As the lowest layer in whole control system and the
directors for all kinds of instructions, this layer controls the
valves that are in VSC converters, Valves control layer
produces the corresponding trigger pulses in line with the
control instruction from the converter control layer, which
make opening or shutting off the valves, so as to reach the
control purpose. Valves control layer feedbacks the
corresponding information to the converters control layer and
monitors the state of the valves and determines whether
working normal. Once the short-circuit fault appear in valves,
it can blockade pulse and protect the devices itself, and then
triggers the control protection.