Study On Generator Terminal Side Damping Control Strategy And Its Impact On SSR

In Modern power systems, large turbine-generator rotor shaft has significant flexibility. Under certain conditions, it will be the torsional vibration for mechanical and electrical interactions. When there are series compensation capacitor in the AC transmission line, it may arouse subsynchronous resonance (SSR). Great harm wil happen caused by SSR. Generator rotor shaft will be affected by fatigue damage becouse it is repeated under great torque, resulting in reduced its life, severe cases may cause cracks or shaft fracture leading to affect the normal generator run and threaten the safety operation of the power systems. In Inner Mongolia Shangdu transmission engineering, it appears SSR by using the higher compensation degree fixed series compensation device. Through research and analysis, decision to take generator terminal side damping controller(GTSDC) to suppress SSR.GTSDC is a sub-synchronous resonance suppression device, it connected to the generator terminal voltage bus on the bus or the power plant. It is based on the feedback reflects the shaft torsional vibration signal to dynamically generate the compensation current reference value, through the power electronic devices (This paper will use STATCOM) generate the sub (super-) synchronous current into the unit or grid, thereby strengthening the sub-synchronous damping torque.Based on mathematical modeling, this paper establishs simulation model using actual project data on RTDS. Based on control objectives of the GTSDC and mathematical model of the STATCOM, this paper designs control strategy of the GTSDC, and then demonstrated the correctness of the damping controller control strategy and suppression effect for SSR by using RTDS.