Bipolar Cascaded Modular H7 Current Source Converter for HVDC Grid With Simple DC Fault Ride Through Capability

Nowadays, one of the major challenges to developing the high voltage direct current (HVDC) grid is the effective and economical dc fault protection technique, which is normally realized by the dc circuit breakers (DCCBs). However, the DCCB is quite complex and expensive. Therefore, to explore an alternative solution, this article proposes a bipolar cascaded modular H7 current source converter (CSC) for an HVDC grid with simple dc fault ride-through capability and then analyzes its dc fault behavior and consequently proposes the protection scheme, which can reduce the design requirement of DCCBs, even handle dc faults only with mechanical switches. Power systems computer-aided design (PSCAD) simulation and experiment results are demonstrated to validate the feasibility of the proposed topology and fault protection scheme.