Research on Centre of Inertia Based Frequency Sampling and System Frequency Distribution Characteristics

As the amount of new energy injected into the power system increases, the system inertia decreases and the spatio-temporal characteristics become apparent. Due to the uneven distribution of inertia in the power system, the dispersion of the frequency response after disturbance is more pronounced, and the inertia estimation error has a random nature when different frequency measurement points are selected. For the above problems, a method is proposed to select the frequency measurement point based on the centre of inertia. Firstly, based on the frequency dynamic response characteristics, the main influencing factors of the frequency distribution characteristics are studied and the spatial and temporal distribution characteristics of the frequency of the new energy power system are analyzed. Secondly, the method of frequency sampling through the centre of inertia is proposed with full consideration of the electrical distance and generator inertia constants. Finally, a 10 machine 39 bus system is simulated as an example. Simulation results show that using the centre of inertia as the frequency sampling point during inertia evaluation can reduce the inertia evaluation error by up to 16.15%. The results verify the correctness of the above theoretical analysis and provide a favourable basis for further improving the accuracy of the power system inertia estimation.