Study of Black Startup Strategy of The Turn-off Device Based Current Source HVDC Converter

The turn-off device based current source converter (TOD-CSC) is a promising circuit topology in high voltage direct current (HVDC) transmission systems. Compared with the conventional line-commutated converters (LCCs) the controllability of TOD-CSC is dramatically enhanced, while the cost and complexity are reduced compared with voltage-source converters (VSCs). However, for many applications, such as renewable energy generation systems, the black startup of TOD-CSC is a big challenge. In this paper, the mechanism of the black startup of TOD-CSC for passive networks are analyzed first. A segmented black startup strategy is proposed for TOD-CSC. Simulation results on a TOD-CSC based 120 kV/240 MW back-to-back HVDC transmission system in PSCAD/EMTDC environment show the correctness of the proposed black startup strategy.