• A sensitivity graph signal model for the protection coordination of the power grid is constructed. • The graph Fourier transform is used to assess the shift of the sensitivity centre of the protections. • An evaluation method for risk points and hidden faults in relay coordination is proposed. • The performance is validated on the distance relays of an actual 220 kV grid. To accurately identify risk points and analyse hidden faults of the time-step protection system, this paper proposes a sensitivity centre-based evaluation method. This paper constructs a sensitivity graph signal model for the protection coordination of the power grid by studying the change characteristics of the time-step protection sensitivity network. The graph Fourier transform(GFT) is used to extract eigenvalues and GFT coefficients of the proposed graph signal. The eigenvalues and GFT coefficients are used to carry out sensitivity centre analysis, assessing the shift of the sensitivity centre of the time-step protection under different operating modes. Using the results, accurate and quick identification of the risk points and hidden faults of the grid protective relay coordination is realised, as well as an auxiliary support for the evaluation of the grid backup protection scheme. The data in the time-step zero sequence protection and distance protection on a 220 kV grid in the field is used to test the proposed method. The correctness and effectiveness are verified.
Liao et al. (Mon,) studied this question.