| Abstract |
This paper deals with thyristor valves used for SVC on Transmission Networks. Each Static Switch is made of several series connected thyristor levels, which number is proportional to the required voltage withstand. This voltage value depends on transient stresses. In order to satisfy more and more severe operation conditions, a special protection design has been built up. This results in improved reliability and dynamic behaviour, less thyristor levels put in series and lower electrical losses. After a short description of SVC system and valve design, will be introduced steady-state stresses on Thyristor Control Reactors (TCR) or Thyristor Switched Reactors (TSC) and then on Thyristor Switched Capacitor (TSC). Next will be described the protective system design and transient stresses in relation with this protection operation. Some emphasis will be made about HV line switchings on weak systems or networks, for which a SVC can be a conclusive solution. |
