Dundee electrification plans

[Davester50]

I see there's additional drawings on the Dundee planning application dated 6th October 25 since the initial July uploads.

 

[GraphitProjekt]

Looking at the documents on the planning application, why is it 132/72.5kV for the traction connection? Is this for some big FSC to be supplied that higher voltage? What about the installation can we infer from this? (from this document)

 

[zwk500]

Looking at the documents on the planning application, why is it 132/72.5kV for the traction connection? Is this for some big FSC to be supplied that higher voltage? What about the installation can we infer from this? (from this document)

Links to planning portals are notoriously unstable, it's better to give the Planning Application reference, a link to the relevant authority's search page and the document name in the application.

 

[ChilliSauce]

The proposal may actually be for a Static Frequency Converter site .. Firstly it resolves the age old problem that AC electrified railways (bring single phase) cause an unbalance on the Grid 3 phase network (plus noise and harmonics back onto the Grid) and also neutral sections can be dispensed with. If this was a serious design it would be with Auto Transformer Feeders and aerial earths

 

[GraphitProjekt]

Links to planning portals are notoriously unstable, it's better to give the Planning Application reference, a link to the relevant authority's search page and the document name in the application.

I see;
25/00359/FULN on Dundee City Council, but also this slightly quicker link still works for me some days later. I was probably looking at drawing 16 but the thing I was interested in is in the title of all the drawings.

The proposal may actually be for a Static Frequency Converter site .. Firstly it resolves the age old problem that AC electrified railways (bring single phase) cause an unbalance on the Grid 3 phase network (plus noise and harmonics back onto the Grid) and also neutral sections can be dispensed with. If this was a serious design it would be with Auto Transformer Feeders and aerial earths

Yeah I was assuming anything being planned in these days would be SFC. But why would they want to give it such a high voltage outright. From the PWI video on Potteric Carr, it seems you have a step-down transformer from the supplier, then the power electronics component, then a second transformer presumably outputting 25kV to the railside FS. So theoretically the SFC could operate at a different voltage, but why it happens that way is something I'd want to know more about.

 

[stuving]

Looking at the documents on the planning application, why is it 132/72.5kV for the traction connection? Is this for some big FSC to be supplied that higher voltage? What about the installation can we infer from this? (from this document)

It's a typo for 132/27.5. Someone has got the idea that they should use the off-load voltage, though it's not how the nominal voltage is usually given. The planning statement says there are two 132/25 kV transformers there.

 

[ChilliSauce]

I see;
25/00359/FULN on Dundee City Council, but also this slightly quicker link still works for me some days later. I was probably looking at drawing 16 but the thing I was interested in is in the title of all the drawings.


Yeah I was assuming anything being planned in these days would be SFC. But why would they want to give it such a high voltage outright. From the PWI video on Potteric Carr, it seems you have a step-down transformer from the supplier, then the power electronics component, then a second transformer presumably outputting 25kV to the railside FS. So theoretically the SFC could operate at a different voltage, but why it happens that way is something I'd want to know more about.

I suspect this is just a generic application . But this could very well be a 3 phase supply feed then with a delta transformer and 3 full wave rectifiers . Plus a Star transformer to get a derived neutral and another 3 full wave rectifiers so giving a "12 pulse" DC supply into the Static Frequency Converter.

 

[GraphitProjekt]

I suspect this is just a generic application . But this could very well be a 3 phase supply feed then with a delta transformer and 3 full wave rectifiers . Plus a Star transformer to get a derived neutral and another 3 full wave rectifiers so giving a "12 pulse" DC supply into the Static Frequency Converter.

Not sure I entirely follow, are you saying the primary supply is split across two transformers one of which is delta the other star and then both getting rectified??

Also, on the Potteric Carr video all the illustrations were like this

I get that the first transformer is (in this case) 33/25kV, but what's the one on the other side for? Purely isolation? Why do they need isolation?

 

[stuving]

Not sure I entirely follow, are you saying the primary supply is split across two transformers one of which is delta the other star and then both getting rectified??

Also, on the Potteric Carr video all the illustrations were like this
View attachment 192744
I get that the first transformer is (in this case) 33/25kV, but what's the one on the other side for? Purely isolation? Why do they need isolation?

The voltage has to be stepped up to 25 kV at the output. IGBTs don't like voltages anywhere near 25 kV, and I don't think anyone has found it makes sense to stack enough modules in series to reach that level. For one thing, to share the voltage equally between stacked modules calls for a parallel resistor chain. And that wastes power and reduces efficiency.

 

[GraphitProjekt]

Good to know thanks, what kind of voltage do you think a traction SFC would be operating at in those situations

 

[HSTEd]

The voltage has to be stepped up to 25 kV at the output. IGBTs don't like voltages anywhere near 25 kV, and I don't think anyone has found it makes sense to stack enough modules in series to reach that level. For one thing, to share the voltage equally between stacked modules calls for a parallel resistor chain. And that wastes power and reduces efficiency.

The galvanic isolation on the traction side can also prevent annoyances like the converters driving DC current into the traction supply, which can happen under certain circumstances with these systems.

 

[stuving]

The galvanic isolation on the traction side can also prevent annoyances like the converters driving DC current into the traction supply, which can happen under certain circumstances with these systems.

I was going to add "and earthing". But earthing of power systems is black art as far as I'm concerned, and grid earthing even more arcane.

 

[ChilliSauce]

Not sure I entirely follow, are you saying the primary supply is split across two transformers one of which is delta the other star and then both getting rectified??

Also, on the Potteric Carr video all the illustrations were like this
View attachment 192744
I get that the first transformer is (in this case) 33/25kV, but what's the one on the other side for? Purely isolation? Why do they need isolation?

I suggest you Google "12 Pulse DC converter" or "12 pulse DC rectifier" you should get loads of stuff that explains how it works and it's advantages.

 

[hwl]

Not sure I entirely follow, are you saying the primary supply is split across two transformers one of which is delta the other star and then both getting rectified??

Yes - he is describing exactly what NR, LU and many other globally do to create "DC" traction power supply. It is best described as DC -ish and as ruff as the North Sea in a force 10 gale. The Star-Delta combination gives you an angular offset between the peaks (as well as an amplitude difference) hence instead of 3 phase producing 6 pulses though either star or delta you get an asymmetric 12 pulse that goes into the 3rd/4th rails /DC OHLE.

Image from a quick google (most aren't applicable to rail)

== Doublepost prevention - post automatically merged: 23 Nov 2025 ==

I suggest you Google "12 Pulse DC converter" or "12 pulse DC rectifier" you should get loads of stuff that explains how it works and it's advantages.

Much of which is of dubious quality having just had a look!

 

[zwk500]

I see;
25/00359/FULN on Dundee City Council, but also this slightly quicker link still works for me some days later. I was probably looking at drawing 16 but the thing I was interested in is in the title of all the drawings.

Thanks, the link to the application works, but for some reason the direct link to the document didn't!

 

[ChilliSauce]

Yes - he is describing exactly what NR, LU and many other globally do to create "DC" traction power supply. It is best described as DC -ish and as ruff as the North Sea in a force 10 gale. The Star-Delta combination gives you an angular offset between the peaks (as well as an amplitude difference) hence instead of 3 phase producing 6 pulses though either star or delta you get an asymmetric 12 pulse that goes into the 3rd/4th rails /DC OHLE.

Image from a quick google (most aren't applicable to rail)

== Doublepost prevention - post automatically merged: 23 Nov 2025 ==


Much of which is of dubious quality having just had a look!

Yes so most of the noise generated by a 12 pulse DC electrification system will be at 600Hz Unlike 25kV electrification where you have to have noise immunity from 50Hz

 

[59CosG95]

Worth mentioning on here that SFCs (Static Frequency Converters) and AT (autotransformer) feeding aren't mutually exclusive by design, as this post from LinkedIn about Rail Baltica shows:

#sfc #matters #trade #reshape #marter #greener #reliable #railbaltica #highspeedrail #electrification #railengineering #railinfrastructure #sfc | Álvaro López Pedrosa

Rail Baltica’s Electrification Innovation: SFC Traction Substations at Scale Rail Baltica’s €1.77bn electrification contract (signed September 2025 by COBELEC Rail Baltica—JV of Cobra and Elecnor) delivers a standard 2x25 kV 50 Hz catenary along its 870 km corridor—common for high-speed lines...

www.linkedin.com

(I've copied this on the phone so I can't copy the full text unfortunately)

 

[QueensCurve]

It is encouraging that they have put the planning application in. Hopefully the proposed start date of June 2026 doesn't turn out to be too optimistic and that this actually gets through planning without too much hassle.

As an alumnus of The University of Dundee I hope I live long enough to see it completed.

== Doublepost prevention - post automatically merged: 23 Nov 2025 ==

I'd imagine the Invergowrie feeder station, if still happening, would only power the line between Perth and Dundee. Whereas the Stannergate feeder station will power Dundee and north.

Where would the neutral sections be? Dundee station and Dock St Tunnel are below mean sea level with steep gradients either side.

 

[ChilliSauce]

As an alumnus of The University of Dundee I hope I live long enough to see it completed.

== Doublepost prevention - post automatically merged: 23 Nov 2025 ==


Where would the neutral sections be? Dundee station and Dock St Tunnel are below mean sea level with steep gradients either side.

If SFC technology is adopted you don't have a neutral section as such but a switched overlap with the switch normally closed

 

[stuving]

The SFC descriptions I have are not very recent, so I've been looking for newer ones. But in fact this from Siemens dated 2018 already suggests the output transformer may be optional. In three separate places, it says:

Due to the multilevel technology no traction transformer is needed to feed the overhead contact line.

Traction transformer / Output reactor
A simple traction transformer with a primary and secondary winding is used for feeding a high-voltage network of the railway.

Traction transformer If traction power is to be supplied directly into the contact line, a traction transformer will not be needed because of the high output voltages of the multilevel converter. The converter is then decoupled from the traction power supply network by means of an output reactor.

However, it does not say whether this applies at 25 kV 50 Hz, or only at 15 kV 16.7 Hz (which was their original and major market). I imagine the gains and drawbacks would be different for those two cases. Plus, of course, a transformer may be needed for other reasons.

None of this applies to Dundee Stannergate, though, as it will not use SFCs. See this from SSEN-T in March 2025. The Planning Statement was more recent (May) but access requires wrestling with Dundee's planning portal, which has gone into another sulk.

Stannergate 132kV GIS substation

To facilitate Network Rail’s connection requirement and replace the existing assets at Dudhope
GSP, the following equipment will be installed at the Stannergate 132kV GIS substation:
• An overall site to be developed of approximately 5.25 hectares to accommodate all
required equipment
• 132kV indoor GIS substation building housing the 132kV double busbar configuration
• Two 132/25kV 25MVA rail transformers housed in buildings
• Two 132/33kV 120MVA grid transformers housed in buildings
• 33kV distribution building.
• 132kV underground cable to connect Stannergate substation to the existing 132kV
transmission network in Dundee.

Work done by others:
• Underground cable connection between Network Rail Feeder Station and the rail (route tbc)
• Underground cable connection between 33kV Building and Dudhope (route tbc).

 

[GraphitProjekt]

None of this applies to Dundee Stannergate, though, as it will not use SFCs. See this from SSEN-T in March 2025. The Planning Statement was more recent (May) but access requires wrestling with Dundee's planning portal, which has gone into another sulk.

I saw this too and elsewhere it says the firm supply capacity is is 16.2MVA from 25MVA transformers which comparable to traditional 132kV feeding. The 2 SFCs in operation have much higher rated capacities and FSC.

With all that being said, I returned to the old PWI video on Hambleton Junction SFC from of the Eastern Region traction power team, they included this schematic which does seem to suggest the the SFC is run at 25kV and the final transformer is 1:1.


In a different talk the same guy uses the same slide and says the final transformer was for UK compliance purposes (so isolation i guess) and otherwise "we could have used a reactor". (All those youtube links are timestamped; you don't have to wade through anything although both videos are very interesting in their own rights)

 

[QueensCurve]

You can see the site on Google maps. The foundations are there.

Which precise location is it? https://www.google.com/maps/place/M...try=ttu&g_ep=EgoyMDI1MTExNy4wIKXMDSoASAFQAw==

 

[zwk500]

Which precise location is it? https://www.google.com/maps/place/Marshall+Meadows+Manor+House+Hotel/@55.801537,-2.046634,2309m/data=!3m1!1e3!4m9!3m8!1s0x488747c148e0883b:0xcada12fabe7c7ca2!5m2!4m1!1i2!8m2!3d55.802884!4d-2.0344361!16s/m/0gx_8sv?hl=en&entry=ttu&g_ep=EgoyMDI1MTExNy4wIKXMDSoASAFQAw==

One imagines here: https://maps.app.goo.gl/28Vc7VNLi68NCqGj7

Image snipped in case people have slightly different variations of aerial imagery.

 

[QueensCurve]

One imagines here: https://maps.app.goo.gl/28Vc7VNLi68NCqGj7

Image snipped in case people have slightly different variations of aerial imagery.
View attachment 192782

Thank you.

 

[Morayshire]

The Dundee Courier is reporting that a building warrant application has been made to demolish the existing tanks on the Stannergate site

Plans to demolish former tank site next to Dundee’s Eden Project to make way for substation

A huge former oil refinery site near land set aside for Dundee’s Eden Project is set to be demolished.

A building warrant has been submitted to clear an 8.9-acre stretch of land to the north of East Dock Street in the Stannergate area.

The site is just yards from where the £130 million Eden Project will be built.

However, it has been earmarked for a SSEN 132kV substation and a 132kV Network Rail feeder station.

The new site would stretch around 350 metres along the A92 and would include an 18-metre tall control building.

In July 2025 The Courier reported how construction could begin in June and SSEN aims to connect the substation to the network in October 2027.

Two redundant warehouses and eight oil storage tanks, which haven’t been used for at least 12 years, are currently located on the land.

The warrant explains how clearing the site would involve knocking down these structures.

Bund walls and concrete hardstandings would also be demolished.

Previously the land was put up for sale in summer 2024; however, it has not been occupied since.

SSEN has proposed the substation as a replacement for the Dudhope substation on Bell Street, which has been in operation for nearly 60 years.

The feeder station would be part of the electrification of the railway line between Dundee and Montrose.

This is part of the Scottish Government’s £120 million plans to electrify Scotland’s rail network by 2035.

There is not enough capacity at the Dudhope site to include the Network Rail connection, which must be within two kilometres of the line.

Swedish oil and bitumen manufacturer Nynas is the current owner of the land.

The company operates a refinery nearby on East Camperdown Street.

Nynas UK said it was not in a position to comment as negotiations are ongoing for the future use of the land.

Planning permission for Dundee’s Eden Project was granted in summer 2024.

However, its development still depends on securing tens of millions in funding.

No major work has taken place on the site yet.

The full planning application for the substation and feeder station is available on the Dundee City Council website.

 

[Davester50]

There's been a lot of trees cut back near the A85 flyover along Riverside in the last few weeks.

 

[QueensCurve]

A quick play at Google maps suggests the old oil store is about a mile east of the station-Manningtree, Oxenholme, Penrith & Carlisle all have similarly awkward neutral sections from memory.

It is a very steep gradient out of Dock St Tunnel. A neutral section would presumably not be acceptable there.

 

[najaB]

It is a very steep gradient out of Dock St Tunnel. A neutral section would presumably not be acceptable there.

That's true, however the existing tank farm is over 400m from the top of the tunnel incline, so I'd think it would be fine.

 

[zwk500]

It is a very steep gradient out of Dock St Tunnel. A neutral section would presumably not be acceptable there.

The site appears to be approximately here: https://maps.app.goo.gl/ewKfV2ELoJkbfcRW9 and it looks like there's a reasonable stretch of easy gradient where a Neutral section could be located.

The bridge with the Oil pipes is on a section of 1 in 3060 according to the 5 Miles.

 

[najaB]

The site appears to be approximately here: https://maps.app.goo.gl/ewKfV2ELoJkbfcRW9 and it looks like there's a reasonable stretch of easy gradient where a Neutral section could be located.

The bridge with the Oil pipes is on a section of 1 in 3060 according to the 5 Miles.

Also, there's no reason that the neutral section has to be immediately adjacent to the grid feeder station.