Broken Governer

[dexterdixon]

Hi.

I'm very inexperienced with anything to do with Hydro so please be gentle!

Some friends (9 families) have inherited a 35kW hydro setup on their land in Wales. It was refurbished and got up and running a year ago and produced them lots of lovely energy which made last winter much more comfortable. Unfortunately about 4 months ago the frequency started playing up (it's all battery-less off-grid) and the system was shut down.

I visited a few weeks ago and the whole system is in bits - apparently a bearing in the mechanical governor was dry which caused several other things to get bent and lead to... lots of things went wrong basically. As far as I can tell it's just the governor system that has problems though.

As winter approaches they're starting to get concerned as a community and would like to get it back online. They're also missing out on their feed in tariff which means there is an economic pressure to get it spinning again. Various bits have been sent off to be re-built by friends of friends but there is a fear it's all taking a bit too long.

My question is: Is it possible to run a system WITHOUT a mechanical governor at all and regulate everything using dump loads? Or would this cause more damage further down the line? It is an attractive option as they get paid the FIT for everything they generate - so regulating the water flow is ultimately going to regulate their income as far as I can tell.

They have one of these

http://www.retraceelectronics.com/Brochures/Brochure%20ELC%2045m.pdf

hooked into the 3 phase output and on a load of water heaters (and air heaters if the water gets too hot)

Only other thing I know is that it's a turgo-wheel made of brass and from the 1930's.

I can find out more information if needs be.

Sorry if it's a really silly question - this is the first hydro project I've ever been asked to help on.

Cheers,

Tom

[Flux]

Yes there are various electronic load control units that do control by dumping loads.

Your turbine is rather bigger than most of the small hydro schemes that use an electronic load control. You would probably need to manually set the flow to be in the right region for the load you were using and then let the electronic controller deal with small variations.

It sounds as though your scheme has a proper speed governor and it would be far better to get that back running in the long term but if you keep the load constant and the water level doesn't change rapidly you should be able to run it under manual control. The big issue would be a loss of load and that would let the turbine overspeed. Not a big issue on a small hydro but may be more serious with something your size.

The turbine will almost certainly be designed for 100% over speed but you may have to watch the alternator.

Much depends on the type of turbine, with a pelton with deflector you could probably arrange overspeed to deflect the jet until you shut it down.

Flux

[joestue]

that 45KW active load should be able to do it all on its own.

is the generator directly coupled, or is it 900,1800 rpm geared up from the turbine? the reason i ask is due to the inertia of the generator and turbine, there are likely some PID settings on that active load that might have been set to correct long term frequency drift, and to regulate short term voltage fluctuation, but now that the governor is out it isn't set up to handle the complete control loop.

how much variation in frequency are you dealing with?

[dexterdixon]

Thanks for your thoughts!

Ultimately we will get the governor back into action - there are just some noises coming from people nervous about the recent cold snap.

Flux - could you explain what you mean by a pelton and deflector setup (or should I just look it up?)

Joestue - from memory (I'm not currently there but will be in a couple of weeks) the alternator is coupled with a belt drive which looks like something around 20:1 but I'm not sure of either rpm to be honest. I can find this out over the phone tomorrow though.

Again in terms of frequency fluctuation I'm not sure - the first sign of trouble was "fridges making funny noises". My suspicion is that the electronic and mechanical systems may well have been playing off against each other causing some system resonance somewhere...
If you mean how much variation in load - the 9 families all have their own 2kW single phase feed from the central community building. They all got used to running bar heaters and dehumidifiers 24/7 last year. There are also 9 fridge-freezers clicking on and off independently which will no doubt be causing ripples. They don't use electric kettles though.

This is the first time I've touched anything this big, or battery less. It's quite intimidating!

There is some paperwork for the controller that I've asked to get sent - hopefully that will shed some light on the settings past and possible.

Cheers,

Tom

[Flux]

In view of the large speed increse it seems as though you don't have a Pelton Turbine.

It also seems from your description that the overall load is fairly constant but withoput knowing a lot more about the turbine and its method of control I would be reluctant to comment.

I agree that this is a big enough system to be fairly intimidating compared with the average pump induction motor of a kW or so. If the alternator was designed for hydro it will survive a load shed without governors but if it is a machine intended for engine drive you may be asking a lot.

As long as there is no risk of loosing load, you have a means of measuring frequency and the turbine is manually controllable you can probably run it under manual control.

flux

[keithturtle]

With the goal of restoring the feed-in tariff, your best option seems to get the mechanical governor fixed as soon as possible. 

It worked before, it must needs work again

IMO

Turtle