Study On The Quantitative Assessment Of SSR And Analysis Of Control Characteristics On The GTSDC

Series compensation in long-distance transmission system is an effective method to increase transmission capacity and improve the stability of the system. But when the resonant frequency of the grid is close to the complementary frequency of generator shaft torsional vibration,the torsional vibration leads to sub-synchronous resonance (SSR),and damages the security of generator and stability of the system. Therefore, the SSR risk assessment and suppression measures are essential for the transmission system with Series Compensation Capacitor.(1) A new approach integrating frequency-scanning and complex torque coefficient is proposed in this paper to quantitatively evaluate subsynchronous resonance (SSR) of practical series-compensated power systems. It first uses frequency-scanning to obtain an equivalent model and its parameters of the target system. Then an explicit expression is derived for the modal damping, in which both mechanical and electrical damping is included. The proposed approach is verified with two case studies. The results demonstrate its consistence with the eigenvalue analysis. However, the new approach is concise in principle and has less computation. Further it relates SSR risk with system parameters directly, presenting a quantitative and accurate index of SSR risk in multimachine series-compensated power systems.(2) Using eigenvalue analysis to analyze and verify the control characteristics of GTSDC. Firstly,the basic principles of GTSDC is explained clearly ,and the detailed linear model of open-loop transmission systems and GTSDC are established. Secondly, using eigenvalue analysis analyzes the Series Compensation Capacitor change with the real of eigenvalues in open-loop system, and adding additional excitation damping controller SEDC or the common role of SEDC and GTSDC, then the suppression ability and control characteristics is compared and verified.(3) Simulation study of the GTSDC control effect. A suppression method integrating TSR, SEDC and GTSDC is proposed in this paper to remove multimodal SSR. A number of simulation results show that the system work together in the TSR and SEDC required to cut the two planes, while the only one machine was cut in the component of TSR,SEDC and GTSDC...