Adaptive Ramp-Rate Control of Hybrid Energy Storage System for PV Application

With the increasing penetration of solar energy, a huge amount of fluctuating power is injected into the power grid, which has a negative influence on power quality (e.g., voltage fluctuation). To solve this problem, power ramp rate control has been introduced in grid codes. In recent years, hybrid energy storage systems have been widely used in many applications for limiting the ramp rate of the power, due to their control flexibility. Currently, the integration of supercapacitors in such hybrid systems is a promising solution to extend the battery lifespan and improve dynamic performance. In this paper, an adaptive ramp-rate control strategy is conducted by using low-pass filters, which can change the filter time constant to reduce the battery cycles. The results show that compared to the traditional two-stage strategy, the proposed strategy can effectively reduce the battery cycles by nearly 18% during days of fast-moving clouds.