GPS/AM/FM/GIS Y2k Info Needed!

greenspun.com : LUSENET : Electric Utilities and Y2K : One Thread

Folks,

The following question was forwarded to me, and is well outside of my area of expertise. Can anyone field this one??

>In research of the Y2K situation I have found mention of GPS receivers
>being used by the utility companies.  If they are using the GPS time
>hack for grid synronization and their receivers are not able to
>correctly calculate the time when GPS goes to "Week 0000" on Aug. 21/22,
>1999, is it not possible that the grid will collapse at that time?  As
>the phase angles of the generating plants start to differ will they not
>cancel each other out?  I have not heard this discussed, but it does
>seem to be a possibility. 

Comments? Input? (BTW, I am familiar with GPS issues; just not all of the impacts on the electric business.)

-- Anonymous, March 09, 1998

Answers

Mr Cowles, It has been several weeks since I sent this question to you and Mr. Martin. I hope you can find someone in the "Closed" forum that has some idea if this is or is not a threat to the system. Thank you for your efforts, Bill King

-- Anonymous, March 25, 1998

When I respond to a message in this forum, for some reason (because I'm the forum administrator, I guess) my responses go up front and have a tendency to get out of chronological order.

THIS RESPONSE IS FOR MR. KING'S MESSAGE, BELOW

Three quick things up front:

1) Please understand that everything I do with this website, including research for you, I'm doing on my own time (it's now 9:30PM EST). Sometimes I'm not able to devote as much time to research as I'd like. That's why I try to engage other people who might be more knowledgeable than myself in a particular subject matter area.

2) Again, I'm not an expert in this area. In the absence of any cogent responses from those more knowledgable, and in the interest of providing you a response, I'm going to take a stab at it.

3) The closed forum is for industry personnel only. I don't post there, so won't repeat the GIS/GPS question there. Hopefully, someone from that forum who also lurks here will pick up on my attempt at a response and correct me where I'm wrong.

That being said...

GPS is used within the electric industry primarily in GIS (Geographic Information Systems). GIS is used in a variety of applications - two areas that I'm familiar with are service vehicle onboard customer locator systems and within transmission / distribution departments in EMS (energy management systems). I don't believe that the functionality of either of the above business areas is absolutely dependent on functioning GPS/GIS systems. In other words, these business areas and power delivery CAN function w/o GPS/GIS.

Specific GIS systems receive input from system GPS receivers. The ability of GIS systems to operate post-GPS week 0 rollover (August, 1999) is dependent on the ability of the GIS system's GPS receiver to correctly interpret the GPS rollover to week 0. It's got nothing to do with GPS satellite operation, as I understand it.

Again, (DISCLAIMER), this is not my area of expertise. I'd be very curious to know myself if/why any power quality attributes could be affected by a malfunctioning GIS system.

-- Anonymous, March 25, 1998


Dear Mr. Cowles, I certainly understand the time requirements involved in the task load that you have thankfully agreed to assume. I also thank you for the time spent and the frank answer you have provided. Regards and thanks again, Bill King

-- Anonymous, March 26, 1998

GPS receivers, WWV receivers, and IRIG B signals are not used to synchronize the grid. Synchroscopes and Synchrochecks relays are used for that and they don't have clocks in the sense that you are thinking about. In fact synchroscopes have no clock at all. The time of day receivers are used to synchronize time-stamping of alarms and events and for sequence of events recorders. The grid is self synchronizing. Once a generator is attached to the grid, the frequency of the grid must be followed. No single generator can resist the grid. In fact, in those instatnces that generators are closed in 'out-of-sync' by any large amount, it sometimes results in physically ripping the multi-ton generator off its mounting pads and throwing it. That almost never happens but I have been told that it is quite a spectacle.

-- Anonymous, April 06, 1998

Indeed, Steve, I'm sure that would be quite a spectacle. I've seen 25Kv to 500Kv stepup transformers blow; I've seen the results of turbine blades flying through casings, but have never seen the launch of an entire machine!

-- Anonymous, April 08, 1998


There is a new application for GPS that involves direct measurement of the phase difference between AC waveforms at widely distributed locations, (i.e. hundreds or thousands of miles). So far it's experimental and a novelty so it hasn't found its way into anything critical to my knowledge.

Any part of an AC grid connected to any other part is in syncronism with the other part, all without the aid of computers. We've been doing that for over 100 years.

-- Anonymous, April 10, 1998


I have discussed this GPS Rollover problem with some friends working on the FAA's Enroute and Terminal Modernization program, over 2 yrs ago. According to these few individuals, the FAA and most of the aerospace industry has been fully aware of this GPS problem for some time prior to my queries. This awareness was due, in some large part, to the GPS industry who has, again according to a small sample of folks, known about this problem for at least several years and has taken noticeable steps to either fix existing (in the field) problems and/or to replace problematic units/systems with corrected ones. All of this is 2nd hand info, from a small sample, but from folks whom I have a high degree of respect for. Use the above accordingly. I am no GPS expert nor am I involved in any way with that technology or that industry. My only advice would be to contact your GPS supplier if your systems , whatever they may be, use GPS info/hardware and ask them if all is OK. Depending on their answer and your confidence in their answer, you may wish to take further action.

-- Anonymous, August 07, 1998

The original question about GPS dependence in electrical utilities seems to be answered. Where would there be a forum to ask about GPS dependence in oil production / pipelines, coal production, or rail/shipping transportation systems? Or in telecommunications itself?

Thanks!

-- Anonymous, August 24, 1998


The Grid is controled by inputs from GPS Syncronous Clocks. How do you think a we know what 60hz is? If the input from the clock goes away not only will the Area Generation Control system have a problem. But also in the case of our EMS system the EMS Cyber would loose it's clock signal causing a CRASH! We are fully compliant with our True Time GPS Clocks... Esteban http://home1.gte.net/esteban/GPSBUG.htm

-- Anonymous, August 24, 1998

Moderation questions? read the FAQ