micro hydro

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junkhound

junkhound

Senior Member
Location
Renton, WA
Occupation
EE, power electronics specialty
Have a small stream where I could generate 1 to 2 kW. PM generator is various frequency ( 30 Hz to 1 kHz) depending on season and water flow and power level, want to do peak power tracking.

700 feet from cabin --

best option for transmission? raw ac (might only be 50 V gen output at 300W), dc, boost dc with inverter/rectifier to 300 Vdc, Even 400 Hz xfmr at 1 kHz high losses so ruling out boosting ac.

Loads primarily LED lights and refrigerator.
 
junkhound said:
Have a small stream where I could generate 1 to 2 kW. PM generator is various frequency ( 30 Hz to 1 kHz) depending on season and water flow and power level, want to do peak power tracking.

700 feet from cabin --

best option for transmission? raw ac (might only be 50 V gen output at 300W), dc, boost dc with inverter/rectifier to 300 Vdc, Even 400 Hz xfmr at 1 kHz high losses so ruling out boosting ac.

Loads primarily LED lights and refrigerator.
Click to expand...
I looked at one quite a few years ago. It was for the paper mill owner we did projects for. He liked the idea of free energy - who wouldn't! One project was the mill race that had been in disuse for decades but we got it in back operation. So he asked us to have a look at a stream some distance away. My recollection was that was potentially around 10kW. The problem was the cost to install cabling and the protection just wasn't viable.

You may have better options.
 
There are a bunch of people on YouTube who have done similar projects. You might want to look at them.

700 ft is a long way. I would be looking at battery storage near the generator and running ac back to the cabin at whatever voltage makes sense.
 
Tried that a few years ago at an old friends house.
Built a small weir, dug a diversion channel for flow through a water wheel we built from steel reels that HDPE comes on.
timed this thing at appx 12 rpm. Bought sprockets, pulleys, belts, jack shafts etc to get the generator up to speed. Used a genny from an old military unit that had a bad engine. (120/240 single phase)
ran about 500’ of 4/0 to the house, where the output fed nothing but (2) 50 gallon water heaters. One for domestic hot water, one for water that went through a coil for forced hot air.
The output was a little low, around 210-216, and the braking on the wheel was a little hard to get exactly right to hold it at the right RPM. But it worked fine for the water heaters. The output was low because we didn’t account for generator load when we timed the 12 rpm… dumb mistake.. too much aggravation to change pulleys so we left it for quite a while until he died (old age) and the son took it over. It just sits there now rusting away…
 
I took an online course in Small Hydropower at Online-PDH, course number SHS101, as part of my PE Continuing Ed requirement. It was pretty cheap and easy to understand.
 
junkhound said:
... PM generator is various frequency ( 30 Hz to 1 kHz) depending on season and water flow and power level, want to do peak power tracking.

... best option for transmission? raw ac (might only be 50 V gen output at 300W), dc, boost dc with inverter/rectifier to 300 Vdc, Even 400 Hz xfmr at 1 kHz high losses so ruling out boosting ac.
Click to expand...

Do you know if the losses and heating in the generator would be acceptable at 1 kHz as well? The core of the generator's stator will have losses from eddy currents and hysteresis just as a transformer would. Is there a larger generator that's suitable and can accommodate the flow but would not exceed 400 Hz?

With that large range in water flow and power levels, you would have better efficiencies and power output if there was a larger generator/turbine for the higher flows and a smaller one optimized for lower flows. This would also have a smaller range of generator output voltages that you would need to contend with. Of course it would cost more.

Because the magnitude of the magnetic field from the PM rotor is fixed, the open circuit voltage from the generator will be proportional to the rotor RPM by Faraday's law of induction (i.e., EMF is proportional to the rate of change of magnetic flux) . Therefore the volts/Hz from the generator will be substantially constant, which is optimal for the effective utilization of a transformer. And so I wouldn't immediately rule out using a transformer without further investigation.

By the way, I remember reading the following articles about getting power from small streams when I was a kid. They were from very old Popular Mechanics left by the previous owner of the house. My brothers and I found them fascinating even though we had no chance of doing anything with it.

https://books.google.com/books?id=v...=2ahUKEwjgkISbneL4AhWUg4kEHW1lCFAQ6AF6BAgCEAM

https://books.google.com/books?id=o...from Small Streams" Popular Mechanics&f=false
 
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