As the highest control layer in whole control system, the
DC system control layer receives the control instruction
information from the center of the power dispatch and
feedback operation messages from the pole control layer and
then judges the operation messages reach the requirement
which the power dispatch center asked. In addition to
combining with the electric parameters information of AC bus
node connected with the VSC-HVDC system, and adjusting
real-time the instructions for pole control layer. In the process
of study on the control strategy of this layer, it is necessary to
consider many factors, such as the network trend distribution,
the stable requirement of the system. For and improving the
AC system operation character, and the reliability of the
system, it is required to design the appropriate control strategy
and make use of the fast regulate characteristic of VSC-HVDC
system. DC system control layer of VSC-HVDC is able to
control operation mode, trend reversal, and other kinds of
modulation.