Or so goes the argument whenever one of these damned Power Watches is called. Actually, it was this same discussion during #DarkNL that got me started digging into our local power system in some detail and spending far too much time on Twitter. Something about it seemed too easy and too foolish for words to be honest.
So, any truth to the claim?
Maybe. It depends on what time of the year you are talking about.
There's two problems with transmitting power to the Avalon in the existing, 2 line, system.
- High load on the Avalon drags the voltage down to the point that the system will collapse if it isn't propped up. This is what happened on the morning of March 4, 2015. I was asleep in a camp on the Snare River in the North West Territories and awoke by my vibrating phone. Twitter had exploded after the power went out.
- The lines over heat (thermally constrained) when the outdoor temperature gets up around 15 Celsius and load picks up on the Avalon. Think spring and fall of the year, not winter.
Item 2 dictates when the first unit at Holyrood gets started or stopped and item 1 dictates when the second and third units get started at Holyrood [1].
Now, let's toss in Vale's Long Harbour facility. In order to add that load to the system, it was necessary to relocate a capacitor bank from the newly decommissioned Long Harbour Terminal Station to Come By Chance Terminal Station. A good size cap bank was added, 153 MVAr versus 24 MVAr in the old one. MVAr, or reactive power is used to magnetize the power system. Without it, the active power, or MW, can't do any work like heating your house.
The installation of the Come By Chance capacitor bank provided extra MVAr to the Avalon 230 kV transmission system, propped up the voltage, and delayed the necessary start up of the second and third units at Holyrood as per item 1 above. This capacitor bank, installed in 2012, enabled the import of an extra 120 MW onto the Avalon thus saving fuel and improving efficiency at Holyrood [1, 2].
What this capacitor bank doesn't solve is item 2 above and item 2 is what dictates when the first Holyrood unit is started. For that you do need new transmission. In the spring and fall the new line would help delay the start up of the first Holyrood unit per item 2. That is a savings alright, no doubt, but it's not going to help us during the winter peaks. Unfortunately, there is no unused mystery capacity off the Avalon during peaks as the island is capacity constrained during these periods, i.e., we need new generation or smaller peaks. Also, starting and stopping Holyrood frequently is hard on the gear as the equipment is heated and cooled repeatedly. Thermal operators try to avoid that.
When the Grand Falls and Stephenville mills shut down there was some extra generation capacity and energy opened up as the power was no longer being used by the mills. That was 7 - 12 years ago. During peak times now we're using that extra power capacity as peak load has increased sufficiently to use it up. Doesn't help any that during the peaks we also end up losing a Holyrood unit or Hardwoods, etc.
What the devil does that all mean? The installation of the capacitor bank at Come By Chance TS enabled the import of some extra power onto the Avalon but now we've gotten to the point during peaks that there is no extra power left. Would a third line enable the import of extra power from off the Avalon? Yes it would, but during the peaks there isn't any. During the peaks the island is maxed out and running with low reserve power.
It's a bit different during the Spring to Fall. That's when the system is not in to the winter peak loads and so there would be some generation off the Avalon that the third line would help get to the major load centre on the Avalon. It has nothing to do with water spilling though, that would be base generation. So the third line would help during these periods as it would delay the start up of the first Holyrood unit and enable the import of some of that off Avalon energy.
I asked Hydro to provide spill data for the last 5 years and they were good enough to forward it to me, see the figure below. In the years 2011, 2012, 2013, and 2014 there was little to no spilling in the months of January, February, or March. As for this past year, Hydro hasn't spilled anything since the summer. That's the problem with trying to rely on spilled water, it isn't consistent, and our reservoirs are not large enough to store it all when it does happen.
Once the Maritime Link is built, the spilled energy, along with whatever else is available, is going to Nova Scotia and New England where it will be sold at market rates.
Hydro was going to build the third line back in 2012 but withdrew that application when the province decided it was going to go all in on Muskrat Falls. Back then the line was needed to get power in from a few small hydro plants that they would end up building instead of Muskrat Falls, and to improve upon items 1 and 2 above [5]. After sanction of Muskrat the reasons for the new line changed. I won't get into that here; read reference [4] if you're curious or need some material to help you sleep.
It's a bit different during the Spring to Fall. That's when the system is not in to the winter peak loads and so there would be some generation off the Avalon that the third line would help get to the major load centre on the Avalon. It has nothing to do with water spilling though, that would be base generation. So the third line would help during these periods as it would delay the start up of the first Holyrood unit and enable the import of some of that off Avalon energy.
I asked Hydro to provide spill data for the last 5 years and they were good enough to forward it to me, see the figure below. In the years 2011, 2012, 2013, and 2014 there was little to no spilling in the months of January, February, or March. As for this past year, Hydro hasn't spilled anything since the summer. That's the problem with trying to rely on spilled water, it isn't consistent, and our reservoirs are not large enough to store it all when it does happen.
 |
| NL Hydro 5 Year Spill Data |
Once the Maritime Link is built, the spilled energy, along with whatever else is available, is going to Nova Scotia and New England where it will be sold at market rates.
Hydro was going to build the third line back in 2012 but withdrew that application when the province decided it was going to go all in on Muskrat Falls. Back then the line was needed to get power in from a few small hydro plants that they would end up building instead of Muskrat Falls, and to improve upon items 1 and 2 above [5]. After sanction of Muskrat the reasons for the new line changed. I won't get into that here; read reference [4] if you're curious or need some material to help you sleep.
Would a third line from Bay D'Espoir to the Avalon help during the winter peaks? No.
Would a third line help reduce use of Holyrood in the Spring and Fall? Yes.
If you have any questions or comments leave them here or send me a message on Twitter, @kurtbsullivan. If you have some evidence to show otherwise, send it along.
References:
- Island Transmission System Outlook, System Planning Department, NL Hydro , December 2010, Pg 4 - 5., http://www.pub.nl.ca/applications/MuskratFalls2011/files/exhibits/Exhibit24-IslandTransmissionOutlook.pdf
- Squires, Erin. “Come By Chance Capacitor Bank” Email to Kurt Sullivan. February 10, 2016.
- Report on Island Interconnected System to Interconnection with Muskrat Falls addressing Newfoundland and Labrador Hydro, Liberty Consulting, December 17, 2014. (http://www.pub.nl.ca/applications/IslandInterconnectedSystem/files/reports/The-Liberty-Consulting-Group-Hydro-Report-12-17-2014.pdf)
- http://www.pub.nl.ca/applications/NLH2014Capital/NLHCBSUPP2014/TransmissionLine/application/Application-2014-04-30.pdf
- http://www.pub.nl.ca/applications/NLH2012Capital/files/application/NLH2012Application-VolumeII-Report10.pdf
- http://www.pub.nl.ca/applications/NLH2013GRA/files/rfi/PUB-NLH-016.pdf
- Newfoundland and Labrador Hydro 2013 Amended General Rate Application, Table 2.14, Section 2.5.1. http://www.pub.nl.ca/applications/NLH2013GRA-Amended/files/application/NLH-2013-GRA-Application-Volume-1-AMENDED-2014-11-10.pdf
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