APPLICATION OF MULTIVARIABLE CONTROL FOR AUTOMATIC FREQUENCY CONTROLLER OF HVDC TRANSMISSION-SYSTEM

In an HVDC transmission system that links two ac power systems, the au tomatic frequency controller (AFC) calculates power to be interchanged between the two ac systems according to their frequencies thereby imp roving the frequency characteristics of the two power systems. This pa per introduces a newly developed dc AFC system, which applies a multi- vaxiable control to the dc system-based frequency control. It is capab le of controlling the frequencies of the two ac systems optimumly whil e maintaining their stability. This system was developed for one of Ja pan's HVDC transmission facilities and produced good results in a comb ined test using a power system simulator. The field installation will be completed in March 1993, when the AFC system will enter service.