Study on the design and equivalence test methods of VSC-HVDC valves

The high voltage direct current transmission technology based on voltage source converter (VSC-HVDC) which employs voltage source converter (VSC), self-turn-off device and pulse-width modulation (PWM) technique. VSC can be categorized into two types as per its topology: one is multi-level converter which consists of series-connected self-turn-off devices, and the other is Modular Multi-level converter (MMC) which is made up of series-connected submodules whose major components are self-turn-off devices. To ensure safe operation, type testing of VSC-HVDC valves is essential before launching them. Substitute equivalence methods are always utilized for valve type tests. For different converter topologies, test objects and test methods are similar. This article begins with the studying of the two kinds of VSC-HVDC valve topologies, and then the electric structures are analyzed. Moreover, corresponding equivalence test methods are investigated, including valve stresses, test requirements, test items, and test methods.