Grid-Forming Converters Integrated Power System Frequency Response Model: A Parameter Estimation Approach

Abstract

This paper deals with an updated frequency response model (FRM) for modern power grids incorporating a grid-forming (GFM) converter. This model aims to accurately capture the dynamic frequency behaviour of the GFM converters integrated into large-scale power systems. To achieve this, this paper estimates unknown parameters of the updated FRM to ensure a frequency response that closely matches the behaviour of the actual power grid. The updated FRM comprises two interconnected areas: the aggregated synchronous generator (ASG) area and the aggregated grid-forming (AGFM) area, linked by a virtual power synchronising interface. The parameter estimation is conducted using a curve-fitting-based methodology applied to frequency deviation data. First, the moment of inertia of each generation unit is determined based on observed frequency and active power deviations. Subsequently, the total load disturbance is estimated using the computed inertia values and the centre of inertia frequency deviation. Finally, the AGFM parameters including virtual damping, droop coefficient and virtual interconnection are estimated based on the ratio of the AGFM to the ASG speed deviations. The accuracy and effectiveness of the parameter estimation approach for the updated FRM are validated through simulations on a modified IEEE 39-bus test system using MATLAB/Simulink environment.