Frequency Response Constrained Economic Dispatch with Consideration of Generation Contingency Size

Primary frequency response (PFR) requirements to stop frequency excursion after contingency are usually calculated on the basis of the potentially largest contingency, which is therefore a direct driver for frequency response adequacy. Future lower-inertia systems with larger volumes of non-synchronous renewables might require much higher levels of PFR to guarantee frequency adequacy; this might in turn significantly constrain system operation. Contingency size reduction could then potentially lead to a more efficient operation, and in extreme cases, it might be necessary to find feasible operation points. Hence, focusing on generation contingency, this paper presents a novel mixed integer linear dispatch model that includes a set of hyperplanes that describe PFR requirements as a function of both system inertia and maximum contingency size (as a variable of the problem) to comply with predefined frequency response constraints such as rate of change of frequency (ROCOF) and frequency nadir. This allows efficient control of the contingency size in order to reduce operational costs and renewable curtailment associated to the need for additional inertia and/or spinning headroom to guarantee adequate frequency response. The proposed approach is demonstrated through Australian case studies, also including specifically developed frequency response security maps.