Power System Inertia Estimation Method Based on Energy Conservation

Aiming at the inertia estimation method based on unbalanced power and rate of change of frequency (ROCOF) at the initial moment of the disturbance, the inaccurate measurement of ROCOF brings large error to the system inertia estimation. In this paper, the form and index of system inertia are firstly sorted out, and an inertia index that can accurately express frequency change characteristics under disturbance is proposed. In terms of inertia estimation, the estimation process is extended to frequency nadir. By analyzing the power response and energy conversion mechanism during disturbance process, a system inertia estimation method based on energy conservation is proposed. The relationship between primary frequency regulation power of generator and ROCOF are used to linearize the primary frequency regulation power. Finally, the effectiveness of the proposed method is verified by modified WSCC 9 Bus Test Case. At the same time, the proposed method is also applicable to the frequency of non-center of inertia (COI), making the model more applicable.