Operational tests on HVDC thyristor modules in a synthetic test circuit for the Sylmar East Restoration Project

According to IEC 700 and IEEE 857, operational tests on HVDC thyristor modules can be performed either in a six-pulse back-to-back test circuit or in a synthetic test circuit. Because of the high rating of modern thyristors the use of a six-pulse bridge configuration would require facilities with a high installed capacity. In a synthetic test circuit even high current and voltage stresses can be represented using less than 1/100 of that installed capacity. Thus, synthetic test circuits are an economical alternative to test a representative part of a modern thyristor valve. The paper describes the operational tests on thyristor modules for the Sylmar East Restoration Project which were completely carried out in a synthetic test circuit.