Fast frequency oscillations detection in low inertia power systems with excessive demand-side response for frequency regulation

The reduction in inertia present in electric power systems due to the increase in renewable generation interfaced with power converters presents various challenges in power system operation. One of these challenges is keeping the frequency of the system within acceptable bounds, as the reduced inertia allows faster changes in frequency. A possible way to mitigate this effect is to introduce a certain degree of frequency response in the demand side, in such a way that a loss in generation leads to a decrease in the demanded power, levelling the generation-demand balance. In this paper, one limitation of this approach is analysed, specifically the case where the demand response is excessive to the system inertia and demand, producing fast frequency oscillations. A scenario where this happens, on a simulated islanded system based on the electric power system of the island of San Cristóbal, in Galápagos (Ecuador), is studied, and a method of detecting these oscillations is proposed, as a first step to develop an appropriate response to them.