An Analytic Method for Frequency Nadir Estimation in Fast Frequency Response Resource (FFRR) Dominant Power Systems

This paper proposes an analytic method foresti mating frequency nadir in power systems dominated by fast frequency response resources (FFRRs). The proposed method approximates the frequency response of FFRRs, which could be either complex or whose internal logic is not disclosed generally. This is because commercial-level models are typically provided as black box systems in large power system analysis. With the approximated transfer function, the frequency response following a major disturbance is represented by a simple equation that resembles the general solution for a second-order system's impulse response. The proposed method is validated through case studies of Jeju Island's power system in South Korea, employing user-defined models (UDMs) for high-voltage direct current (HVDC) systems. Results demonstrate that the proposed method predicts frequency nadir with high accuracy, which is almost identical with those of PSS/E.