Wind Generator Regulator Help

[Walt]

The wind generator that I am trying to regulate is a 3-phase 1000 watt 120 volt unit. The generator is used to power a submersible pump. The problem is that the generator produces more power that the pump needs when the wind gets up above 15 mph or so. If the voltage rises above 300 volts the pumps electronics goes out ruining the pump motor. I installed a wind switch that controls a relay when the wind is greater than 15 mph that adds a 1000 watts of load to the line to help control the voltage.

What I think is needed is a PWM regulator that could sense when the voltage rises above 120 volts and begins to pulse the additional load to control the voltage. Is there such a device already and if so what is it called? Any other suggestions would be appreciated.

Walt

[Flux]

You seem to be on the right lines but there is not enough detail to fully understand your problem. I assume it is a brushless dc pump or some inverter drive to an ac motor.

No details of the wind turbine, does it furl or have some form of power limiting in high winds.

The pwm load should work as long as you can get rid of all the spikes. The voltage is high for most pwm controllers and it would seem extravagant to use something like a MX60 for such an application but it could possibly e programmed to do it.

Does your extra load keep the thing below 300v in all conditions, if there is no furling or other control it wouldn't take a lot of wind to double the power out and it may produce over 2kW . Don't know what the pump takes so I have no idea what % of full load your 1kW is.

I can only assume the thing was intended to be loaded by the pump under all conditions but you give no pump details. A centrifugal pump properly chosen and running at variable speed should load the thing. Restrictions in pipe size or wrong choice of pump would result in a limit on pump load at high speed.

I can't think of a commercial controller but the idea is ok with either pwm or even a linear dump regulator but you may have to build it.

You may in fact get away with no pwm, the wind switch had no chance but a static relay dumping your extra load on at 120v may be ok. The turbine will slow and the load come off, then it will pick up speed and the relay come on again. This is effectively a very low frequency pwm. It may work better with more than one stage.

This is nothing more than a heating load controller, not much details about it here but there has been a bit of discussion. Hugh Piggott has a heating controller circuit on his site using triacs and that may well work if you connect it to the ac terminals of the alternator.

Flux

[Walt]

Thanks Flux for your reply.

I will try to explain, the turbine is a Southwest Windpower H80 and the pump is a Grundfos SQFlex 11 gpm. The pump has a controller with rectifiers and a shut down switch. The pump only pulls 180 to 350 watts depending on how much back pressure there is on the discharge. When I purchased the system it was what Grundfos recommended. It is my understanding that they have had problems with this setup.

The load that is attached to the wind switch relay is two 500 watt heating elements and it does work. The problem with wind switch setup is that the wind speed varies between 10 to 20 mph most of the time and when the extra load comes on line the pump will shut down. After the pump shuts down it starts back up but only draws 10 to 20 watts for a few seconds, then the watts come back up to the 180 to 350 range.

I would like to have something that could monitor the voltage, when it started to rise above 120 volts then the device would bring the extra load on linearly. Something like the EnerMaxer regulator but it was for 12 to 36 volts DC.

Hope this helps, Walt

[Flux]

I can see you have lots of problems.

Your idea is basically ok, the problem is to find a simple way to carry it out.

I think your simplest option is to switch loads in stages so that each stage doesn't stall the turbine and stop the pump. If you work at something like 120v for the first step and add perhaps 200W of load then you may be able to add 500W at perhaps 150v and then another 1kW at perhaps 180v. You say your controller dies at about 300v so 180 should be safe.

The snag as far as I can see is switching these load resistors on dc but mosfets should do it. I would use 3 op amps or comparators driving mosfet drivers. I am fairly sure these things will switch on and off without any need for deliberate pwm control.

You may have to introduce a little bit of dead band into each comparator.

If you can't manage to build something then look for a hydro controller, they have similar problems regulating volts and frequency but they may switch on the ac side. You may be able to do that with static relays but it may be an idea to try to keep the phases balanced at least when you are near full turbine output. The first stage could be a single phase load without bothering things too much. You may get away with loading one phase, 2 phases and finally 3 phases. It all depends on whether you can get to the ac side of your rectifier.

Flux

[Walt]

Flux,

The load that is on there now is on the AC side of the rectifiers.

Walt

[Flux]

You may be able to adapt the circuit on Hugh Piggot's web site for the heater controller.

Flux

[scottsAI]

Walt,

Goal is to load wind turbine such that the output does not exceed 180vac.

3 phase requires 3 heaters and 3 controllers.

Fortunately the controllers are simple:

http://www.tpub.com/neets/book7/26e.htm

Figure 3-25B.

Adjust the ratio of the resistors so the triac does not come on until the voltage is above 120vac.

As the wind picks up the output voltage will increase turning on the Triac a little sooner loading the generator cycle by cycle. Loaded turbine should slow down, controlling (limiting) the output.

If that does not work, then using a slightly more complex circuit will be needed as used in light dimmers giving a more proportional loading. Not tried this before.

Use triac rated for twice the voltage you expect it to see. CYA. (600v). For DIY same for current. For large production I use different numbers based on cost/application.

Test the circuit with a variac, need 240v version. The circuit loads the generator for half a cycle. Adjust each phase a few volts different to ramp the load. Hugh's pages warns may cause vibrations in wind turbine. YMMV.

The heaters must be larger than the worst case output of the wind generator.

Working with high voltages use proper precautions.

Have fun,

Scott.

[scoraigwind]

One option is to feed a rectified output from the turbine to an LDR wind machine controller from http://www.solarconverters.com/product_frame.html

You would need capacitors.

This clamps the maximum DC voltage.  There are several models for different battery voltages.  note that the actual clamping voltage is higher than the nominal.  

      12 V @ 100 Amps

      24 V @ 60 Amps

      48 V @ 30 Amps

      96V @ 15 Amps

      180V @ 10 Amps

      360 V @ 5 Amps

I am not sure if your 300 is rms or what.  If so then the 360 VDC might be good for you.

[Walt]

Flux,

I looked at Hugh's controller and I think this is the way to go. The only thing that has me confused is the transformer. What should the primary and secondary voltages be if the generator voltage is between zero and 300+ volts? Will a 120 volt primary with a 5 volt secondary work? The 2917 tach chip will only take a maximum voltage of 28 volts if I am understanding the spec sheet.

Walt

[Flux]

The 2917 works from about 200mv upwards and without protection is limited to 28v. With a limit resistor and a pair of back to back diodes it will be safe.

Watch the transformer, it's not volts that matters it's volts/cycle. A transformer rated at 120v at 60Hz will only handle 60v at 30 Hz.

You need to know your machine maximum voltage and frequency. I don't know the alternator but I suspect that the top frequency will not be very high. You may need a 415v or higher transformer to handle 200v if the frequency is low. Choose the ratio to give something like 12v for the maximum input volts.

Don't exceed the volts/cycle limit on the primary of the transformer or you will cook it. Finding a suitable transformer may be tricky, high voltage ones are not common. If you can get at the star point of the alternator then you can nearly halve the voltage requirements. It is sort of possible to add a series limit resistor in the transformer primary circuit to limit current when the core saturates but the waveform becomes diabolical although in theory the 2917 shouldn't mind.

Another alternative is a series resistor and a pair of back to back zeners, this will give you a clamped square wave which you can isolate with a transformer. These tricks are ok but you need to know what you are doing. Opto isolators would also work with this clipped square wave but for simplicity check your frequency and see if you can find a suitable transformer.

Flux

[dnix71]

The problem is the turbine design. According to this website, the furl mechanism is designed to hold the turbine at max power no matter how fast the wind, rather than have it drop off.

http://www.etaengineering.com/windpower/w200.shtml

Maybe altering the furl would limit the peak voltage to something safe.

[scoraigwind]

the purpose of the transformer is to isolate the AC circuit from the DC circuit.

[Flux]

No chance of doing anything there. There are more problems in the turbine area that I don't want to get involved with. The dump controller in some form is the only way.

Flux

[bracken]

Simplest method you need two resistors, zener, mosfet, and thick coil of wire. Make a voltage divider out of the resistors down to manageable levels of play around 10V at 170 peak or what ever you want you max voltage to be. Get a 12V zener diode and hook it up to the out put of the voltage divider and the gate of the mosfet, when the voltage from the voltage divider get the break down voltage of zener diode the the mosfet opens and shorts your current into the coil which you have placed in the water you pumping (no heat problem). This will effectively "Pulse Width" your power and keep your voltage where you want it.

http://en.wikipedia.org/wiki/Voltage_divider

http://en.wikipedia.org/wiki/Zener_diode

Small orders can be purchased from jameco.com

good luck

Bracken