Containing Loss Risk in a Low Inertia GB Power System

There is a reduction in the percentage penetration of synchronous machines within the GB power system; leading to a decrease in inertia, and an increase in system rate of change of frequency (RoCoF) following a frequency event. This raises the challenge of containing frequency deviations within the relevant operational limits. As a result, steps need to be taken by the system operator to manage the risk to system security. In order to better understand this risk, this paper presents the challenge in light of the changing energy landscape and the current and future frequency response services available to contain frequency deviations. Although frequency response services may be capable of containing some events within frequency limits, in low inertia scenarios these responses alone are not capable of containing excursions within practical RoCoF limits. Consequently, further action must be taken to ensure system security. The system operator currently employs an interim solution of limiting the largest loss risk, depending on system inertia and the RoCoF limit. While this is suitable in the short-term, it is unlikely that this option will be viable in the future.