The structure

control logic

operation

test

and application situation of an inner-positioned automatic quasi-synchronous system used for 330 MW unit no.8 in Huaneng Haikou Power Plant

which is constructed by bringing the automatic quasi-synchronous system into DCS

have been presented.A comparison with the traditional single-purpose synchronous system shows that the inner-positioned synchronous system in DCS has advantages of few external cables

small investment for equipments

and little amount of installine works etc.

but it has shortcomings of non-adjustable pulse width for output commands

and negative values are included in settings of frequence difference and voltage difference.