Rail Charging Converter system by Siemens

[John R]

Moderator note: Split from

MML Electrification: progress updates

There's an article about NR's plans in Rail this week (#765 p54). It seems that work on site will start in April 2015, the contractor being Carillion Powerlines. They will be using road-rail vehicles for the work, not a high-output system. The 125mph design isn't explicitly named but seems...

www.railforums.co.uk

There is an interesting article in the latest Modern Railways (I get a paper copy only, not the online subscription, so cannot link the article, apologies) that describes how Siemens has developed a way to significantly reduce the costs of providing power supply for electrified lines, and will also reduce the connection time substantially too.

I am not an electrical engineer, but as I understand it, instead of connecting to the 132kV supply and stepping down to 25kV, it connects to the local Distribution Network Supply (11kV?) and somehow stepping up to 25kV.

How are the contents of this structure (the Rail Charging Converter) set to transform the railway though? In simple terms, by making connections to the power grid for electrification quicker and much cheaper, and by enabling rapid charging of battery trains on the move, in addition to while stationary. The implications will be profound.

The article claims that it could also be used to enhance supply where there is currently electrification but insufficient supply for current and future demands. There's also an article about it here.

Siemens RCC: Rail Charging Revolution | The Edge | WeBid Consult

Explore Siemens Mobility's breakthrough Rail Charging Converter, transforming rail electrification with mobile innovation.

www.webidconsult.com

Rapid-charging solution to support greater electric train use

Innovative project tackles power supply issues and diesel replacement opportunities with battery charging technology to encourage transitions to electric trains.

www.ukri.org

The project was created to deliver a novel solution to this charging and power issue. It will enable simple installation of small, low-cost overhead line equipment (OLE) power supplies fed from existing standard local power supply cables, without affecting the power quality for the local area.

Crucially, the novel design of the product is compatible with all standard OLE-powered trains. It aims to accelerate and reduce the cost of decarbonisation of diesel passenger train routes across the UK. The solution also provides an opportunity to undertake safer, more efficient maintenance on tracks outside depots with the overhead line isolated, while the depot continues to prepare trains unaffected.

Power supply generated by the Rail Charging Converter (RCC) technology will be useful where the traditional electricity network has limitations...

Seems good news, although I'm conscious that moving to a position where new innovations are deployed on the railways seems to take years, so how quickly we will see any result from this remains to be seen.

 

[jfowkes]

There is an interesting article in the latest Modern Railways (I get a paper copy, so cannot link) that describes how Siemens has developed a way to significantly reduce the costs of providing power supply for electrified lines, and will also reduce the connection time substantially too. I am not an electrical engineer, but as I understand it, instead of connecting to the 132kV supply and stepping down to 25kV, it connects to the local Distribution Network Supply (11kV?) and somehow stepping up to 25kV.

The article claims that it could also be used to enhance supply where there is currently electrification but insufficient supply for current and future demands.

Seems good news, although I'm conscious that moving to a position where new innovations are deployed on the railways seems to take years, so how quickly we will see any result from this remains to be seen.

Was it referring to Static Frequency Converters (SFCs)?

There's a forum thread about them here and a Rail Engineer article here.

They are relatively new technology, but at the "available for use now" stage, not the " still years away from practical use" stage.

 

[Vexed]

instead of connecting to the 132kV supply and stepping down to 25kV, it connects to the local Distribution Network Supply (11kV?) and somehow stepping up to 25kV.

I would assume 33kV DNO (Distribution Network Operator) supply instead of 11kV. It would be rather high current if pulling from 11kV lines!

DNO connections are quicker so that is one aspect that's sped up.

 

[John R]

I would assume 33kV DNO (Distribution Network Operator) supply instead of 11kV. It would be rather high if pulling from 11kV lines!

DNO connections are quicker so that is one aspect that's sped up.

Thanks for the correction and clarification!

 

[Vexed]

Thanks for the correction and clarification!

And reading my reply again I've realised I missed the key word of high current! Edited now...

 

[John R]

Actually rereading the article it does say “by compliantly producing 25kV traction power for the overhead line from the lower voltage 11kV cables already running to most stations and depots.”

Was it referring to Static Frequency Converters (SFCs)?

There's a forum thread about them here and a Rail Engineer article here.

They are relatively new technology, but at the "available for use now" stage, not the " still years away from practical use" stage.

The article describes it as “similar to a a Static Frequency Converter” and seems to be a different company to the ones quoted in those articles, so not sure it’s exactly the same.

 

[GraphitProjekt]

Not sure if it's related, but there's a works compound popping up at Chesterfield, in the last few days safety signage for "SPL Powerlines" has gone up. I recall reading in this thread that there will be a substation not far south of here at Hasland, could they be doing survey work related to that? Apologies if it's completely unrelated!

do SPL powerlines also deliver Power & Distribution assets? I thought they just handled OLE. (My understanding is that there are three layers to electrification systems: all the Grid side stuff associated with the railway supply is the Traction Power System up to and including the xyz/25kV transformer, beyond the main transformer inside the substations is Power & Distribution this asset can be quite extensive on DC systems, and from where feeder wires attach to OLE masts is of course Overhead Line Equipment)

 

[sharpener]

I would assume 33kV DNO (Distribution Network Operator) supply instead of 11kV. It would be rather high current if pulling from 11kV lines!

Actually rereading the article it does say “by compliantly producing 25kV traction power for the overhead line from the lower voltage 11kV cables already running to most stations and depots.”

The article describes it as “similar to a a Static Frequency Converter” and seems to be a different company to the ones quoted in those articles, so not sure it’s exactly the same.

Having read the linked article on SFCs I would imagine what they are doing is taking power from all 3 phases of the 11kV supply and (via a DC link) inverting it into one 25kV feed.

This would draw the same phase current as a single phase supply from 33kV, and being balanced would for the DNO be much more acceptable as a load.

 

[jontyasaurus]

do SPL powerlines also deliver Power & Distribution assets? I thought they just handled OLE. (My understanding is that there are three layers to electrification systems: all the Grid side stuff associated with the railway supply is the Traction Power System up to and including the xyz/25kV transformer, beyond the main transformer inside the substations is Power & Distribution this asset can be quite extensive on DC systems, and from where feeder wires attach to OLE masts is of course Overhead Line Equipment)

I've no idea personally, but I'm sure more knowledgeable members will know.
I assumed that they would be most likely to be surveying things related to the substation/grid connection, as I don't want to get my hopes up about survey progress north of Derby!

 

[GraphitProjekt]

Having read the linked article on SFCs I would imagine what they are doing is taking power from all 3 phases of the 11kV supply and (via a DC link) inverting it into one 25kV feed.

I wonder if this is something only applicable to quite low power applications like depots for instance. Or maybe some kind of feeding model whereby each station has it's own substation (and station spacing is quite regular) - which is effectively the situation on the 750V DC world. Because 11kV lines are most often at the secondary distribution level (ie: they are fed by 33/11kV substations aka "Primary Substations") and so are fairly low power.

I don't know why they wouldn't just use the more high power 33kV network - you'd be sure to get a useful current because you're stepping down voltage not up. This would only work on 11kV lines if they were unusually well powered (like the ones in central London are that are powered directly at 132/11kV substations, but this isn't the norm by any means)

This would draw the same phase current as a single phase supply from 33kV, and being balanced would for the DNO be much more acceptable as a load.

You could also just use an SFC to draw from all 3 phases from a 33kV line. This is already in place on a small feeder station in Doncaster (powering just a depot I think). I didn't think there was any suggestion that SFCs on any supply (132 or 33) would use just a single phase - the whole point of them is that they don't do that. And for what it's worth, the phase to neutral voltage of a 33kV line is more like 19kV.

 

[GRALISTAIR]

I've no idea personally, but I'm sure more knowledgeable members will know.
I assumed that they would be most likely to be surveying things related to the substation/grid connection, as I don't want to get my hopes up about survey progress north of Derby!

I would still consider surveying for the Grid Connection/Feeder as progress. I can't help but get my hopes up as I am the eternal optimist by nature!

 

[sharpener]

I didn't think there was any suggestion that SFCs on any supply (132 or 33) would use just a single phase - the whole point of them is that they don't do that.

I think the distinction is more between a simple 33kV/25kV transformer feeder station which would not be balanced across the phases, and 11kV to 25kV via a SFC which would. And would give you better voltage control/matching hence avoiding the need for neutral sections.

Or maybe some kind of feeding model whereby each station has it's own substation (and station spacing is quite regular) - which is effectively the situation on the 750V DC world. Because 11kV lines are most often at the secondary distribution level (ie: they are fed by 33/11kV substations aka "Primary Substations") and so are fairly low power.

Yes and I think the other advantage is tapping comparatively low powers off the existing 11kV network would give much shorter lead times for new connections.

You could also just use an SFC to draw from all 3 phases from a 33kV line. This is already in place on a small feeder station in Doncaster (powering just a depot I think). ... And for what it's worth, the phase to neutral voltage of a 33kV line is more like 19kV.

I imagine the SFCs have an input transformer in either case to give a more reasonable DC link voltage. Phase to neutral voltage is immaterial as the neutral is not accessible anyway.

 

[GraphitProjekt]

I think the distinction is more between a simple 33kV/25kV transformer feeder station which would not be balanced across the phases, and 11kV to 25kV via a SFC which would. And would give you better voltage control/matching hence avoiding the need for neutral sections.

I'm pretty sure all single phase 25kV feeder stations are connected to 132kV or above networks, precisely because the disbalance would be too great for 33kV single phase. The only edge-cases I know of are for really short test track areas in depots like Selhurst and Ashford which run off the 33kV Network Rail system - but it's not like they can power more than one train, very slowly, probably only at night when the draw on the 33kV lines are low. I don't disagree that SFCs can allow way easier DNO connections for AC OLE - but there is basically no such thing as a single phase 33/25kV connection.

 

[sharpener]

I don't disagree that SFCs can allow way easier DNO connections for AC OLE - but there is basically no such thing as a single phase 33/25kV connection.

Wasn't sure. That would certainly explain why new connections are difficult to organise and have a long lead time.

 

[InTheEastMids]

I think the lower voltage connections via SFC people have been discussing will really come into their own on discontinuous schemes.

At 11kV, could have a 2-2.5 MVA connection at a branch line terminus to recharge things like 350s/755s. Matlock is the only place on the MML I can think of that might need something like this.

However, in these scenarios there are questions around whether to convert to 25kV and supply via a pantograph or directly with DC, and whether to use a lineside battery to reduce grid connection requirements (i.e. What GWR/Vivarail have done).

 

[stuving]

Siemens have been making and installing railway SFCs for years, now branded Sitras. And for more than two years they have also been promoting their RCC (rail charging converter) as suitable for en-route battery charging, but also for depots and minor lines; it's modular at 2.5 MW per module. One was ordered for Long Marston; is it in use yet?

So I wonder what, if anything, is new now? Here's some data sheets for the Sitras plus range and the RCC.

 

[InTheEastMids]

So I wonder what, if anything, is new now?

[Edit: Thanks for posting the links to the brochures.]
Not sure of the full answer, but I am looking in the direction of
- Batterification and discontinuous electrification -> new types of small schemes connecting at lower voltages

- Cost reductions of SFC technology along with
- Perhaps cost or delivery challenges with large single-phase connections as transmission is increasingly constrained and
- Higher demand from the railway (more electric trains with higher power demand per train)
-> economics skewing in favour of SFCs

Is it known whether the unbuilt supply points at Kegworth and Chesterfield will use SFC or traditional solutions?

 

[GraphitProjekt]

Weren't all the GSPs agreed in the pre-Grayling era when they would all be 400/50kV single phase for at AT system (275 in the case of Chesterfield)? I share this forum's optimism for SFCs in general but I don't think it'd be worth it to change the design of something that's already in delivery.

 

[GRALISTAIR]

There is an interesting article in the latest Modern Railways (I get a paper copy, so cannot link) that describes how Siemens has developed a way to significantly reduce the costs of providing power supply for electrified lines, and will also reduce the connection time substantially too. I am not an electrical engineer, but as I understand it, instead of connecting to the 132kV supply and stepping down to 25kV, it connects to the local Distribution Network Supply (11kV?) and somehow stepping up to 25kV.

The article claims that it could also be used to enhance supply where there is currently electrification but insufficient supply for current and future demands.

Seems good news, although I'm conscious that moving to a position where new innovations are deployed on the railways seems to take years, so how quickly we will see any result from this remains to be seen.

Yes the article you are referring to is I assume, the one on pages 58-61. They even show the Rail Charging Converter being trialled at Long Marston. Picture from Modern Railways article shown below.

 

[gingertom]

I think the lower voltage connections via SFC people have been discussing will really come into their own on discontinuous schemes. At 11kV, could have a 2-2.5 MVA connection at a branch line terminus to recharge things like 350s/755s. Matlock is the only place on the MML I can think of that might need something like this. However in these scenarios there's questions around whether to convert to 25kV and supply via a pantograph or directly with DC, and whether to use a lineside battery to reduce grid connection requirements (i.e. What GWR/Vivarail have done).

Back on topic about the Chesterfield/Hasland substation: There isn't a convenient 400 kV line crossing the railway to connect to as at Braybrooke.
Is the plan to connect at NG Chesterfield Substation and bring a 25 kV cable lineside at Hasland?

I would have thought they'd use a cable from the substation, but not 25kv. It's about a mile. If 400kv is available then a pair of transformers at the railway would make for a relatively simple ATF feeder station.

 

[Edvid]

I would have thought they'd use a cable from the substation, but not 25kv. It's about a mile. If 400kv is available then a pair of transformers at the railway would make for a relatively simple ATF feeder station.

Borehamwood / Long Meadow Farm connections are already stepped-down to 25kV within the respective National Grid 400kV compounds, and they're similarly lengthy.

 

[GRALISTAIR]

Borehamwood / Long Meadow Farm connections are already stepped-down to 25kV within the respective National Grid 400kV compounds, and they're similarly lengthy.

If you don't mind please, could you tell me in your opinion, what is lengthy in this sort of situation? 1 mile or The Great Extension Lead at Heyrod on the TPU.

 

[Old Rick]

Weren't all the GSPs agreed in the pre-Grayling era when they would all be 400/50kV single phase for at AT system (275 in the case of Chesterfield)? I share this forum's optimism for SFCs in general but I don't think it'd be worth it to change the design of something that's already in delivery.

At the rate we go in this country, not for the first time one set of events may impact another, seemingly, unrelated set.

If National Grid gets its way, there will not be any 275Kv in Chesterfield to attach to. NG are desperate to relieve the pressure on the Trent Valley from Keadby down to Ratcliffe, with 3 or 4 parallel overhead lines peeling 4 routes off down south, leaving 2 carrying on up the Trent to Willington, Drakelow and Rugeley. NG are getting a lot of flack about the Eastern Relief route from Grimsby to the Wash, but the Western Relief route is beginning to attract some.

NG intend to replace the 275Kv line from Brinsworth (Rotherham) to Chesterfield, and extend with new construction on to Willington with a 400Kv line, and either replacing or upgrading the existing route from Chesterfield to High Marnham to give a 400Kv cross-link.

A further complication is that I believe that the new Chesterfield sub-station is intended to be a replacement rather than an addition

 

[Edvid]

If you don't mind please, could you tell me in your opinion, what is lengthy in this sort of situation? 1 mile or The Great Extension Lead at Heyrod on the TPU.

I don't think one mile between a NG substation and feeder station is that lengthy. I recall reading upthread that it's easier to install a grid-side connection within an existing compound; must be why Long Meadow Farm doesn't tee off of the Sundon-Wymondley transmission lines.

 

[GraphitProjekt]

At the rate we go in this country, not for the first time one set of events may impact another, seemingly, unrelated set.

If National Grid gets its way, there will not be any 275Kv in Chesterfield to attach to. NG are desperate to relieve the pressure on the Trent Valley from Keadby down to Ratcliffe, with 3 or 4 parallel overhead lines peeling 4 routes off down south, leaving 2 carrying on up the Trent to Willington, Drakelow and Rugeley. NG are getting a lot of flack about the Eastern Relief route from Grimsby to the Wash, but the Western Relief route is beginning to attract some.

Everything NG want to do gets fierce opposition! They also want a new 400kV line from Norwich to Tilbury with a substation in the Colchester area, but it's seeing some very well organised Nimbyism in South Essex at least.

NG intend to replace the 275Kv line from Brinsworth (Rotherham) to Chesterfield, and extend with new construction on to Willington with a 400Kv line, and either replacing or upgrading the existing route from Chesterfield to High Marnham to give a 400Kv cross-link.

A further complication is that I believe that the new Chesterfield sub-station is intended to be a replacement rather than an addition

If I'm following correctly, is this the change?

If you don't mind please, could you tell me in your opinion, what is lengthy in this sort of situation? 1 mile or The Great Extension Lead at Heyrod on the TPU.

I would have thought they'd use a cable from the substation, but not 25kv. It's about a mile. If 400kv is available then a pair of transformers at the railway would make for a relatively simple ATF feeder station.

All of this pales in comparison to the use of feeder cables on GWML. St Brides (near Newport) to Canton (Cardiff) is 15km, Holly Cross ATFS (at Bramley 400kV) to Reading SATS is 17km, and Wootton Basset Jnc ATFS (w. of Swindon) to it's grid feed at Thingley Junction (near Chippenham) is 25km. All of these are apparently 3 cables at 25/0/-25kV

 

[GRALISTAIR]

All of this pales in comparison to the use of feeder cables on GWML. St Brides (near Newport) to Canton (Cardiff) is 15km, Holly Cross ATFS (at Bramley 400kV) to Reading SATS is 17km, and Wootton Basset Jnc ATFS (w. of Swindon) to it's grid feed at Thingley Junction (near Chippenham) is 25km. All of these are apparently 3 cables at 25/0/-25kV

Wow! They are long. Easier just to electrify - no?

 

[GraphitProjekt]

Wow! They are long. Easier just to electrify - no?

Quite!
Reading Independent Feeder, I'm pretty sure, explicitly exists because they didn't go ahead with Reading to Southampton.

Thingley Junction to Wootton Basset Junction is a funny one because it's already mostly wired up. I suppose for the most part, the point of it is to carry the 2cnd grid feed at Thingley up to be useful where the rest of the wires are. If they had electrified the line all the way through Bath and around up to Bristol perhaps they wouldn't have needed it because Thingley would be a node on a big ring. Also, it's worth noting that Thingley Jnc ATFS is some 5 or 6 miles away from the 400kV substation at Melksham - so it's actually even more than 25km in practice.

 

[John R]

Quite!
Reading Independent Feeder, I'm pretty sure, explicitly exists because they didn't go ahead with Reading to Southampton.

Thingley Junction to Wootton Basset Junction is a funny one because it's already mostly wired up. I suppose for the most part, the point of it is to carry the 2cnd grid feed at Thingley up to be useful where the rest of the wires are. If they had electrified the line all the way through Bath and around up to Bristol perhaps they wouldn't have needed it because Thingley would be a node on a big ring. Also, it's worth noting that Thingley Jnc ATFS is some 5 or 6 miles away from the 400kV substation at Melksham - so it's actually even more than 25km in practice.

I thought I read when the electrification was carried out that the reason for the Thingley to Wootton Basset extension lead is so that if the wires have to be switched off on the Chippenham line then the main line between Swindon and Bristol Parkway is unaffected

 

[Old Rick]

@ GraphitProjekt said; If I'm following correctly, is this the change?

I find it easier to follow Grid details on http://openinframap.org, but yes that is the schematic of the 2 projects on https://www.nationalgrid.com/electr...rk-and-infrastructure/infrastructure-projects, selecting East Midlands

edited for spelling error on first link

 

[swt_passenger]

I thought I read when the electrification was carried out that the reason for the Thingley to Wootton Basset extension lead is so that if the wires have to be switched off on the Chippenham line then the main line between Swindon and Bristol Parkway is unaffected

Yes, I’m sure there was a discussion in the main GW electrification thread way back, that confirmed that in the eventual full fit there would still be a parallel feeder alongside the track to Wooton Basset to allow the Chippenham line to be switched separately if required for maintenance or fault isolation. In other words when/if the running wires go up the existing feeder remains. Same set up eventually with Bramley I expect, in the unlikely scenario of OHLE to Basingstoke.