Mojtaba Khederzadeb - Power & Water Institute of Technology (PWIT) Tehran, IRAN.
Hossein Ansari Shabrezei - Iran Power Develeopment Company (IPDC) Tehran, IRAN.

variety of FACTS devices are now being proposed as a means of increasing the capacity and flexibility of the power system. Thyristor Controlled equipment is one of the major sources of harmonics in power systems impacting power quality. Power quality and system protection are related in several ways that might not be immediately apparent. Protective relays have better discrimination when power quality is good. When power quality is poor, the threshold between normal and fault conditions become blurred. In this paper, Thyristor Controlled Series Capacitor (TCSC) installed by power utilities to increase power transfer capability of transmission lines is investigated in terms of harmonic distortion in the power system and its effect on the protective relays behavior. The power quality is evaluated by EMTP/ATP simulations and the relay behavior is investigated by a digital relay simulator prepared in the MATLAB environment.

Harmonies, Power Quality, Power System Protection, Thyristor Controller Series Capacitor (TCSC)