Lights on wind turbines - all in sync, but how?
October 26, 2013 6:15 PM Subscribe
The Biglow Canyon Wind Farm in Oregon, south of the Columbia River, has around 200 wind turbines operating. A while ago I drove past this installation at night time and I noticed that all the lights on top of the turbines - to indicate their presence to aircrafts, no doubt - were blinking in a totally synchronized manner. How is that possible?
I was always under the impression that synchronizing lights would need to be done by a central mechanism since even the smallest tolerances of the electronics would over the course of time cause the lights to blink out of sync. Yet here we have 270 lights spread over a vast area, all in sync. Bonus question - why are they in sync in the first place? I know this is an odd ball question, but it just keeps coming up in my mind.
I was always under the impression that synchronizing lights would need to be done by a central mechanism since even the smallest tolerances of the electronics would over the course of time cause the lights to blink out of sync. Yet here we have 270 lights spread over a vast area, all in sync. Bonus question - why are they in sync in the first place? I know this is an odd ball question, but it just keeps coming up in my mind.
The easy answer would be the beacons are all powered off of the same blinking controller, like a giant string of Christmas lights. But that seems impractical.
What is probably happening is that the towers have some kind of clock synchronization. They have to have computers in them, and those computers have to be networked somehow. So getting a to the second time synch is no problem. Plus, they need to be synched up to the power grid anyway, so we know they have a 60 cycle per second "tick" source. So they will have no problem appearing to be perfectly in sync. Presumably whoever programmed the tower's controllers just built in the synchronization as an aesthetic feature.
posted by gjc at 6:24 PM on October 26, 2013
What is probably happening is that the towers have some kind of clock synchronization. They have to have computers in them, and those computers have to be networked somehow. So getting a to the second time synch is no problem. Plus, they need to be synched up to the power grid anyway, so we know they have a 60 cycle per second "tick" source. So they will have no problem appearing to be perfectly in sync. Presumably whoever programmed the tower's controllers just built in the synchronization as an aesthetic feature.
posted by gjc at 6:24 PM on October 26, 2013
Presumably whoever programmed the tower's controllers just built in the synchronization as an aesthetic feature.
I doubt it was for aesthetic reasons. If you were a low-flying aircraft pilot at night, would you rather see hundreds of disorienting randomly blinking lights spread over a vast area or synchronized lights that would give you an overall picture of the width and breadth and how to avoid it.
The turbines all have to be networked for both control and monitoring and also for synchronization to the grid. Synchronizing the beacons through the control network would be trivial.
posted by JackFlash at 6:51 PM on October 26, 2013 [1 favorite]
I doubt it was for aesthetic reasons. If you were a low-flying aircraft pilot at night, would you rather see hundreds of disorienting randomly blinking lights spread over a vast area or synchronized lights that would give you an overall picture of the width and breadth and how to avoid it.
The turbines all have to be networked for both control and monitoring and also for synchronization to the grid. Synchronizing the beacons through the control network would be trivial.
posted by JackFlash at 6:51 PM on October 26, 2013 [1 favorite]
Yeah such synchronization is not hard. At work we have computer systems spread all over the world that are kept in very tight sync - a microsecond or 2.
posted by RustyBrooks at 7:01 PM on October 26, 2013
posted by RustyBrooks at 7:01 PM on October 26, 2013
And they have to be synchronized anyway - they are expected to put out a 60hz AC signal. It's sort of bad if they are not working in unison.
posted by Pogo_Fuzzybutt at 7:21 PM on October 26, 2013 [1 favorite]
posted by Pogo_Fuzzybutt at 7:21 PM on October 26, 2013 [1 favorite]
I doubt it was for aesthetic reasons. If you were a low-flying aircraft pilot at night, would you rather see hundreds of disorienting randomly blinking lights spread over a vast area or synchronized lights that would give you an overall picture of the width and breadth and how to avoid it.
Excellent point! I'm sure that's the real reason.
posted by gjc at 7:26 PM on October 26, 2013 [1 favorite]
Excellent point! I'm sure that's the real reason.
posted by gjc at 7:26 PM on October 26, 2013 [1 favorite]
Best answer: Wind turbine guy here.
1) They use GPS to maintain sync; each light has a GPS receiver in it. See this datasheet (pdf) for an example. GPS has a highly accurate pulse per second signal, and they are way cheaper than cabling a separate synch line up every tower.
2) Because the FAA requires lights in a facility to be in sync. Pilots have to be able to see a group all at once to avoid it, hence they all have to flash at once. Plus, it helps limit light annoyance impact to neighbours.
posted by scruss at 7:26 PM on October 26, 2013 [28 favorites]
1) They use GPS to maintain sync; each light has a GPS receiver in it. See this datasheet (pdf) for an example. GPS has a highly accurate pulse per second signal, and they are way cheaper than cabling a separate synch line up every tower.
2) Because the FAA requires lights in a facility to be in sync. Pilots have to be able to see a group all at once to avoid it, hence they all have to flash at once. Plus, it helps limit light annoyance impact to neighbours.
posted by scruss at 7:26 PM on October 26, 2013 [28 favorites]
Response by poster: Thank you to everyone for your insights. I really appreciate it, now I can put this "pressing" issue to rest - in the hope that one day someone will ask me this very question :-)
posted by nostrada at 7:31 PM on October 26, 2013
posted by nostrada at 7:31 PM on October 26, 2013
To expand a little on scruss's answer, this FAA technical document reports on some test flights looking at lighting of wind farms:
Due to the random flashing (unsynchronized) nature of the obstruction lights, they could have been any group of light sources, looking particularly like a number of red stoplights on roads in the surrounding area. This effect was noted while viewing both wind turbine sites.
During subsequent low-level orbits around the Green Mountain facility, the team observed a momentary occurrence of all four light synchronizations. It was immediately apparent that synchronization of the obstruction lighting array increased the effectiveness of the lighting installation immeasurably and provided significantly improved information concerning the shape and extent of the wind turbine farm as an entity
and
random flashing metrological tower obstruction lighting array provided virtually no clue as to the location or extent of the wind turbine farm
posted by exogenous at 5:14 AM on October 27, 2013
Due to the random flashing (unsynchronized) nature of the obstruction lights, they could have been any group of light sources, looking particularly like a number of red stoplights on roads in the surrounding area. This effect was noted while viewing both wind turbine sites.
During subsequent low-level orbits around the Green Mountain facility, the team observed a momentary occurrence of all four light synchronizations. It was immediately apparent that synchronization of the obstruction lighting array increased the effectiveness of the lighting installation immeasurably and provided significantly improved information concerning the shape and extent of the wind turbine farm as an entity
and
random flashing metrological tower obstruction lighting array provided virtually no clue as to the location or extent of the wind turbine farm
posted by exogenous at 5:14 AM on October 27, 2013
Despite all of the GPS sync cleverness, sometimes you'll get a light that slips off sync with the rest. That usually requires you to climb the tower and check the status of the light controller, possibly power cycling it to get satellite sync again.
The FAA (and Transport Canada, to the somewhat annoyance of Nav Canada) now allow radar-controlled lights via Obstacle Collision Avoidance System (or similar). While these systems are expensive (and require a bunch of commercial radio licences), turbine lighting is a major concern to neighbours before a project is built.
(There are much cheaper visibility-based light dimming systems in development, but none that I know of have their FAA approval yet.)
posted by scruss at 7:46 AM on October 27, 2013 [3 favorites]
The FAA (and Transport Canada, to the somewhat annoyance of Nav Canada) now allow radar-controlled lights via Obstacle Collision Avoidance System (or similar). While these systems are expensive (and require a bunch of commercial radio licences), turbine lighting is a major concern to neighbours before a project is built.
(There are much cheaper visibility-based light dimming systems in development, but none that I know of have their FAA approval yet.)
posted by scruss at 7:46 AM on October 27, 2013 [3 favorites]
This thread is closed to new comments.
posted by Mario Speedwagon at 6:20 PM on October 26, 2013