Abstract: The VSC-HVDC （voltage source converter based high voltage direct current transmission） system has a good application prospect in supplying power to the passive network. Firstly, this paper analyzes the system structure and working principle of VSC-HVDC in passive network power supplying and develops its Euler Lagrange （EL） model in d-q synchronous reference frame. At the same time, two controllers including a PI double closed-loop controller and a passive double closed-loop controller are designed. Then, this paper presents the parameters tuning method of outer-loop controller based on the symmetrical optimum method. Under different operating conditions including power change of passive network and voltage drop, VSC-HVDC system with a PI double closed-loop controller or a passive double closed-loop controller is simulated by software PSCAD/EMTDC. The simulation results show that the proposed control parameter tuning method is correct, the designed passive double closed-loop controller and PI double closed-loop controller can realize the fast and precise control of voltage and current, and the voltage of the passive network can be stabilized at a given value. Relatively speaking, the dynamic performance of passive double closed-loop controller is better.

Key words: voltage source converter based high voltage direct current transmission （VSC-HVDC）, passive network, passive controller, double closed-loop control, PI parameters tuning