A Robust Control Strategy for Power Management of an Islanded DC Microgrid

This paper deals with robust control strategy used for the power management of a DC microgrid. The DC mi-crogrid considered here comprises of a PV source, permanent magnet synchronous generator based wind system, hybrid storage combination of battery and supercapacitor and a DC load. The PV and wind systems are operating at maximum power point during normal operation. PV is operating in MPPT using P & O algorithm and wind is operating using optimum torque based algorithm. A control strategy has been proposed for power sharing between storage systems and renewable sources. This strategy uses the Lyapunov function and ensures global asymptotic stability of the closed loop system. The bypassing of high frequency components to supercapacitor in the control strategy helps in reducing the current stress occurring in the battery. A robust controller based on sliding mode is used for tracking the current reference in the wind energy system. A power management algorithm has been developed based on this control technique for balancing the power, when there is a change in the renewable input, SoC of storage systems or load. During these disturbances, the DC link voltage is tightly regulated. The effectiveness of this strategy is explored by formal analysis and simulation using MATLAB/Simulink.