The Suppression Of Subsynchronous Resonance Simulation Study Based On The Coaxial Double Fed Motor

Construction of large-capacity steam turbine-generator units and transmission system with a high level of series compensation is an objective demand of China’s power industry development, using series capacitor compensation is an effective method to improve transmission line capacity, control the power distribution between the parallel lines and enhance power system transient stability, but series capacitor compensation may be caused the coupling interaction between the turbine generator shaft and the transmission network, resulting in subsynchronous resonance problem. Therefore, the research subsynchronous resonance suppression measures are of great significance.This thesis will take subsynchronous resonance suppression measures as basic research contents, mainly uses the time domain simulation method based on PSCAD/EMTDC to establish the system simulation model; proposed application of coaxial double fed motor suppression method of power system subsynchronous resonance, in order to achieve the goal that the coaxial double fed motor can effectively inhibit subsynchronous resonance when the unit in different operating conditions.Steam turbine generator with double fed motor shaft coaxial is the foundation to realize double fed motor suppression subsynchronous resonance, for the question that PSCAD/EMTDC component library comes with a shaft model is unable to realize the coaxial shafting, through the simulation contrastive analysis, using the Fortran programming language to establish the coaxial shaft model.Through the thorough analysis of the operation status after the coaxial double fed motor access system to clarify the basic principles that the coaxial double fed motor inhibition of the subsynchronous resonance. Based on the doubly fed motor mathematical model and its stator and rotor side converter control principle, established the double fed motor’s stator side and the rotor side converter control system in PSCAD/EMTDC, achieving the respective control objective. This thesis further focuses on the process of a supplementary subsynchronous damping control strategy, and points out that supplementary subsynchronous damping control strategy is a key factor of the doubly fed motor to achieve the inhibition of subsynchronous resonance.According to the actual parameters of the IEEE first bench mark model and a power plant series compensation transmission systems in China, this thesis builds a stand-alone system and multi-machine system time domain simulation model, respectively. For the three situations that doubly fed motor rotor not with AC excitation control, doubly fed motor with no strings attached damping control and supplementary subsynchronous damping control, taking a specific simulation analysis; The simulation results show that the application of the proposed supplementary subsynchronous damping control strategy, the doubly fed motor can effectively solve the system subsynchronous resonance problem.