APPLICATION OF AN OPTIMAL CONTROL STRATEGY TO A NEW TYPE OF HVDC SYSTEM BASED ON VOLTAGE SOURCE CONVERTERS

Comparing with traditional HVDC system the merits of a new type of HVDC system based on voltage source converters (VSC) and pulse width modulation (PWM) technologies is expounded. On the basis of establishing the model of parallel AC/DC transmission system an optimal control strategy is proposed in which the control of HVDC system itself is integrated with the control of generator excitation, when fault occurs in the system the generators and the HVDC transmission can be stabilized at the same time. The new type of HVDC system based on VSC and the traditional HVDC system are simulated under the same conditions, the simulation results show that by use of the proposed optimal control strategy the former possesses a better damping characteristic under the fault, and the former itself also possesses better stability with this control strategy being used.