Power ramp-rate control based on power forecasting for PV grid-tied systems with minimum energy storage

Passing cloud results in rapid changes of irradiance. The intermittency of PV power output has drawn serious concern when the system is connected to electricity networks. The energy storage system (ESS) is considered as the most promising solution to balance and smooth the PV generation. Consequently, power ramp-rate control (PRRC) has been introduced to avoid significant PV power fluctuations. However, the high cost of ESS is still hindering its extensive application. Therefore, an effective ESS control strategy is demanding to comply with the regulations whilst minimize the ESS power and energy capacity. In this paper, an innovative ESS control strategy is presented, which utilizes the short-term forecasting. The solution activates the ESS system just before the actual cloud shading occurs. It requires only one-quarter of the energy capacity of the conventional ESS control strategy. The effectiveness of the proposed control strategy has been verified through simulation by using the real PV output power data of a 1 MW system.