A hybrid fuzzy-PI controller for voltage source

converter based HVDC (VSC-HVDC) transmission system is

proposed in this paper. At first, the elementary model of VSCHVDC

is described. Then the fuzzy self-tuning control strategy is

proposed, in which direct current control strategy and dual

closed loop structure are designed in dq synchronous reference

frame. Independent control of the active and reactive power is

realized. Simulation results show that the designed control system

obtains satisfying performance, and the adjustments of power

flow could be achieved quicker than convention PI control.