Three-stage scheduling scheme for hybrid energy storage systems to track scheduled feed-in PV power

摘要

Tracking feed-in schedules (FISs) of photovoltaic (PV) systems using energy storage systems is a feasible method for making PV power as flexible as traditional power. Traditionally, the battery energy storage system (BESS) is used to track the FISs, but it can only confine the feed-in PV power in an error band rather than tracking the FISs precisely because of its limited capacity. To improve FIS tracking precision, a three-stage scheduling scheme is proposed, which employs the hybrid energy storage system (HESS) composed of batteries and electrolyzers. In the first stage, i.e., day-ahead scheduling, the FIS is designed by dividing 24-h-ahead forecast PV power into two parts, where the stable part is supplied to the power grid and the fluctuating part is absorbed by the HESS. In the second stage, i.e., 15-min-ahead scheduling, the FIS is cyclically modified according to 15-min-ahead forecast PV power to prevent the HESS from overload. In the third stage, i.e., real-time scheduling, the actual feed-in PV power and the real-time input power of the HESS are calculated based on the real-time PV output power and the state of charge of the HESS. Furthermore, this scheme is compared with another scheme that tracks the FISs with BESS, and its superiority is demonstrated from both technical and economic perspectives.