Analytical Calculation of the Frequency Nadir in Power Systems Based on Virtual Inertia Constant of Grid-Following Energy Storage

This study presents the method for the frequency nadir in power systems based on the virtual inertia constantization of grid-following electrochemical energy storage that solves the problem of poor analytical computation of power system frequency response, since the virtual inertia of grid-following energy storage is the irregular time-varying parameter, it is not possible to directly aggregate and solve for the system equivalent inertia time constant. The method enables the aggregation and calculation of the system equivalent inertia time constant, while incorporating the energy storage frequency regulation response module into the SFR model for the analytical solution of the system frequency response characteristics. Finally, the accuracy of the method is systematically demonstrated through numerical examples.