Meeting frequency response requirements with uncertain system inertia — A UK perspective

National Grid has a statutory obligation to manage the frequency between pre-defined limits. If there isn't effective frequency response available then the likelihood of a frequency excursion outside of statutory limits will increase. To this end, National Grid are going to trial enhanced frequency response as a mechanism to assist with frequency control in the light of reducing system inertia. This paper models rapid response as a function of system inertia and proposes that either primary response needs to ramp up more quickly in order to remain effective at low system inertia levels or a faster response time is needed. It has been determined that both these methods are more effective than just increasing the generation held in reserve for frequency response. The outcome of this research supports the growing body of evidence in literature for the procurement of rapid response subject to further research and testing on the UK grid.