The high penetration of photovoltaic (PV) generation has introduced critical control challenges for modern power systems, such as reduction of the system power reserve and degradation of the inertial response, frequency control, and voltage control. In response to these challenges, grid codes increasingly require PV power plants (PVPPs) to provide ancillary services through power reserve control (PRC) to mitigate the detrimental impact of PV generation and increase the reliability and dynamic performance of modern power systems. The development of practical approaches for PRC in PVPPs operating under dynamic irradiance conditions is challenging due to the fast variations in the maximum available power. To address this issue, this work presents a low-cost and straightforward PRC approach for PVPPs operating under cloud or clear-sky scenarios without incorporating additional devices in the power plant. A practical approach to estimate the maximum available power typically required to implement most PRC approaches is proposed based on multiple reference inverters (i.e., PV generation units, PVUs). An analytical expression is derived to determine the number of PVUs that must be operated in de-loaded control mode using a classical flexible power point tracking (FPPT) algorithm. A PVPP with 49 PVUs is employed to validate the overall formulated control approach using time-domain simulations, incorporating realistic technical and meteorological parameters alongside an accurate dynamic model. A comprehensive assessment is also conducted to investigate the impact of intrinsic and extrinsic factors on the performance of the PRC, showing the key challenges inherent to the PRC.
Menezes et al. (Thu,) studied this question.