National Grid electricity transmission lines or Feeder station?

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aspire_13

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I am designing a solar farm as my dissertation that would provide electricity to power trains. However, I am not connecting the solar farm straight to the overhead line, but the grid... but I have a couple of questions.

What exactly should I connect my solar farm with? National Grid electricity transmission lines used by National Rail or the Feeder station?

Thank you
 
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Bald Rick

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Neither. You would connect it to the local Distribution Network Operator’s system.

If you had your panels near to a D.C. electrified railway line, it would make more sense to connect straight into the railways high voltage network (which runs alongside D.C. electrified lines). But someone has already thought of that - google Riding Sunbeams.
 

GRALISTAIR

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I am designing a solar farm as my dissertation that would provide electricity to power trains. However, I am not connecting the solar farm straight to the overhead line, but the grid... but I have a couple of questions.

What exactly should I connect my solar farm with? National Grid electricity transmission lines used by National Rail or the Feeder station?

Thank you
Of course solar produces DC so you would need inverters etc. Sorry if that sounds like I am trying to teach my grand mother to suck eggs.
 
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Nicholas Lewis

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Neither. You would connect it to the local Distribution Network Operator’s system.

If you had your panels near to a D.C. electrified railway line, it would make more sense to connect straight into the railways high voltage network (which runs alongside D.C. electrified lines). But someone has already thought of that - google Riding Sunbeams.
Be expensive to connect to NR's high voltage network as most of it is 33kV so you would need a transformer to step up the voltage after you've inverted back to AC. As Bald Rick says it would make far more sense to connect at DSO level as best to look at this from a holistic point of view as the more embedded solar you have this offsets carbon generation. Connecting at 25kV is even more problematic as traction demand is very lumpy but solar power is constant (whilst the sun is out) so you run the disk of having to disconnect it if there's no trains within a feeding section.
 

Bald Rick

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Be expensive to connect to NR's high voltage network as most of it is 33kV so you would need a transformer to step up the voltage after you've inverted back to AC. As Bald Rick says it would make far more sense to connect at DSO level as best to look at this from a holistic point of view as the more embedded solar you have this offsets carbon generation. Connecting at 25kV is even more problematic as traction demand is very lumpy but solar power is constant (whilst the sun is out) so you run the disk of having to disconnect it if there's no trains within a feeding section.

Riding Sunbeams originally thought they would be going direct into the 750 D.C., but worked out it was better to go into the 33kV (with inverters) as it was much more likely there would be a load. In fact I think the load they cover is basically the resistance losses. Still, worth having for next to nothing I suppose.
 

Dai Corner

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Don't worry about the physical connection, just get your solar farm connected to the DNO as suggested above and sign a deal with a railway infrastructure company to buy ' your' electricity. The paper is more important than the copper or the electrons in todays's market. Think of it as generators pouring electricity into a big pool and distributors (or large users) taking out what they need and the two groups agreeing prices between each other.

Unfortunately Network Rail already have a deal with EDF to supply them with their nuclear-generated electricity but Transport for Wales will be buying renewable for their Cardiff Valleys lines once they're electrified in a few years time.

I suppose the kind of answers your tutor will be looking for will depend on what you're studying though. An engineering student, a business student and a climate science student would all look at it differently.
 
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aspire_13

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Be expensive to connect to NR's high voltage network as most of it is 33kV so you would need a transformer to step up the voltage after you've inverted back to AC. As Bald Rick says it would make far more sense to connect at DSO level as best to look at this from a holistic point of view as the more embedded solar you have this offsets carbon generation. Connecting at 25kV is even more problematic as traction demand is very lumpy but solar power is constant (whilst the sun is out) so you run the disk of having to disconnect it if there's no trains within a feeding section.
So you suggest connecting to a transformer? The thing is the land I am developing the solar farm at belongs to Network Rail and is in Cardiff Central Station, so my question is: Can I not connect straight to the feeders that are present along the rail?

Don't worry about the physical connection, just get your solar farm connected to the DNO as suggested above and sign a deal with a railway infrastructure company to buy ' your' electricity. The paper is more important than the copper or the electrons in todays's market. Think of it as generators pouring electricity into a big pool and distributors (or large users) taking out what they need and the two groups agreeing prices between each other.

Unfortunately Network Rail already have a deal with EDF to supply them with their nuclear-generated electricity but Transport for Wales will be buying renewable for their Cardiff Valleys lines once they're electrified in a few years time.

I suppose the kind of answers your tutor will be looking for will depend on what you're studying though. An engineering student, a business student and a climate science student would all look at it differently.
Unfortunately I can not do that because the land where I have developed the solar farm belongs to Network Rail, so it will have to be connecting the solar farm to a feeder or something like that
 

swt_passenger

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So you suggest connecting to a transformer? The thing is the land I am developing the solar farm at belongs to Network Rail and is in Cardiff Central Station, so my question is: Can I not connect straight to the feeders that are present along the rail?


Unfortunately I can not do that because the land where I have developed the solar farm belongs to Network Rail, so it will have to be connecting the solar farm to a feeder or something like that
What do you understand by a ‘feeder’ that is ‘present along the rail’ in this context, noting your unanswered question in another thread here:
 

aspire_13

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Neither. You would connect it to the local Distribution Network Operator’s system.

If you had your panels near to a D.C. electrified railway line, it would make more sense to connect straight into the railways high voltage network (which runs alongside D.C. electrified lines). But someone has already thought of that - google Riding Sunbeams.
rtru.png

So from this picture, where exactly should I connect my solar farm considering it belongs to Network Rail?
 

zwk500

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So from this picture, where exactly should I connect my solar farm considering it belongs to Network Rail?
When you say you're doing this for a dissertation does this level of advice breach the academic integrity standards for your course/Degree? I'm not trying to be mean or block you, I just wouldn't want your assessors to mark you down because the work wasn't your own. No-one on here knows the criteria your project is marked against, so only you (and your assessors, who may not see this, but then again they might) know the answer to that.
 

swt_passenger

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View attachment 94799

So from this picture, where exactly should I connect my solar farm considering it belongs to Network Rail?
Nearly everything in that picture is trackside about 8 or 9 miles east of Cardiff station. That’s where the traction 25kV-0-25kV supply feeds in, but that’s also where the control and protection is, so you wouldn’t be able to connect into it in Cardiff Central as far as I’m aware.
 

aspire_13

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When you say you're doing this for a dissertation does this level of advice breach the academic integrity standards for your course/Degree? I'm not trying to be mean or block you, I just wouldn't want your assessors to mark you down because the work wasn't your own. No-one on here knows the criteria your project is marked against, so only you (and your assessors, who may not see this, but then again they might) know the answer to that.
No one on here is doing my dissertation, I have done all my work but I have doubts about something and I am doing research and asking questions, not like I have copied and pasted it from somewhere, I am trying to understand it.
 

zwk500

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No one on here is doing my dissertation, I have done all my work but I have doubts about something and I am doing research and asking questions, not like I have copied and pasted it from somewhere, I am trying to understand it.
Fair enough, then in that case I'd say:
So from this picture, where exactly should I connect my solar farm considering it belongs to Network Rail?
The solar farm would connect in at the substation/control room. As swt_passenger has said, this is some way from Cardiff Central.
 

hwl

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No one on here is doing my dissertation, I have done all my work but I have doubts about something and I am doing research and asking questions, not like I have copied and pasted it from somewhere, I am trying to understand it.
You are right to have your doubts!!!

Virtually all solar farms (and many land based wind farms) feed into DNO (Distribution Network Operator) networks not the grid (hence not in the diagram below). The threshold between DNO and transmission grid is 132kV or less for DNO and higher for Nat Grid which in practice means (275/400kV).

3rd rail (nominally 750V DC) is fed from local NR substations (including rectification using NR 33/11KV 3 Phase AC network along the track side. This is fed from mix of Nat Grid or DNO connections between 11kV to 400kV. The transformer and rectifier in each substation draws equally from all 3phases. 3rd rail is much more amenable to solar top up than OHLE but even riding sunbeams found this much more difficult than expected.

OHLE (nominally 25kv AC) is fed from two of the 3 phases of the DNO or Nat Grid (132-400kV) with either 25kV/0V or +/-25kV with local autotransformer to provide a more stable 25kV local and minimise losses.

Most electric trains also have regenerative braking to the returned energy used locally by trains or in the OHLE case potentially returned to DNO /Grid which is not that compatible with solar.

A typical train in the area under full load can take just over 3MW.

Realistically the solar farm would be powering the station lights or powering the signalling system (600V) as others have done.

As others have said the local feeder (+/-25kV in this case making it even harder) is on the north side of the tracks north of the village of St Brides / south of Imperial Park


View attachment 94799

So from this picture, where exactly should I connect my solar farm considering it belongs to Network Rail?
 
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aspire_13

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Fair enough, then in that case I'd say:

The solar farm would connect in at the substation/control room. As swt_passenger has said, this is some way from Cardiff Central.

You are right to have your doubts!!!

Virtually all solar farms (and many land based wind farms) feed into DNO (Distribution Network Operator) networks not the grid (hence not in the diagram below). The threshold between DNO and transmission grid is 132kV or less for DNO and higher for Nat Grid which in practice means (275/400kV).

3rd rail (nominally 750V DC) is fed from local NR substations (including rectification using NR 33/11KV 3 Phase AC network along the track side. This is fed from mix of Nat Grid or DNO connections between 11kV to 400kV. The transformer and rectifier in each substation draws equally from all 3phases. 3rd rail is much more amenable to solar top up than OHLE but even riding sunbeams found this much more difficult than expected.

OHLE (nominally 25kv AC) is fed from two of the 3 phases of the DNO or Nat Grid (132-400kV) with either 25kV/0V or +/-25kV with local autotransformer to provide a more stable 25kV local and minimise losses.

Most electric trains also have regenerative braking to the returned energy used locally by trains or in the OHLE case potentially returned to DNO /Grid which is not that compatible with solar.

A typical train in the area under full load can take just over 3MW.

Realistically the solar farm would be powering the station lights or powering the signalling system (600V) as others have done.

As others have said the local feeder (+/-25kV in this case making it even harder) is on the north side of the tracks north of the village of St Brides / south of Imperial Park

You are right to have your doubts!!!

Virtually all solar farms (and many land based wind farms) feed into DNO (Distribution Network Operator) networks not the grid (hence not in the diagram below). The threshold between DNO and transmission grid is 132kV or less for DNO and higher for Nat Grid which in practice means (275/400kV).

3rd rail (nominally 750V DC) is fed from local NR substations (including rectification using NR 33/11KV 3 Phase AC network along the track side. This is fed from mix of Nat Grid or DNO connections between 11kV to 400kV. The transformer and rectifier in each substation draws equally from all 3phases. 3rd rail is much more amenable to solar top up than OHLE but even riding sunbeams found this much more difficult than expected.

OHLE (nominally 25kv AC) is fed from two of the 3 phases of the DNO or Nat Grid (132-400kV) with either 25kV/0V or +/-25kV with local autotransformer to provide a more stable 25kV local and minimise losses.

Most electric trains also have regenerative braking to the returned energy used locally by trains or in the OHLE case potentially returned to DNO /Grid which is not that compatible with solar.

A typical train in the area under full load can take just over 3MW.

Realistically the solar farm would be powering the station lights or powering the signalling system (600V) as others have done.

As others have said the local feeder (+/-25kV in this case making it even harder) is on the north side of the tracks north of the village of St Brides / south of Imperial Park
I think I am going to change the dissertation a bit and as you said, power the train station as well as the signalling system as I am finding it really difficult to connect the solar farm to the electrified system and it is the only thing I have left to finish my dissertation. When you say the signalling system (600V) what do you mean?
 

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You would have difficulty connecting to the OHL system, as the electrical control room has to have full control of which OHL sections are live and which are isolated. Both for emergencies, incidents and for planned engineering work.

Large PV Solar installations are normally connected to the DNO network for two reasons. First it saves the expense of the higher voltage transformers and switch gear. And secondly, there is normally at least a minimum load connected to the DNO network.

Small scale PV Solar installations are connected to the single phase line and neutral that are supplied to a property, or to the three phase supply to an industrial building.

Remember, with an AC network, the frequency of each and every power source has to be carefully controlled, as well as the voltage output.

With PV solar connecting as described above, the existing national network control systems can control the power stations on the network as normal, as the power from the PV Solar installations effectively just looks like a reduced load on the national network.
 

hwl

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I think I am going to change the dissertation a bit and as you said, power the train station as well as the signalling system as I am finding it really difficult to connect the solar farm to the electrified system and it is the only thing I have left to finish my dissertation. When you say the signalling system (600V) what do you mean?
The (local) signalling system power supply including the signals, train detection systems point motors, rail heating for the point in cold weather. This is usually fed from local DNO supplies and is 650V AC.

A good intro here:

Edit to add also worth a look at Garry Keenor's excellent railway electrification guide, the pdf can be downloaded here:
 
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Annetts key

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The (local) signalling system power supply including the signals, train detection systems point motors, rail heating for the point in cold weather. This is usually fed from local DNO supplies and is 650V AC.

A good intro here:
The signalling system uses a single phase 650V AC network that runs along the track side. It’s fed from a suitable DNO feed that has no other customers on it (guaranteed supply) and then feeds to a generator/switch room. The generator automatically starts up and takes over the load in the event of a loss of ‘mains’ supply. Optionally, the 650V AC supply from this then feeds to a large 650V UPS so that there is no loss of supply during the time that the generator takes to run up to speed and produce it’s output. The larger installations are rated in the order of 100kVA.

This 650V AC network supplies ALL the power required by the signalling system. Including for lineside colour light signals, point machines/point operating equipment, track circuits/axle counter equipment (train detection), and all the required circuitry and control equipment.

The supply for the electric point/switch rail heating is normally a convenient non-guaranteed 400V three-phase supply from a DNO. For smaller installations, it may be a 230V single phase supply. Only at very important junctions would you find a back-up generator. These systems are provided to prevent the points/switch rails from icing up or becoming overwhelmed with snow during winter weather.
 

aspire_13

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The signalling system uses a single phase 650V AC network that runs along the track side. It’s fed from a suitable DNO feed that has no other customers on it (guaranteed supply) and then feeds to a generator/switch room. The generator automatically starts up and takes over the load in the event of a loss of ‘mains’ supply. Optionally, the 650V AC supply from this then feeds to a large 650V UPS so that there is no loss of supply during the time that the generator takes to run up to speed and produce it’s output. The larger installations are rated in the order of 100kVA.

This 650V AC network supplies ALL the power required by the signalling system. Including for lineside colour light signals, point machines/point operating equipment, track circuits/axle counter equipment (train detection), and all the required circuitry and control equipment.

The supply for the electric point/switch rail heating is normally a convenient non-guaranteed 400V three-phase supply from a DNO. For smaller installations, it may be a 230V single phase supply. Only at very important junctions would you find a back-up generator. These systems are provided to prevent the points/switch rails from icing up or becoming overwhelmed with snow during winter weather.

Perfect, I kind of have an idea of what I have to change and leave like it is in my project. If someone has a paper on how electricity consumption from signaling is calculated or assumed, feel free to post it on here. Thank you very much for your help, I like doing this project as it is making me learn a lot about something I knew nothing about. Also, due to COVID 19 students have had it a bit difficult to collect data and research and asking is a so important at the moment.
 

Bald Rick

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Depending on the scale of your Solar installation, I would have it feeding Cardiff station rather than the signalling power supply. Firstly, the signalling power supply requires a much higher level of reliability and redundancy, hence why it almost always has at least two sources and usually three, all of which can supply 24/7. Solar would put another feed in, and another point of failure, for a variable supply that will generate at perhaps an average of 11% of its rated capacity over the course of a year.

The station power needs less security, and is also in one place (and the right place). London Blackfriars has a 1MW solar installation on the roof, and that supplies about half the station power needs over the course of the year. (That does include 4 lifts and 4 escalators though).
 

aspire_13

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Depending on the scale of your Solar installation, I would have it feeding Cardiff station rather than the signalling power supply. Firstly, the signalling power supply requires a much higher level of reliability and redundancy, hence why it almost always has at least two sources and usually three, all of which can supply 24/7. Solar would put another feed in, and another point of failure, for a variable supply that will generate at perhaps an average of 11% of its rated capacity over the course of a year.

The station power needs less security, and is also in one place (and the right place). London Blackfriars has a 1MW solar installation on the roof, and that supplies about half the station power needs over the course of the year. (That does include 4 lifts and 4 escalators though).

This is what I am doing at the minute. I have had the project ready for a few weeks but something did not seem quite right to me so I am changing it to supply power to the train station instead. However, when it comes to energy consumption at the train station I can think of: electricity, lifts, heating and cooling, and not a lot more. Does any of you have any idea of what else can consume energy at a train station?
 

Dai Corner

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This is what I am doing at the minute. I have had the project ready for a few weeks but something did not seem quite right to me so I am changing it to supply power to the train station instead. However, when it comes to energy consumption at the train station I can think of: electricity, lifts, heating and cooling, and not a lot more. Does any of you have any idea of what else can consume energy at a train station?

Ticket machines, ticket gates, information and advertising displays, public address systems, catering outlets (refrigeration, cooking,hot drink making), cleaning machinery, fire alarms to name but a few.

Don't forget that most of these are business-critical if not safety critical so you'll need sufficient storage or backup generation to maintain them when your solar farm isn't producing enough power. I still think you're better off connecting to a DNO and letting the grid operators deal with all that. Donate any profits to the railway if your intention is to save them money on their energy bills.
 

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In addition, a lot of the station lights are continuously lit. Don’t under estimate how much electrical power the station lighting takes just on it’s own.

As well as the items you see in the public areas, there is also the lighting and heating / air conditioning for offices. Also heating, lighting, hot water boilers for drinking water, hot water for hand washing, fridges, computers etc for all the staff accommodation.

Obviously the actual amount depends on the size of the station, the number of retail outlets, the number of offices and the staff accommodation.

But for a large staffed station, this can easily be in the order of hundreds of kW of power even in summer.
 

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The signalling system uses a single phase 650V AC network that runs along the track side. It’s fed from a suitable DNO feed that has no other customers on it (guaranteed supply) and then feeds to a generator/switch room. The generator automatically starts up and takes over the load in the event of a loss of ‘mains’ supply. Optionally, the 650V AC supply from this then feeds to a large 650V UPS so that there is no loss of supply during the time that the generator takes to run up to speed and produce it’s output. The larger installations are rated in the order of 100kVA.

The supply for the electric point/switch rail heating is normally a convenient non-guaranteed 400V three-phase supply from a DNO. For smaller installations, it may be a 230V single phase supply. Only at very important junctions would you find a back-up generator.
SSP supplies are not fed from supplies with no other customers on them as that would be prohibitely expensive to take a feed from a Primary substation , they are standard dno supplies warts and all ( indeed some have real problems with voltages going out of specified limits at various times of days )

Points Heating supplies are Not fed from generator backed up supplies unless they are taken off a major station essential backed up supplies
 

Annetts key

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SSP supplies are not fed from supplies with no other customers on them as that would be prohibitely expensive to take a feed from a Primary substation , they are standard dno supplies warts and all ( indeed some have real problems with voltages going out of specified limits at various times of days )

Points Heating supplies are Not fed from generator backed up supplies unless they are taken off a major station essential backed up supplies
By no other customers, I mean the feeder cable going from the DNO substation to the railway without that cable feeding any other customers. Obviously the substations do have supplies to other customers. At least, that was the preferred arrangement on the Western for the late 1960s and the 1970s MAS schemes.

There may well be different arrangements elsewhere around the country.

In some installations, the railway took a 11kV supply. Then transformed it down to 400V using the railways own substations. This obviously was not only used to supply the 650V signalling supply, but the 11kV network also supplied locomotive depots, carriage works, stations, power boxes (domestic supplies) or other railway premises.

At one time, the railway had a standby generator for the point heating system at Westerleigh Junction (east of Bristol Parkway). This was entirely separate to the supply system for the signalling system. And this junction is nowhere near a station. I think it was in place for about five years, but the generator was removed some time ago. I agree that it’s not a typical arrangement.
 

aspire_13

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The signalling system uses a single phase 650V AC network that runs along the track side. It’s fed from a suitable DNO feed that has no other customers on it (guaranteed supply) and then feeds to a generator/switch room. The generator automatically starts up and takes over the load in the event of a loss of ‘mains’ supply. Optionally, the 650V AC supply from this then feeds to a large 650V UPS so that there is no loss of supply during the time that the generator takes to run up to speed and produce it’s output. The larger installations are rated in the order of 100kVA.

This 650V AC network supplies ALL the power required by the signalling system. Including for lineside colour light signals, point machines/point operating equipment, track circuits/axle counter equipment (train detection), and all the required circuitry and control equipment.

The supply for the electric point/switch rail heating is normally a convenient non-guaranteed 400V three-phase supply from a DNO. For smaller installations, it may be a 230V single phase supply. Only at very important junctions would you find a back-up generator. These systems are provided to prevent the points/switch rails from icing up or becoming overwhelmed with snow during winter weather.
What do you think should be the voltage from the inverter to the train station?
 
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