Pico Hydro - Controling Generation

[Lesgrandepotato]

So I'm looking at some home hydro technology - I've figured out the basic control system - I'll route it around and switch it in and out using the Fibaro HC2 that is controlling the rest of the building. So we can have a water level sensor on the run into the leet, and in the culvert to trigger for any fault / low level conditions - we'll use a signal from the Thermal store - either direct from the thermostat or via a Z wave thermostat to sense load requirement. 

 

So that just leaves the question what to do with the excess load, I could route it to a dump load, but that would need a potential 3kw load that doesn't trip out - so in the first instance it'll get fired into the Towel rail circuits (but thats not enough load), but the question that springs to mind is could I simply drop the excitation current from the genny and let it run into the towel rails? I'd expect to need some load in case of back EMF in the genny making power? 

 

Or am I over thinking it and I just need to switch of the excitation current? Naturally we could do it all wet side (stop the water flow), but that seems more prone to jamming and failure than this approach? 

[ProDave]

If you are talking of 3KW generation, I would hardly call that "Pico Hydro"  My own scheme I am thinking of would probably generate 100W, that certainly is Pico and I won't worry where to dump excess generation.

 

Surely in your situation you would close of the water and shut it down if the dump load has shut off? Even better would be to modulate the water flow so generation = usage?

[A_L]

Quote

So that just leaves the question what to do with the excess load, I could route it to a dump load, but that would need a potential 3kw load that doesn't trip out

 

Just in case you are unaware, some micro-hydro generators have a built in dump load that can take all the output and heats the flowing water.

[Nickfromwales]

1 hour ago, Lesgrandepotato said:

So that just leaves the question what to do with the excess load,

Hence my suggestion ( in your other thread ) of a much bigger TS. Further comments there on cylinder type / size / configuration so as to keep this thread on topic. 

[Lesgrandepotato]

1 hour ago, ProDave said:

If you are talking of 3KW generation, I would hardly call that "Pico Hydro"  My own scheme I am thinking of would probably generate 100W, that certainly is Pico and I won't worry where to dump excess generation.

 

Surely in your situation you would close of the water and shut it down if the dump load has shut off? Even better would be to modulate the water flow so generation = usage?

ProDave, my concern with that is making it fool proof, the Millstream is running through a wood and I forsee issues with leaves / twigs / trees jamming any mechanical elements - hence the desire to let the water run (we have a massive underground culvert to channel through) and then simply disengage the electrical side? 

[Jeremy Harris]

8 minutes ago, Lesgrandepotato said:

ProDave, my concern with that is making it fool proof, the Millstream is running through a wood and I forsee issues with leaves / twigs / trees jamming any mechanical elements - hence the desire to let the water run (we have a massive underground culvert to channel through) and then simply disengage the electrical side? 

 

That's the easy bit, you just create a self-cleaning overflow filter weir, that allows excess water to flow over the top of a grill and sweep the debris away.  There will be lots of designs around on the web, but if you get stuck I can sketch up the system used at the caving club I used to belong to, that gets it's water supply from just such a system, that's then connected to a few hundred metres of large bore MDPE that runs down the mountain to the club house.  In essence it's just like a hydro system, and there's no problem at all in just turning the water off at the end of the pipe when water isn't needed.

 

Paul Camelli, up at the end of Raasay, has a similar setup running his hydro power system, and has documented what he's built pretty well on his blog - well worth a read:  https://lifeattheendoftheroad.wordpress.com/

 

(you'll need to search back a few years for his hydro stuff)

[Lesgrandepotato]

Cheers JSHarris this place is a goldmine of little nuggets of info - I'll have a read tonight :-) 

[PeterW]

@Lesgrandepotato you would only divert after the point you've filtered. You need a pair of automatic gate valves that allow you to divert an amount of flow before it hits the nozzle. This can be used to both control flow and also output. 

 

Fairly easy to do with some basic proportional control 

 

 

 

[SteamyTea]

Here is a picture of a filter on a small hydro system near me.

When I say small, it is 200 kWp I seem to remember.

 

 

[Triassic]

Paul at end of the road dumps the excess heat into his garage workshop.

[Lesgrandepotato]

Starting to get a bit more in-depth with this. Plan is to create a wooden intake with  a 100mm outlet. This can be sited and we’ll see if 100mm is a viable pipe size if so, we’ll probably then run two 63mm mdpe’s down to a plenum and then stick a nozzle on it and see how high we can squirt some water ? 

[Jeremy Harris]

5 minutes ago, Lesgrandepotato said:

Starting to get a bit more in-depth with this. Plan is to create a wooden intake with  a 100mm outlet. This can be sited and we’ll see if 100mm is a viable pipe size if so, we’ll probably then run two 63mm mdpe’s down to a plenum and then stick a nozzle on it and see how high we can squirt some water ? 

 

 

Take care with where you site and operate valves!  I've heard of someone who put a shut off valve at the dam end, and when the valve closed the suction from the momentum of the water still rushing down the pipe squashed a bit of MDPE flat (large bore, too think it was at least 63mm).  Valves at the bottom can also be tricky, apparently, as stopping a moving column of water can create a pretty high pressure pulse (it's how pulse pumps work - I helped fix a Victorian one once, that was sat in a small stream).

[Lesgrandepotato]

I’m thinking about bleeding off as opposed to a full stop when I have a pelton/turgo on it. 

[PeterW]

I’ve seen this done and basically you need a pair of gate valves (one flow and one divert) and you encase the whole Y branch in concrete as it will move otherwise ..!! Can sometimes be easier to convert to iron and use flanged valves and flanged Y branches than MDPE - it’s not that expensive either.