A cost-effective power ramp rate control strategy based on flexible power point tracking for photovoltaic system

•A flexible power point tracking (FPPT) strategy is proposed without additional hardware cost.•The algorithm is simple and effective for both ramp-up and ramp-down rate control.•A ramp-rate measurement (RRM) method is proposed to detect the power ramp-rate event.•The proposed PRRC strategy can regulate the ramp rate under 3W/s, which is effective with low cost. Due to the intermittent nature of renewable power generation, the power ramp-rate control (PRRC) strategy becomes essential for Photovoltaic (PV) systems with the increased penetration ratio recently. However, most of the PRRC strategies are based on energy storage systems, which require high installation cost. Therefore, it is important to find alternative technology to avoid the additional hardware components and make the PV system more cost-effective. In this paper, a novel PRRC strategy is proposed, which is based on a flexible power point tracking (FPPT) strategy without the additional hardware cost. Besides, a ramp-rate measurement (RRM) method is proposed to detect the power ramp-rate event. The proposed PRRC algorithm is suitable for both of the ramp-up and ramp-down cases. Furthermore, it is simple and effective in regulating the PV power fluctuations under the framework of grid code. The effectiveness of the proposed PRRC strategy is validated through simulation and experimental evaluation under various scenarios. The experimental results based on the real-filed meteorological profile validate that the proposed PRRC strategy can effectively regulate the ramp rate under 3 W/s, which is corresponded to 5% of the rated PV power/min.