BEMUs and on-route charging

[Nicholas Lewis]

I was considering a shrouded system (bottom or side contact) for a battery charging facility on a standalone route where no existing power supply is available - or at least no live-rail system. If battery operation is envisaged to extend a service beyond the limits of an existing 3rd rail system (e.g Wrexham, Uckfield, Helsby, Skelmersdale, Preston via Burscough - even possibly Aylesbury or Salisbury), batteries can be topped up whilst the train is running on that part of its route which is part of the existing "grandfathered" legacy live rail network.
In some cases, such as Bidston, it might require extended dwell time at the electrified terminus, or extending services beyond the existing terminus.

The optimal solution is routes where you can get off an electrified section to a terminus and return back without having to recharge so will be interesting to know what VivaRails 230 BEMU battery capacity is. Although in reality the industry needs to decide how much reserve a train should have to keep air con and loos going on top the functional needs of the safety and traction system to cover for operational incidents. This will affect the useable amount of stored energy that can be used for movement so on paper VivaRails 80miles will have to be less for diagramming purposes.

 

[Ken H]

The optimal solution is routes where you can get off an electrified section to a terminus and return back without having to recharge so will be interesting to know what VivaRails 230 BEMU battery capacity is. Although in reality the industry needs to decide how much reserve a train should have to keep air con and loos going on top the functional needs of the safety and traction system to cover for operational incidents. This will affect the useable amount of stored energy that can be used for movement so on paper VivaRails 80miles will have to be less for diagramming purposes.

There was a pile up on the M62 a few years go and people were stuck on the motorway for a few hours. Then they had a shedload of EV's with flat batteries to shift. People needed the heaters because it was a freezing night. So a train thats stuck for a while could be in trouble.

 

[zwk500]

There was a pile up on the M62 a few years go and people were stuck on the motorway for a few hours. Then they had a shedload of EV's with flat batteries to shift. People needed the heaters because it was a freezing night. So a train thats stuck for a while could be in trouble.

No different from an EMU when the wire are off. In fact probably better off, because the EMU can at least get to the next station and give people the option of getting off (or even having an emergency supply cable that can connect to a station outlet).

 

[Bald Rick]

Uckfield is a fair way from Hurst Green. Would an out and back working exhaust the batteries on a winters day (Lights, heating, wipers etc all on) or would it need a top up at Uckfield?

Depends on the size of the battery of course. But given that’s 50 miles from Hurst Green to Hurst Green via Uckfield, and there are battery units running around in Germany with 80miles+ range, the answer is clearly ‘yes’

If they were to have top contact conductor rail only live when a train was there, how would you cope with different length trains?

By sectioning the con rail and linking it to some form of train detection. Easily done.

And is that sort of power available from the local power network?

Yes it is. Albeit most likely to be lineside batteries trickle charged - again a solution in use elsewhere (and has been looked at for Uckfiled specifically).

 

[hwl]

The optimal solution is routes where you can get off an electrified section to a terminus and return back without having to recharge so will be interesting to know what VivaRails 230 BEMU battery capacity is. Although in reality the industry needs to decide how much reserve a train should have to keep air con and loos going on top the functional needs of the safety and traction system to cover for operational incidents. This will affect the useable amount of stored energy that can be used for movement so on paper VivaRails 80miles will have to be less for diagramming purposes.

It isn't just about capacity but charging rate.
For reasonable cost for the next 5years (or more) you can choose either:
a) high capacity (high mileage)
b) high charging rate (quick turnarounds)

If you want both (Vivarail territory and DfT's dreamworld) that is very expensive and will be for a while yet. I mean eye wateringly expensive though I'm not sure that penny gold bar has dropped on DfT's foot yet.

== Doublepost prevention - post automatically merged: 11 Oct 2021 ==

Depends on the size of the battery of course. But given that’s 50 miles from Hurst Green to Hurst Green via Uckfield, and there are battery units running around in Germany with 80miles+ range, the answer is clearly ‘yes’

But not with high charging rates

Yes it is. Albeit most likely to be lineside batteries trickle charged - again a solution in use elsewhere (and has been looked at for Uckfield specifically).

Lineside batteries will possibly get used for the GWR Greenford trial.

 

[Nicholas Lewis]

Uckfield is a fair way from Hurst Green. Would an out and back working exhaust the batteries on a winters day (Lights, heating, wipers etc all on) or would it need a top up at Uckfield?

That scenario would be determining factor in sizing the battery capacity but I suspect with current energy density of batteries for this duty there isn't enough space in the underframe of a class 377 - 4 car

Would trains stabled at Uckfield need topping up overnight to get them to Hurst Green?

that would have to be factored into battery sizing if it was a requirement

If they were to have top contact conductor rail only live when a train was there, how would you cope with different length trains? A 4 car would leave exposed 3rd rail. if you only had a 4 car length electrified then it would not work with units in multiple.

The switching system would only energise what is necessary and that would have to be demonstrated in teh safety case as having a high intrinsic safety level against false energisation

And how many trains would you stable at night. How much demand would they have? What would all that kit cost. And is that sort of power available from the local power network?

VivaRails solution of using local batteries to provide the oomph for rapid charging limits the demand on local grids but if it were necessary to recharge every hour that installation would have to be sized to deliver that frequency across 18hours with recharge overnight.

How would you stop a train starting drawing big amps from the 3rd rail and tripping the circuit breakers?

If your referring to when its charging from a remote location there would be software interlocks to prevent a driver demanding traction power when the train is charging. When the train is running on 3rd rail it will continue to have a current limit but can easily blend managing overall demand between traction and battery charging. ie when its pulling full power accelerating away from a station won't be any battery charging but when its coasting or stationary it will be charging. Also of benefit is when its braking it will have a ready made load, the battery, to absorb that energy. This has been proven by other countries running BEMUs to improve overall efficiency compared to regen back into the traction system.

 

[Bald Rick]

That scenario would be determining factor in sizing the battery capacity but I suspect with current energy density of batteries for this duty there isn't enough space in the underframe of a class 377 - 4 car

I understand there is both enough space and enough ‘spare’ weight.

The rest of your post is spot on.

 

[Nicholas Lewis]

I understand there is both enough space and enough ‘spare’ weight.

The rest of your post is spot on.

Good to know and with plenty of spare units available currently shame they don't just get one converted and trial underway then.

 

[James James]

Stationary pantographs are limited to how much current can be transferred across the interface without causing overheating which is a problem for rapid charging as it needs high current transfer albeit for a limited period of time whereas shoegear has a much higher surface area to transmit the current. Charging via AC is going to need a transformer to be lugged around and not sure there is room under a D78 for one.

That's a distraction, just like 25kV OHLE is a distraction. If you're building a charging-only section of OHLE you can not only specify whatever voltage you want (avoiding transformers), you also don't need to use a thin bit of wire (subject to overheating issues). The PKP were able to come up with rail-based OHLE using multiple conductors for the use-case of 250km/h under 3kV DC (although I think they later decided to just go for 25kV), likewise someone in the UK could come up with OHLE to allow high-current charging for a BEMU.

Obviously you'd have to bin that special OHLE if you ever wire the whole line (but you'd be doing that anyway for either sysyem), but in the meantime it's a cheap and efficient way to charge your train.

 

[hwl]

Good to know and with plenty of spare units available currently shame they don't just get one converted and trial underway then.

The problem as I have mentioned before is that there is minimal spare capacity on the bits of the 3rd rail network where you would be powering these units on 3rd rail (instead of DMU) and secondly you are then also wanting to charge these units on power constrained section when the power isn't available for traction.

 

[Bald Rick]

The problem as I have mentioned before is that there is minimal spare capacity on the bits of the 3rd rail network where you would be powering these units on 3rd rail (instead of DMU)

Well, there wasn't spare capacity (at peak times). There is now. But the same applies whether it is a Battery EMU or a plain vanilla EMU.

secondly you are then also wanting to charge these units on power constrained section when the power isn't available for traction.

Just as well they don’t need power for traction all the time they are on the juice

 

[Nicholas Lewis]

The problem as I have mentioned before is that there is minimal spare capacity on the bits of the 3rd rail network where you would be powering these units on 3rd rail (instead of DMU) and secondly you are then also wanting to charge these units on power constrained section when the power isn't available for traction.

There are two parameters that affect available traction power supply capacity. Firstly the power demand of the trains, there formation ie 4/8/12 and frequency of trains are used to size the trackside traction substations and there spacing. Once thats fixed the signalling system will act as a constraint. The East Grinstead line into London Bridge or Victoria already has trackside substation capacity to deliver 12 coach trains at 2 to 5 minute headway depending upon location. The second parameter is how many trains are on the move simultaneously which impacts the high voltage distribution system which supplies power from the grid connection points to the trackside substations.

Since the introduction of replacement slam door stock the additional power of these trains has pushed some grid connections over their available capacity and NR has been progressively, over the last decade, seeking additional capacity from UK Power Networks. Some locations can readily provide capacity but others need work by UK Power Networks. Specifically South London (serving routes out of CX, Blackfriars and Victoria) is supplied from New Cross Grid, which incidentally is NR's biggest 3rd rail supply point, but UK Power Networks couldn't support the additional load requested so the traction load had to be transferred to the national Grid 275kv substation which takes time. NR has been progressing this project for nearly a decade but it was finally commissioned in Mar 2020 (enhancement project K004) and as a result this provides sufficient extra power for South London.

There will be no issue in the existing electrified route supporting BEMU's on the Uckfield Line.

 

[SynthD]

Since the introduction of replacement slam door stock the additional power of these trains has pushed some grid connections over their available capacity and NR has been progressively, over the last decade, seeking additional capacity from UK Power Networks. Some locations can readily provide capacity but others need work by UK Power Networks. Specifically South London (serving routes out of CX, Blackfriars and Victoria) is supplied from New Cross Grid, which incidentally is NR's biggest 3rd rail supply point, but UK Power Networks couldn't support the additional load requested so the traction load had to be transferred to the national Grid 275kv substation which takes time. NR has been progressing this project for nearly a decade but it was finally commissioned in Mar 2020 (enhancement project K004) and as a result this provides sufficient extra power for South London.

That's interesting. Are there any similar projects ongoing or coming up?

 

[Ken H]

There are two parameters that affect available traction power supply capacity. Firstly the power demand of the trains, there formation ie 4/8/12 and frequency of trains are used to size the trackside traction substations and there spacing. Once thats fixed the signalling system will act as a constraint. The East Grinstead line into London Bridge or Victoria already has trackside substation capacity to deliver 12 coach trains at 2 to 5 minute headway depending upon location. The second parameter is how many trains are on the move simultaneously which impacts the high voltage distribution system which supplies power from the grid connection points to the trackside substations.

Since the introduction of replacement slam door stock the additional power of these trains has pushed some grid connections over their available capacity and NR has been progressively, over the last decade, seeking additional capacity from UK Power Networks. Some locations can readily provide capacity but others need work by UK Power Networks. Specifically South London (serving routes out of CX, Blackfriars and Victoria) is supplied from New Cross Grid, which incidentally is NR's biggest 3rd rail supply point, but UK Power Networks couldn't support the additional load requested so the traction load had to be transferred to the national Grid 275kv substation which takes time. NR has been progressing this project for nearly a decade but it was finally commissioned in Mar 2020 (enhancement project K004) and as a result this provides sufficient extra power for South London.

There will be no issue in the existing electrified route supporting BEMU's on the Uckfield Line.

With the dire state of the UK power network, and lack of generating capacity, I think we can expect problems in the future for the railway to get the power it needs. In a February anticyclone (no wind, cloudy, short days, cold) we could well run out of power leading to load shedding by the grid. That could affect electrification (tho I believe the railway has priorty for supply), low frequency and also power cuts to stations, leading to short term closures. It was pretty dire in part of last month - they had to use coal fired stations (West Burton, I believe) to ensure there was enough power.

 

[hwl]

Well, there wasn't spare capacity (at peak times). There is now. But the same applies whether it is a Battery EMU or a plain vanilla EMU.

Just as well they don’t need power for traction all the time they are on the juice

Wasn't, indeed who knows what the future holds)
What it does meant is that you need pretty well thought out charging software integrated into the TCMS including GPS geofencing capabilities to avoid supply issues, it isn't as simple as it looks.

There are two parameters that affect available traction power supply capacity. Firstly the power demand of the trains, there formation ie 4/8/12 and frequency of trains are used to size the trackside traction substations and there spacing. Once thats fixed the signalling system will act as a constraint. The East Grinstead line into London Bridge or Victoria already has trackside substation capacity to deliver 12 coach trains at 2 to 5 minute headway depending upon location. The second parameter is how many trains are on the move simultaneously which impacts the high voltage distribution system which supplies power from the grid connection points to the trackside substations.

Since the introduction of replacement slam door stock the additional power of these trains has pushed some grid connections over their available capacity and NR has been progressively, over the last decade, seeking additional capacity from UK Power Networks. Some locations can readily provide capacity but others need work by UK Power Networks. Specifically South London (serving routes out of CX, Blackfriars and Victoria) is supplied from New Cross Grid, which incidentally is NR's biggest 3rd rail supply point, but UK Power Networks couldn't support the additional load requested so the traction load had to be transferred to the national Grid 275kv substation which takes time. NR has been progressing this project for nearly a decade but it was finally commissioned in Mar 2020 (enhancement project K004) and as a result this provides sufficient extra power for South London.

There will be no issue in the existing electrified route supporting BEMU's on the Uckfield Line.

I'm fully aware of the New Cross supply upgrades and the decommissioning of the old oil filled 66kV cable network. The areas with potential supply constraint issues are south of Anerley and outside the New Cross supply area and have been covered in plenty of threads involving Uckfield.

 

[Nicholas Lewis]

What it does meant is that you need pretty well thought out charging software integrated into the TCMS including GPS geofencing capabilities to avoid supply issues, it isn't as simple as it looks.

Agreed but the TCMS software already restricts maximum current draw by the train so my view is charging isn't extra total train demand just substituted demand when the train isn't motoring. So the DC traction system isn't being asked to deliver anything more than its already required to do so but I acknowledge overall demand on the grid system will be increased from charging but within a largely electrified area it will be a small increment. What will need understanding is whether sufficient charging time is available when the train isn't motoring and whether the battery life will be impacted by erratic charging.
As this idea was floated for the Uckfield line several years ago one wonders how far they got into understanding these issues.

 

[Bald Rick]

As this idea was floated for the Uckfield line several years ago one wonders how far they got into understanding these issues.

There’s is a good level of understanding.

 

[edwin_m]

Agreed but the TCMS software already restricts maximum current draw by the train so my view is charging isn't extra total train demand just substituted demand when the train isn't motoring. So the DC traction system isn't being asked to deliver anything more than its already required to do so but I acknowledge overall demand on the grid system will be increased from charging but within a largely electrified area it will be a small increment. What will need understanding is whether sufficient charging time is available when the train isn't motoring and whether the battery life will be impacted by erratic charging.
As this idea was floated for the Uckfield line several years ago one wonders how far they got into understanding these issues.

One constraint on power supplies is thermal. When supplying current they heat up, and they cool down when the current demand reduces. So it's possible for the loading on a power supply to become unacceptable if the same current is being demanded for a longer period. I don't know if this is actually a constraint in this case, but it's a factor that will need to be considered, particularly on the extremities of the electrified network where the extra demand could be a significant proportion of the baseline.

 

[Ken H]

Spinoff thread re leccy supply issues and sizing https://www.railforums.co.uk/threads/is-the-leccy-supply-to-the-railway-just-enough.223570/

 

[Chris125]

Greenford is an open competition, not necessarily Vivarail's for the taking!

That's technically true but the timescales alone made them overwhelmingly favourite, and the Vivarail website confirms their involvement:

"Regulators were always involved and all elements of risk fully understood. That task was successfully achieved and the next step identified – a year-long live trial on the national network. With assistance from the UK’s Department for Transport and Network Rail, Fast Charge’s trial is due to start in early 2022 on the West Ealing-Greenford line in London, after that it will be fully approved for use on the network for all types of battery train."

Vivarail It was good while it lasted.

vivarail.co.uk

 

[D365]

Vivarail (at least since they started development of their battery train system) has always been eying up routes such as Greenford branch.