Generic Low-Order Primary Frequency Response Model for Frequency Nadir Prediction

The frequency nadir (FN) is a crucial indicator for frequency stability. Accurate FN estimation helps operators assess stability risks and determine the required Primary Frequency Response (PFR) reserves. Existing analytical methods for FN estimation face problems such as poor applicability, inability to be numerically solved for FN, and a lack of analysis of the governor-turbine model needed to establish a low-order PFR model. This paper employs adaptable low-order fitting approaches to the governor-turbine model to propose a generic low-order PFR model. This model is applicable to various governor-turbine systems and scenarios where converter-based systems participate in PFR. Its low-order characteristic enables efficient numerical calculation of FN and quantitative tuning of control parameters for converter-based systems. To demonstrate the accuracy and applicability of the proposed method, case studies for FN prediction are carried out on the IEEE 9/39 bus systems, and parameter tuning for the High Voltage Direct Current (HVDC) system is presented when the HVDC provides frequency support to the AC system.