On the relation between battery size and PV power ramp rate limitation

PV power fluctuations caused by clouds are leading operators of grids with high renewable energy penetration rates to impose ramp rate limitations. Costly battery energy storage systems are used for fulfilling these regulations but the question of the power and energy requirements for accomplishing them has not been fully answered. This work analyses the effects of reducing the size of a battery designed to absorb every fluctuation by taking into consideration, both, the fluctuation occurrence and the penalties in case of non-compliance of a given prescribed ramp-rate limitation. A theoretical analysis was carried out in order to assess the relation between size reduction and ramp rate compliance, obtaining as result a model for predicting the probability of non-compliances with a reduced battery. Additionally, the battery size reduction analysis was applied to the particular grid code currently proposed for Puerto Rico, creating new tools for selecting a battery with reduced power and energy capacity.