Application of multi-variable control for automatic frequency controller of HVDC transmission system

In an HVDC transmission system that links two AC power systems, the automatic frequency controller (AFC) calculates power to be interchanged between the two AC systems according to their frequencies thereby improving the frequency characteristics of the two power systems. This paper introduces a newly developed DC AFC system, which applies a multi-variable control to the DC system-based frequency control. It is capable of controlling the frequencies of the two AC systems optimumly while maintaining their stability. This system was developed for one of Japan´s HVDC transmission facilities and produced good results in a combined test using a power system simulator. The field installation will be completed in March 1993, when the AFC system will enter service