Artificial Commutation of Converters Through Injection Technique

The conventional converter consumes reactive power by virtue of the lagging power factor inherent in normal operation. Operation at leading power factor requires commutation in the region (α+
_u
) > π. This can be achieved through artificial commutation by reversing the valve-to-valve voltage during the commutation period. In a two-converter station the vars so generated can be supplied to a conventional converter operating in parallel on the ac side and, ideally, the station capacitive reactance can be reduced to that required for satisfactory harmonic filtering.