Comparing Different Regulation Offerings From a Battery in a Wind R&D Park

Abstract

Regulation is required to ensure that energy generation and demand on an electricity grid match at all times. Energy storage has been proposed to provide fast, precise regulation as wind energy and other renewable energies displace traditional generators that also provide regulation. In this investigation, different levels of regulation are offered using a 1 MW/2 MWh battery to determine the optimal offering for the system. The sodium–nickel chloride (Na-NiCl2) battery is charge rate limited, which affects the accuracy, especially at high states of charge. Offering a lower regulation capability increases the accuracy in the same state of charge range, but results in lower payments. Performing regulation behind the meter of a wind farm causes additional challenges due to the current electricity rate structure, which has a high demand charge during low wind generation periods. This causes the storage system to be limited to wind generation periods, resulting in regulation not being offered every hour. The battery achieved PJM performance scores above 90% while performing regulation, with month-long averages ranging from 59% to 63%, depending on the regulation offered. The maximum monthly revenue under the described operation, using PJM's regulation rates, is under 50% of the monthly cost of the Wind Energy Institute of Canada's USD 2.34 million dollar battery energy storage system.