these components i.e., SPV and battery to control their corresponding output power while maintaining the DC-bus voltage at a constant value. Afterward, to prove the overall stability of the system with the designed control input, the Lyapunov theory is used. Finally, to validate the usefulness of the designed controller, a simulation study is conducted under different operating conditions and it compares with the existing controller to confirm its superiority.