Principle Of Subsynchronous Resonance Analysis And Study Of Mitigation Method

Large-capacity and long-distance transmission is the necessary demand of theelectric industry development of our country, and series compensation technology is aneffective way to enhance the long-distance transmission ability and the stability of thesystem. However, if the resonance frequency of series compensated transmissionnetwork and the natural frequency of turbine-generator shaft complement each other(the sum is equal to synchronous frequency), it may result in SubsynchronousResonance. It is a serious threat to the power system stability and the safety of the rotorshaft.Beginning with Subsynchronous Resonance three big problems (Inductiongenerator effect, Mechanical and electronic reverse interactions, Transient shaft torqueamplification), this paper detailed illustrates their occurrence process and influence, andsimply introduces Subsynchronous Oscillation problem of High Voltage Direct CurrentTransmission System (HVDC). This investigation is done based on the IEEE FirstBenchmark Model and shafting model. Turn-off pulse generator with zero crossingdetectors is used for Gate-Controlled Series Capacitors controlling in order to dampSSR and has been verified through the simulation.Because there are a variety of solutions of the shortcomings, this paper willintroduce delay feedback control theory (DFC) into electric power system protectionand control. Through the establishment of power system, shaft system and delayfeedback control system, the stable time delay parameter of the delayed feedbackcontroller is managed by means of employing the Cluster Treatment of CharacteristicRoots (CTCR) and Routh Listing. At last, using Simulink for a point in the stable timedomain confirm its feasibility. It shows that delayed feedback control system caneffectively decrease distortion force because of Subsynchronous Resonance.