Description of the Internal State of TCSC

ABSTRACT The description of the internal state of thyristor controlled series capacitor (TCSC) is presented in the paper. The model developed for this description is based on the firing angle of the thyristor. Simulations showed that the model is capable of identifying the internal state of TCSC. KEY WORDS FACTS, TCSC, Internal state of TCSC 1. Introduction Enhancing power transfer capability of existing transmission systems is one of the major challenges faced in power systems [1-2]. Flexible alternating current transmission system (FACTS) is an efficient means of tackling this challenge. With the help of FACTS, the steady state and transient stability margins of the transmission system could also be enhanced [1]. Among the FACTS controllers, thyristor controlled series capacitor (TCSC) is an important device. TCSC has the ability to smoothen or suppress power oscillations, improve transient stability, lessen sub-synchronous resonance and act as a fault current limiter [3-11]. In addition, its degree of compensation is not step-wise controlled rather a rapid, smooth and continuous control is implemented. However, TCSC modeling is not without its challenges. In [12], it was shown that TCSC has variant topology under different system operating conditions. Zhongdong