Online Thevenin Equivalent Parameter Identification Method of Large Power Grids Using LU Factorization

Real-time tracking and identification of Thevenin equivalent parameters is crucial for voltage stability online monitoring of large power grids. An online parameter identification method based on wide-area measurements and nodal analysis is proposed in this paper. The node-voltage equation is utilized directly, and the open-circuit voltage is calculated accurately as the Thevenin equivalent voltage of load buses. Moreover, the equivalent parameters can be identified precisely under the generator reactive power over-limit condition. To avoid repetitive Gaussian elimination of the high-dimensional linear system, lower upper factorization and optimized substitution are used to accelerate the open-circuit voltage solution process. The simulation results of multiple test systems demonstrate the accuracy and rapidity of the proposed method.