Research On The Control Strategy Using FACTS To Restrain SSR

The series capacitor compensation, which is an important measure as the improvement of the transimission line's transimission ability, has been more and more emphasized in power network planning in our country. But after the series capacitor compensation is used in the extra-high voltage long distance transimission system, in a certain operation mode or compensation degree, sub-synchronous resonance(SSR) will occur. SSR is a very dangerous state which may occure in power system operation. When the electric resonance frequency approximatively adds one of the inherent surge frequency of synchronous generator axis. The coupling surge of electric-machine system will occur, the serious accident is the synchronous generator axis will be twist off and the grave economy loss will be result in. Therefore, the research on the SSR which is produced by the series capacitor compensation and countermeasures to prevent its electric-machine resonance is one of an importment subjects in the safe and stable operation of power system.Flexible AC Transmission System (FACTS) will be widely used in power system, it is one of the burgeoning subjects of power system in recent years. As the fast and flexible adjustment ability of FACTS equipment, many application fields of power system have pay more attention to it,and it provides useful tools to restrain SSR. Thyristor Controlled Series Compensator (TCSC)and Static Synchronous Compensator are the importment elements of FACTS family. Each of them is the typical representation of series compensation equipment and parallel compensation equipment. Therefore, the research on TCSC and STATCOM has comparatively large theory meaning and practicability value.With TCSC and STATCOM are established as the studying object, the basic principle of SSR of synchronous generator is analysed in this paper firstly, then according to the working principle and mathematic model of TCSC and STATCOM, the mechanism of TCSC restrains SSR and the control strategy of STATCOM is put forward, and the numerical emulation is done.Assuming that the fundamental frequency component and the sub-synchronous frequency component of voltage across TCSC can be decoupled, the equivalent sub-synchronous frequency impedance of TCSC is formulated under the circumstance that a tiny sub-synchronous frequency component adds to the fundamental voltage. On...