Case Study: Building Your Own 20kW Hydroelectric Power Plant

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Automation & Control

Building your own power plant

William K.  
11/21/2011 8:11:11 PM

I also read the article in the Automation Direct publication. and I found it fairly interesting. I can certainly imagine that there would be a whole lot of government people wanting to have control over exactly how it was done. 

The method of using standard induction motors driven a bit faster than synchronous speed was quite interesting. I can understand needing to have some belts that could slip, as a means of allowing the motors to synchronise with the mains power, because otherwise it would not work. It is also probably the cheapest approach, although it may not be the most efficient. My choice would be to drive three phase alternators and then convert the power to the correct frequency using a switching cycloconverter. That is more costly, however. The advantages are that one single device could be controlled to deliver the desired amount of power, and the generator would not need to have the drive speed controlled so precisely. Besides that, I like alternators more. 

One interesting thought is that one of the older mecanical meters could be driven backward quite simply, but the newer generation of smartmeters could easily be programmed to not run in reverse. In addition, It is certain that the power company could pull all kinds of tricks with the smartmeter programming.

One last comment is that it would be interesting to see a detailed description of both the mechanical and the electrical design of the system.


Jim, I agree. That’s mind-boggling. But here in California, for decades PG&E fought solar power in homes tooth and nail. A once-famous local columnist, Herb Caen, once famously said “PG&E wants to put a switch on the sun.” When PG&E finally had to give in, it then fought buy-back for many more years.

What part of free is so tough to get? I think it’s actually about control, not about free.


-rant over- [for now]

Re: Hydro power

Froese  
11/19/2011 8:11:30 PM

“It is easier to ask forgiveness than permission.” Seriously, the environmental impact is minimal since the lake has been there for 100+ years, and there was already a spillway here. Regarding utility interconnection and net metering, our state (South Carolina) does not have rules and regulations for this yet and our local electrical co-op was actually quite helpful and generous in this regard. I’m quite certain that if we had to fulfill all the environmental, engineering, seismic, etc. regulations California has, this project would have been a “no go.”

Re: Details, please!!

Froese  
11/19/2011 8:03:18 PM

The main belt (from the turbine shaft to the secondary shaft) is toothed, but the belts to each individual motor/generator are ordinary v-belts. We have found that the slippage allows them to synchronize. On rare occasion, when starting starting a generator after other(s) have been running for sometime, it can be 180 degrees out and cause the breaker to trip, but most of the time they seem to sync up by themselves in a fraction of a second.

Froese, thanks for taking the time to respond to my question. You have done something I wish to do, although my application would be a pelton wheel system since I have fairly low flow but a  900 foot head.

It looks like you took the time to research the highest efficiency in belt power transmission- are all your drives toothed belting? The video is not clear–the main drive from the turbine looked like it might be a multiple v-belt setup but the motor drives certainly looked like toothed belt drives.  Do the toothed belt drives on the motors allow for automatic synchronization of all three motors with each other? Did you have to play with the shaft orientation on each motor to get all three sinewaves from the motors to coincide?

Congratulations on your efforts!  You can be justifiably proud of your accomplishment. And I probably will investigate Automation Direct as well!

Jon.

Ann: Taking a quick look on the Internet, it appears that many states (possibly as many as 40?) have buyback programs, but it’s not clear if that energy buyback is mandated.

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