A Research To Sub-Synchronous Resonance With Turbine-Generator

As the long-distance and large-capacity transmission is more popular in modern power systems, series compensation equipment is often used to keep system stability and utilize finite resource more economically and efficiently. Because much progress had been made on large power electronics, FACTS (Flexible AC transmission Systems) brought out the revolution of series compensation technology since 1980s. The research and application on this field become the foci all over the world. Furthermore, TCSC (Thyristor Controlled Series Compensation) is playing more important role. It is overviewed the analysis methods and countermeasures used to damp out the SSR and discussed the trends of SSR with the theoretical progresses in mathematics , the newly developed transmission and control technologies in power system. By use of Saber, the turbine-generator model based on magnetic saturation and 21shaft-mass is developed. Detail analysis and digital simulations are presented for suppression and counter measures of sub-synchronous resonance (SSR) in one machine infinite big system with series compensation. It was in doubt for long time whether the static-excitation could be used to improve Sub-synchronous Resonance condition in a certain power system with serial compensation. In this paper the problem above is studied theoretically, and it's shown that SSR probability will be depressed as static-excitation is used. SSR in series compensation systems will cause great damage to the shaft of generator. So there is a safe range of compensation. It is a common concept that TCSC can damp SSR efficiently and enlarge the range of compensation. Based on the TCSC mathematical model, capacitor voltage boost level, the open-loop current modulating algorithm and the capacitor voltage zero-crossing control algorithm is analyzed in details. By the way TCSC can damp SSR as the analysis of simulation result shown in chapter 4, but compared to open-loop control, PID control algorithm could control reactance with more precision and mitigate the SSR effectively.