Flexible AC Transmission System (FACTS) system studies: Southern Company services

The objective of the study is to evaluate the dynamic performance of the transmission interface between Southern Company (SC) and Florida Power & Light Company (FPL) as it is affected by the addition of reactive compensation to the existing 500 kV tie lines. The focus of this study is on the voltage stability of the interface, and the dynamic performance of the two interconnected systems under conditions of voltage stress. The potential to increase transfer on the interface through the addition of series compensation is examined. The intent is to provide quantitative insight into performance, and to explore how Flexible AC Transmission System (FACTS) controllers might be employed to improve that performance. Consideration of the economics of the reinforcement is made. The use of series compensation is demonstrated to allow a substantial improvement in the power transfer capability and loss of performance of the system. The possibility of including Thyristor Controller Series Compensation (TCSC) in a voltage regulating mode is introduced. One significant benefit of this is to permit using larger series compensation banks than could otherwise be allowed using only conventional series compensation in a single site. This result has significance since this introduces the potential for utilities tomore » develop fewer sites than might otherwise be required. It is shown that, even though a conventional compensation plan may be the preferred option for this specific application, a TCSC-augmented approach could be the preferred option in other situations. In addition, a TCSC-augmented approach may be preferable for systems where improved voltage controllability, reduced SSR risk, and better system damping, are significant. The results indicate that TCSC is a viable option for utilities whose operating constraints tend to be voltage and postcontingency power flow, as well as systems with faster dynamic concerns.« less