Design, simulation and comparison of synthetic test circuits for extra high voltage circuit breakers

Development in electrical power transmission system requires the use of circuit breakers with increasing breaking capacity. At present circuit breakers are to be installed on 245 kV to 760 kV power system with short circuit ratings up to 63 kA. To test high voltage CBs, direct testing using the power system or short circuit alternators are not feasible. The testing of high voltage CBs of larger capacity requires very large capacity of testing station. To increase testing plant power is neither an economical nor a very practical solution. Therefore indirect methods of testing are used for testing of large CBs. Synthetic testing is an alternative equivalent method for testing of high voltage circuit breakers and is accepted by the standards. Parallel current injection synthetic testing is the most widely used method for testing of CBs. This paper presents a comprehensive review of TRV rating concepts, standard TRV envelopes, types of synthetic test circuits used for high voltage circuit breakers. Design and simulation of 4-parameters TRV synthetic testing circuits is done by using PSIM simulator. Three different 4-Parameters TRV circuits are simulated for a 420 kV rating circuit breaker for comparison purpose. Design optimization is also done to reduce the energy required by the capacitor banks. The results obtained by using different circuits have been discussed in the paper. The comparison is made on aspects of equivalence, operation, required capacitive energy and applicability. The comparison shows that although each circuit has its own merits, the Weil Dobke circuit appears to be very effective and is better than other circuits.