Optimization of the thyristor valves design for TCR static VAr compensators

The authors developed a digital program to optimize the design of thyristor valves for thyristor controlled reactors (TCR) with fixed capacitor banks. This program will be used in the future as a subroutine of a complete SVC optimization program. The design of thyristors valves basically consists of the choice of the thyristor, the design of the snubber circuit the design of the refrigeration system and choice of the overvoltage and overcurrent protection. For a specific power system and design criteria there are many possible designs with different costs. Therefore, it is important to have a tool capable of giving an indication of the best one. As an example of application, the authors present the results of the use of this program for the optimization of a TCR of 5 MVAr capacitive and 15 MVAr inductive to be connected on the 13.8 kV tertiary of a 30 MVAr existent transformer. This example was used to verify the influence of different design criteria on the cost of the SVC and its results will be used by the Brazilian utilities to make further specifications