Vivarail chosen for fast charging trial on the Greenford branch

[whole diary]

[JayMac]

A 32 amp 3 phase supply would probably fully charge it overnight, and even a domestic type 13 amp supply would charge it in a few days.

Even better, use a four way extension lead and you could charge a small fleet all at the same time. Simples.

Long enough flex with a spring winding system and you could leave the train plugged in.

[eightonedee]

Quote from: Celestial on Yesterday at 08:14:27 pm
Quote from: broadgage on Yesterday at 06:58:32 pm


A 32 amp 3 phase supply would probably fully charge it overnight, and even a domestic type 13 amp supply would charge it in a few days.

Even better, use a four way extension lead and you could charge a small fleet all at the same time. Simples.

Long enough flex with a spring winding system and you could leave the train plugged in.

Not a bad idea BNM. But I have had another - how about suspending two conducting wires side by side above the track, put some kind of pick up apparatus on the roof of the train, and do away with those heavy (and expensive to produce from all kinds of rare materials whose extraction and processing is I understand not particularly environmentally friendly) batteries?

[TonyN]

Long enough flex with a spring winding system and you could leave the train plugged in.

Why bother with the flex just use clockwork. Could have a motor at West Ealing and Greenford to wind it up before each trip.

[grahame]

The irony - from Ian Visits

Former London Underground District line trains are returning to London.

This happens to means that during the trial, Greenford station, which is on the Central line, will also be served by ex-District line trains.

[broadgage]

Quote from: Celestial on Yesterday at 08:14:27 pm
Quote from: broadgage on Yesterday at 06:58:32 pm


A 32 amp 3 phase supply would probably fully charge it overnight, and even a domestic type 13 amp supply would charge it in a few days.

Even better, use a four way extension lead and you could charge a small fleet all at the same time. Simples.

Long enough flex with a spring winding system and you could leave the train plugged in.

Not a bad idea BNM. But I have had another - how about suspending two conducting wires side by side above the track, put some kind of pick up apparatus on the roof of the train, and do away with those heavy (and expensive to produce from all kinds of rare materials whose extraction and processing is I understand not particularly environmentally friendly) batteries?

You would not even need two wires ! One wire will work fine with the steel rails forming forming the other side of the circuit.
Various voltages have been used, recent trends have been towards relatively low DC^▸ (Direct Current) voltages of from 550 volts up to 1,500 volts for shorter lines in urban areas, and with 25 kv AC finding favour for longer routes.

Both are lethal if touched but reasonably safe as well out of reach.

[oxviem]

My understanding is that a battery storage bank allows a reservoir of power to be built up off solar power, or perhaps off a limited mains supply, over a period of time for a short, sharp local charge.  Bit like a reservoir, but for power not water?

Could this technology also be applied (indeed, is it already applied?) to electric charging for road vehicles - could (for example) a couple of buses running a town service be fast-charged during the driver's personal needs break, even if the grid to the place that break is taken is pretty pathetic?

Indeed it already is in the UK^▸ (United Kingdom) too - see the electric buses in Harrogate. https://en.wikipedia.org/wiki/Harrogate_Bus_Company

[grahame]

My understanding is that a battery storage bank allows a reservoir of power to be built up off solar power, or perhaps off a limited mains supply, over a period of time for a short, sharp local charge.  Bit like a reservoir, but for power not water?

Could this technology also be applied (indeed, is it already applied?) to electric charging for road vehicles - could (for example) a couple of buses running a town service be fast-charged during the driver's personal needs break, even if the grid to the place that break is taken is pretty pathetic?

Indeed it already is in the UK^▸ (United Kingdom) too - see the electric buses in Harrogate. https://en.wikipedia.org/wiki/Harrogate_Bus_Company

Thanks for that link - really interesting to read into the Harrogate project (which I have been doing while supping my coffee!).   I can't see a note there of how the power gets to the rapid chargers.   Do they have a battery storage reservoir at the charging points (which is what I am especially interest in with the Ealing experiment) so they can be filled up with a pathetic mains connection while there's no bus on stand, or is there a thumping great substation behind the bus station?

[stuving]

For the Volvo 7900e (as in harrogate) the rooftop connector and the rather clunky "socket" it plugs into are of a proto-standard design called OppCharge. This appears to be led by ABB, but who makes the bits is less clear. The idea of promoting it as a standard is obviously that buyers don't want to be limited to a single supplier for new buses to use their chargers.

The draft standard says rather cheekily that there is no upper limit to the current (presumably referring to the standard's text, not to any real equipment). The voltage is in the nominal range 500-800, typically 700 or 750, and at the moment the maximum current is 600 A. ABB say their chargers can offer 150, 300, or 450 kW (i.e. 750V x 600A), citing ones in Brussels that can fully recharge Volvo electric hybrid buses in three to six minutes. But that's electric hybrids - with a diesel engine, so presumably a smaller battery.

The 7900e data sheet says its capacity can be 198, 264 or 330 kWh, and when using OppCharge is can accept 300 kW (or 150 kW DC^▸ (Direct Current) or 11 kW AC via a plug-in lead). Obviously that's not going to do a complete charge from empty in six minutes! 300 kW at 400 V is roughly the total capacity of a typical substation circuit like mine. So it's reasonably easy to provide if a substation is nearby, otherwise you'll need an 11 kV feed, which could give a higher peak power.

Essentially, at the moment local buffering is a non-standard extra, and that's probably how VivaRail justify their otherwise rather implausible claim that their kit is first-of and patentable.

[Celestial]

https://www.bbc.co.uk/news/av/business-48764903

An interesting report from a couple of years ago in Guildford, where a storage facility is used to draw charge from the grid during the day to avoid putting too much pressure on the local supply overnight.  That's only for 9 buses as well.

[stuving]

https://www.bbc.co.uk/news/av/business-48764903

An interesting report from a couple of years ago in Guildford, where a storage facility is used to draw charge from the grid during the day to avoid putting too much pressure on the local supply overnight.  That's only for 9 buses as well.

I suspect that should be seen as more of a supply-side storage battery. There are a lot pf places, especially (but not only) more rural ones, where there is no spare supply capacity further up the distribution chain. That's not just an issue with very short high-power peaks: you'd need to shift the load out of the main daytime high load periods into the night.

The supply industry (DNOs^▸ (Distribution Network Operator), mainly) are trying to work out how to interact with customers' own storage, but also looking at having their own. A few years ago there was a research project here (with SEPD as DNO) on storage distributed in the local network (i.e. street corners), to even out the load.

All of these general-purpose storage units interface to AC mains via an inverter/converter. This kind of local reinforcement is compatible with a "normal" charge rate, but with a high cost if required to supply a really high power peak for a very fast charge and/or a big battery.

[Electric train]

There is an over generation of renewable (solar mainly) in parts of the country, the problems are the DNO^▸ (Distribution Network Operator)'s do not always have the infrastructure to get this back to a TNO^▸ (Transmission Network Operator) site. 

Its more complex than just feeding it backwards. The UK^▸ (United Kingdom) power network was designed and engineered bulk generating plants cascading power down to the end user, the DNO's and TNO are working to get the infrastructure in place but it takes time and money.

The lineside storage is a bit akin to the days of steam and the water tanks which had a trickle feed into them but had the ability to "charge" the tender of a locomotive quickly.

I believe the Vivarail will be a contact system in the four foot, the original concept was for a short length ( 3 or 4 metres) of standard type third or fourth rail, neither NR^» (Network Rail - home page) or the ORR^» (Office of Rail and Road formerly Office of Rail Regulation - about) were keen on that on safety grounds.   The collection contacts will only be energised when the train is stopped in the right place and the brakes applied. 

Charging at 300kW should not be an issue, if the previously stated 60 miles on a single charge is correct the unit will only need charging once it arrives at West Ealing from Reading TCD and then before it returns back to Reading TCD at the end of the day.

[Celestial]

Charging at 300kW should not be an issue, if the previously stated 60 miles on a single charge is correct the unit will only need charging once it arrives at West Ealing from Reading TCD and then before it returns back to Reading TCD at the end of the day.

How does that work? If it's a half hourly service on a 5 mile return trip then it would need recharging at least every 6 hours. And surely better to get used to topping up every time so that there are as many opportunities as possible to ensure that the process is robust and works every time, even if time constrained.

[TonyK]

Not certain that the intention is to charge the lineside battery from solar ? The publicity material seems to imply that this is an option.
In an urban area of the UK^▸ (United Kingdom) with substantial grid supplies, I am not convinced that the lineside battery is justified. This battery adds costs, complication, extra losses, and another point of failure.

Loads of up to about 1 MW can be supplied direct from the 11kv DNO^▸ (Distribution Network Operator) network, if more than that is needed than a higher voltage supply is needed. This costs money, but is probably cheaper than the lineside battery.

The publicity does indeed suggest that it can be charged from solar panels, as can any battery. It looks good, and impresses the green lobby more than saying that it will be charged by electricity produced by a mixture of solar, wind (not solar wind), nuclear, coal and predominantly gas. The Cancun 3-car model could be powered by a solar array spread over 3.4ha according to the leaflet, a space which would probably see about 250 homes built on it were it to become available. I assume therefore that not only is it sunny in Cancun, but that land is cheap. Given the weather here, you would probably need most of Greenford covered in panels if you were to rely on that.

A 3-car train uses 9 kWh per kilometre. Greenford to West Ealing and back is 8 km, so the charge at each turn at the charging station would be in the order of 72 kWh. To do that in 10 minutes is quite an accomplishment - would that need a >400 kW charge? That seems far too high, so I assume I misunderstand the maths and/or physics.

[paul7575]

A 3-car train uses 9 kWh per kilometre. Greenford to West Ealing and back is 8 km, so the charge at each turn at the charging station would be in the order of 72 kWh. To do that in 10 minutes is quite an accomplishment - would that need a >400 kW charge? That seems far too high, so I assume I misunderstand the maths and/or physics.

Looks about right to me, but for an accurate calculation you’d also have to look at the time spent decelerating and hence regenerating. 

But if you think about it another way, if the short relatively lightweight unit draws about 100A on average from its supply when moving, you’d have to expect many times that during the much shorter charging phase.  If you round up the typical DC^▸ (Direct Current) line voltage to 800V, then 500A would give you your 400kW.  Of course with their shoreside battery bank they can use a voltage of their own choosing, within reason.

So I think you’re in the right ballpark.

Paul

[broadgage]

400 kw is in theory just about doable at UK^▸ (United Kingdom) standard supply of 415/433 volt three phase. It would however be a very "disturbing" load to add to the ordinary LV distribution system.

A dedicated substation supplied at 11 kv would probably be required. In a built up area, providing an extra substation is routine and probably cheaper than a local battery. The substation transformer and other equipment should last at least 50 years.
Any local battery would almost certainly need replacing many times in 50 years.

Another advantage of a dedicated substation is that the transformer may be of a suitable voltage for the fast charger, rather than incurring the capital cost and the losses in transforming 415/433 volts up the charging voltage.

Ideally fast charging should be available at BOTH ends of the line, but the on board battery capacity should enable a normal service to be operated with charging only available at one end. In case of transformer failure or local power cut.



There is also the NIMBY factor, I and many other people would oppose a large lithium battery near my home in case of accident. A local substation would no problem.