An Improved Method to Estimate Maximum Available Power for Frequency Support From Solar PV Plants Under Varying Weather Conditions

The accurate estimation of the maximum available power (MAP) in a photovoltaic power plant (PVPP) is critical for assessing its capability to sustain an operating reserve required for participation in frequency support services. The challenge lies in maintaining a continuous generation margin due to the inherent intermittency and variability of solar irradiance, driven by varying and uncertain weather conditions. In this regard, a straightforward method for estimating real-time MAP in PVPPs has been proposed involving the periodic and synchronized maximum power point tracking (MPPT) operation to precisely estimate the instantaneous MAP and assist in frequency regulation. The proposed approach requires the synchronized operation of the inverters in MPPT and active power control (APC) modes during changing irradiance conditions, in addition to a supercapacitor-based energy-storage system (ESS), to offset the increase in power during MPPT operation. The presented method has been validated on test PVPP models utilizing simulated and measured irradiance datasets. Its estimation accuracy has been evaluated through comparison with a benchmark approach from the literature using appropriate performance metrics. The results demonstrate that the proposed strategy can deliver adequate flexibility in PVPP operation, offering on-demand secondary frequency support with less implementation complexity and exhibiting optimistic economic benefits despite the uncertainty associated with solar radiation.