A Sensitivity Analysis on Power to Energy Ratios for Energy Storage Systems providing both Dynamic Firm and Dynamic Containment Frequency Response Services in the UK

This paper presents a sensitivity analysis on the power to energy ratio for Energy Storage Systems (ESS) providing frequency response services on the Great Britain electricity network. Two services are considered; dynamic frequency response and dynamic containment, with the latter being a new service introduced in Oct 2020 by the Electricity System Operator. Each service proportionally responds in power to changes in grid frequency with each service differing in the response envelope. Whilst these services are based on power, for energy-limited assets such as ESS, the ratio of power to energy has an effect on its ability to deliver the service 100% of the time. In this paper, the availability, compliance against service terms and conditions, and equivalent cycles are considered showing that there is a significant difference between the two services. Currently, these services are delivered by battery ESS, however, it is demonstrated that the newer dynamic containment service can be effectively delivered by a higher power to energy ratio ESS and therefore offers opportunities for other technologies such as supercapacitors and flywheels.