Comparison between Decentralized and Centralized Energy Storage Systems for Power Ramp Rate Control of PV Systems

Abstract

The present pace of photovoltaic (PV) system installations is leading to a huge need for energy storage systems (ESS) to smooth fluctuating PV production. In this paper, a systematic comparison between decentralized and centralized ESSs for power ramp rate (RR) control of PV systems is presented based on inverter level power measurements of a large-scale PV plant. The result show that the relative ESS power capacity needed to smooth all PV power fluctuations decreases with increasing PV system size. The reason for this is that the required power capacity results from the fastest power fluctuations which smoothen with increasing PV system land area. This means that the ESS power requirements of large-scale PV plants can be minimized by using a single ESS for RR control of the entire PV plant instead of distributing the ESSs for single sections within the power plant for individual inverters. Differences in ESS energy requirements and amount of energy cycled through the ESSs between the decentralized and centralized ESS setups were found to be small.