The Analysis Of Power System Subsynchronous Oscillation Based On The Bond Graph

With the development of our interactive electric grid in recent year, especially the widely application of the thyristor controlled series compensation (TCSC) and high voltage direct current (HVDC) transmission, the importance and urgency to study the problem of SSO (subsynchronous oscillation) of power system is becoming particularly outstanding. The subsynchronous oscillation of power system is a kind of special phenomenon of electromechanical coupling interaction, that refers to complicated multi-energy system, and the tradition analysis method is less convenience.The bond graph theory is a modeling method suitable for the multi-energy system, and based on the energy conservation,that can transform one kind of energy system model to another equivalent energy system model. That is very convenience to analysis and study in the same energy system, and provide a facilitate tool to the multi-physics system modeling. This paper uses the bond graph theory to analyze the shaft oscillation of the subsynchronous oscillation, that is convenience for analyzing the related issue of the subsynchronous oscillation. Bond graph theory itself has definite topology structure and established the mathematical model of the systematic approach in the multi-energy system has extensive applicabilityThis paper proposes a method which based on the bond graph theory to analyze and simulate the SSO. The bond graph model of turbine generator unit shaft system is established by using this method, and the equivalent circuit model of turbine generator unit shaft system is proposed. It is convenience to analyze the shaft torsional oscillation directly when combines the other electric block to simulate the dynamic process of the SSO.Case studies using the model, which is the IEEE about the first benchmark model for computer simulation of subsynchronouse resonance, and combining the simulation of PSCAD/EMTDC for comparison. That proves the validately and accuracy of the proposed shaft system model based on the bond graph.