Converter valve design and valve testing for Xiangjiaba - Shanghai ±800kV 6400MW UHVDC power transmission project

Thyristor valve design merits are inherited and new developed high power rating thyristors are used in the valve design. The thyristor control unit (TCU) and snubber circuit are optimized for a high reliability and low loss of thyristor valves. Two 12-pulse converters are connected in series as one converter per pole. The converters use a double valve MVU structure. A careful designed rigorous type test program has been followed to verify the valve and converter design. A single valve is comprehensively dielectric type tested and operational type tested. High voltage valve hanging structure, low voltage valve hanging structure and MVU, plus the series connected valve simulator, are valve supporting structure dielectric tested and MVU dielectric tested. The test results indict that the valve voltage and converter design and protection are proper and there is a substantial margin in operation since, for most of the operational tests, the test parameters were globally more severe than specified.