white@cogito.dec.com (Robert V. White MLO6A-3/T96 223-7647) (05/09/87)
> Path: decwrl!decvax!ucbvax!ucbcad!ames!hc!beta!cmcl2!phri!roy > Subject: Re: Syncronizing Generators > A good question to ask is "with all these random (albeit >synchronized) generators all over the place, what's to keep the grid >frequency from drifting?" The answer is that somewhere on the grid, >somebody is monitoring the line frequency, and comparing it to a standard >(WWV, probably). >Roy Smith, {allegra,cmcl2,philabs}!phri!roy I believe that the monitoring is done by American Power Corporation in Canton, Ohio using a Cesium time standard. Bob White Corporate Power Conversion R&D Digital Equipment Corporation Maynard, Massachusetts
larry@kitty.UUCP (Larry Lippman) (05/10/87)
In article <9779@decwrl.DEC.COM>, white@cogito.dec.com (Robert V. White MLO6A-3/T96 223-7647) writes: > > A good question to ask is "with all these random (albeit > >synchronized) generators all over the place, what's to keep the grid > >frequency from drifting?" The answer is that somewhere on the grid, > >somebody is monitoring the line frequency, and comparing it to a standard > >(WWV, probably). > > I believe that the monitoring is done by American Power Corporation in > Canton, Ohio using a Cesium time standard. I believe that most power plants also maintain a local frequency standard, with a long-term deviation recorder. I have seen such devices in fossil-fueled plants (I have never been in a hydro or nuclear plant). There is a strip-chart recorder which continuously records +/- deviation from 60 Hz. In one plant that I saw, the reference frequency was provided by a Tracor frequency standard with a WWVH receiver. There is apparently a certain amount of local power plant "leeway" in providing frequency compensation to assure long-term 60 Hz accuracy; i.e., the local plant can operate "off frequency" to a limited extent (fractions of a Hz) in order to provide compensation, with such off frequency compensation still not resulting in excessive power loss to the grid. Frequency compensation is usually provided during off-peak hours. The algorithm is simple: the minus deviation is continuously integrated and compared with the plus deviation, and once a day during off-peak hours a compensating deviation is computed to run the plant for a given period of time at a given frequency. <> Larry Lippman @ Recognition Research Corp., Clarence, New York <> UUCP: {allegra|ames|boulder|decvax|rocksanne|watmath}!sunybcs!kitty!larry <> VOICE: 716/688-1231 {hplabs|ihnp4|mtune|seismo|utzoo}!/ <> FAX: 716/741-9635 {G1,G2,G3 modes} "Have you hugged your cat today?"