opinions about wind generators

Re: opinions about wind generators

On the subject of "light wind" sites and the Whisper 200 in particular....

I have a 1.3kW solar array for a battery backup system with 22kWh of batteries and OutBack inverters. The system works great (except for the FLEXnetDC monitoring tool which I don't care for at all). I put up a Whisper 200 on a 30' pole. The 30' is a zoning issue and avoided hassles. It is 30' too short!. The Whisper 200 went up before the solar array and for a month or two generated approximately 2kWh per day. That was very close to the desired rate. 2kWh/day, would return the 30 cents, or so, per day that the money used to build it used to earn at the credit union. 2kWh per day added to the output of the solar array would also power the "protected" circuits of the backup system indefinitely. These are: deep well pump, refrigerator, freezer, boiler some lights and computers.

As soon as the solar system began to generate, the Whisper 200 produced nothing (only about ten kWh all summer). Unfortunately summer nights in Vermont are mostly whisper calm. The voltage rarely gets high enough to exceed the FMX-80's PV charging voltage. One milivolt less is enough to keep the turbine from being productive. It sat out there spinning every day like a beautiful lawn ornament but produced nothing. Measuring the voltage on one phase of the three phase wild ac coming in shows that it generally runs about 30V in light wind. If the batteries are charging at about 55 V the simple three phase bridge rectifier in the Whisper's controller needs to see at least 38V to produce any output. Our site is a low wind velocity site averaging ten mph or less (but we see storms of 80mph or more). The good news is that so far the turbine and tower have suffered no damage.

I have been told that the folks at Midnight Solar have the "Classic" controller almost ready and that it will solve the "low voltage" problem, but I got tired of waiting for commercial release.

I was ready to call the Whisper 200 a useless toy, but found that by bootstrapping around the controller with a polyphase voltage doubling bridge rectifier circuit, the turbine can start harvesting useful energy with as little as about 19V of input. The circuit is fairly complex 18 capacitors and 27 diodes (and some fuses for safety and to protect the turbine in case the circuit melts down,) but the parts are all cheap and the unit can be assembled from new parts for about $20. Unfortunately the current goes around the Whisper controller and the FLEXnetDC seems to discard the data, so I can't actually measure the increased output except with an ammeter (and I can see the battery voltage so I know the power level). But it isn't accumulated in kWh per day.

The bootstrap circuit starts to generate a few watts in very light wind and passes up to 75 Watts in wind that produced no output at all before. It also controls the wild spinning under no load (when the input is less than 40Vac). The 75W maximum levels off when the Whisper controller kicks in clamping the input voltage (at about .707 x the battery charging voltage). The bootstrapped current increases slightly with frequency as the total power output (through the Whisper controller) increases in strong winds. The functions of the Whisper controller seem to be perfectly normal up to full power. When the shunt load is engaged the input voltage drops below 20Vac so the bootstrap current is also terminated. Therefore the entire output of the turbine remains under the control of the Whisper controller so it can't overcharge the batteries.

With this circuit in place my satisfaction with the Whisper 200 on a short tower on a "light wind" site is much improved. The output is far from the total possible output at a better site. It will never "pay for itself" unless the utility rates triple (which could happen) but I am satisfied.

Re: opinions about wind generators

I have the W-200 connected directly to the battery ((through a breaker). The negative goes through a shunt to the common neg connection. The FLEXnetDC should record the kWh, but if it does I don't know how to read it.

The FM-80 input is for the PV array (also through GFI and appropriate breakers). Its neg goes through a different shunt to the common neg.

Re: opinions about wind generators

Sheldon wrote: »

Would you be willing to share your schematic?

Yes.
It is a fairly simple circuit. I seem to be having trouble attaching the image. to include it here. I would be happy to email a copy. The circuit was drawn with a program called DIA (Ubuntu Linux), and I have it exported as jpeg which can be opened with gimp. I am not very skilled with DIA so it is ugly. I also added 20k 1/4W resistors to shunt the "charged" capacitors, and a 4A series diode to prevent a phantom load when it is not generating. Those parts are not in the image.

Contact me at n1fmp@arrl.net.

So the image was attached. The image seems to be clipped. The curved jumpers on the right side should attach to a vertical + buss which is passed to the + termiinal through the series diode. The three phase ac connects to the right side The little connector circles seem to have been clipped. All capacitors are 180Mfd 100V, and the diodes are 1N4004. I put 2.5A circuit breakers on the AC side and a 5A DC breaker on the DC+. In 60mph+ 2 of the 2.5A breakers pop and disconnect the circuit (but there is no damage). I suppose higher current breakers could be used. (I don't mind resetting them and they very conservatively protect the circuit).

Ed