A Voltage-Zone Based Power Management Scheme With Seamless Power Transfer Between PV-Battery for OFF-Grid Stand-Alone System

There is a requirement for a simple solution that provides seamless power management control and eliminates the issue of toggling between different operating modes in the stand-alone photovoltaic (PV) battery based hybrid system. The solution for the same is given in this article that uses a simple voltage control strategy. The given solution uses a voltage band technique for eliminating the toggling between charging and discharging modes. Further, the toggling between intermediate PV mode with charging and discharging mode is eliminated using the inner voltage band. Thus, the proposed control strategy provides a smooth and seamless control between different modes based on load voltage information. It avoids the overlap of charging and discharging modes within the switching cycle to improve the life-span of the battery. Also, the given control strategy does not require the power information and complex computations like division, etc., for its operation. The given solution can be easily implemented on any PV-battery-based hybrid system having independent control for charging and discharging of the battery with maximum power point tracking (MPPT). A simulation was done to verify the operation in various modes using seamless control. The simulation results are further justified with experimental results from the developed lab prototype.