By the characters of the VSC-HVDC system, nowadays, it
has been widely used in synchronizing the passive network,
clean energy, such as wind power, solar power. There are
many projects as VSC-HVDC system in the world, and the
flexible HVDC project of Shanghai Nanhui wind station which
has the completely independent intellectual property rights and
world-class level successfully commissioned on 3rd May 2011
in China. There are more and more scholars paid high attention
to the VSC-HVDC control system [2-10]. But many of
research are in the Control strategies of control system, little in
the control system structure. The paper [11] discussed in detail
about the design and functions of VSC-HVDC system, and
introduced the control platform MACH2, but it didn’t point out
that the necessary of stratification and the relations between
the layers. The papers [12-13] just simply pointed out that the
VSC-HVDC control system is composed of pole control
(converters control) and valve control units. The paper [14]
divided into four layers to VSC-HVDC system but neglected
the pole control layer