Improved Complex Torque Coefficient Method Using CPCM for Multi-Machine System SSR Analysis

Calculation of the complex torque coefficient for multi-machine system subsynchronous resonance (SSR) assessment had been proven a hard task. In this paper the concept of complex frequency domain port-equivalence conductance matrix (CPCM) is introduced to model the individual system component which represents the relationship between the terminal voltage and current in frequency domain, and the model of the overall power system can be established easily. Thus the complex torque coefficients of the generator unit under investigation can be calculated for SSR assessment. The advantages of this proposed method are that it can take the shaft dynamics and the rotor angle interactions among the generator units into consideration for the multi-machine power system SSR analysis, as well as it can be used to analyze the effectiveness of SSR damping devices. The effectiveness of the proposed method has been verified by both the eigenvalue analysis and the time domain simulation.