Communications links

Last week there were a few unnecessary trips of the Ravenswood wind farm.  It drives home the importance of good telecommunications links.

Every time there is a trip, the wind farm goes off line.  It takes about 15 minutes for it to come back on line.  Not only do you lose production for those 15 minutes, but any time the wind farm trips off it is hard on the turbines.  Turbines like a stable electricity grid, and when the switch trips, the power to the turbines is interrupted.

The problem was with a communications line that runs from the Ravenswood substation to Hydro |One’s Forest Jura substation.  Ravenswood was sending a message that said we are OK, but Hydro One wasn’t receiving it.  So they sent a message to trip off the turbines. 

 

Hydro One has two approved standards of communication.  Ravenswood uses 4 wire leased lines from the telephone company, which in that area is People’s Telephone.  The other standard is a wireless connection, but Ravenswood has to communicate to Sarnia as well, and the distances are too great for wireless, so we use the phone company.

The 4 wire leased line system is ancient.  They don’t make modems for it anymore.  The telephone company cannot do any internal tests on it – they have to dispatch technicians to diagnose and fix it.  But it is a Hydro One approved standard, and so it has to be used.  My telecom engineer says that even the IP internet system is more reliable today.  It seems to me Hydro One should be looking at a newer standard.  \

People’s Telephone was very helpful, and arrived at the site the next day.  The found that the Ravenswood substation was sending 2800 Hz signals, but the Hydro One end was receiving only 2700 Hz.  All of the high frequencies were problematic.  They switched a circuit board in the system, and it seems to solve the problem.

I have heard of other generators who have had problems with the communications, with a negative impact on production.  It is a problem that needs better solutions.

 

I hope Hydro One will come up with a better standard in the future.

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