DIY inverter generator

[glort]

You have encouraged me! I have not bothered with drying the veg oil for the boiler as it is not really necessary for a burner but I will have to build a system like in your video. Thanks!

No, I wouldn't bother with drying oil fo burner use either but I can tell you the burners do work better with dry oil. Not enough to be worth it in my book as long as the oil has no free water in the bottom of the tank.

Don't know what C2C configuration is but sounds like that is what you did to get single phase out of a 3 phase motor. 

2C is basicaly capacitance, 2x capacitance.  The way it works is for say a 5 Kw motor you would have 20Uf  between legs 1-2. between 2-3 you would have 2x 20 Up caps in parallel to give 40 Up or a single 40 Up cap.  Between legs 3-1 you have no caps.
They basically work as an electric delay between the phases and eliminate the 120o separation of the phases lining them all up back to a single phase.

Are the capacitors on your induction generator for smoothing or for excitation starting?

C2c is both phase alignment and maintaining the excitation of the non powered windings in the motor. In a generator the rotor is powered. In a motor it is not so the caps keep some power in them to maintain the magnetic Field.

I don't understand how your induction generator locks the frequency when you back-feed to the grid.  I don't have any intention of doing that in this system, just interested. 

3 phase rotates in sequence.  The mains frequency locks to each winding and stays locked. There is no slip like a generator.

This system is in fact far and away the best way of going about your project. It eliminates many of the potential problems and simplifies the setup.

[glort]

I doubt BC Hydro will allow a direct backfeed from an induction generator such as this because of anti-islanding and safety rules.

An induction motor set up as a direct generator has automatic anti islanding.  The motor cannot maintain excitation with a load and no caps. Not possible.  The mains provides the excitation.

If your electric co won't accept it direct, I'd be looking for some sort of controller hey will approve so they will.  The thing is an induction motor is impossible to keep generating without the grid unlike a proper generator.

If an inverter can ani island there must be some device that can do the same  when supplied  with an external power source.

[bryanb]

I only have single phase to my site.  Would a single phase induction motor be better for an induction generator or a C2C configured 3 phase motor?

[glort]

You would probably not find a single Find a single phase motor over 2.5 Hp which would not give you much generation. You also have to modify single phase motors because they have a starter switch/ cap which has to be bypassed.  I have used them as is but only for play purposes.

-MY- rule of thumb is to have a motor double size motor than what you want to generate. Eg, for 5 Kw Back feed use a 10 kw Motor.  Rule of thumb for the Diesel engine is 10 HORSEPOWER for a 5 KW generator.

If you want to do 5 Kw generation, then you ( as far as I have seen here) not find a single phase 10 kw single phase motor.  If you are thinking of a car size engine then you would be wasting your time with anything smaller and I'd be going as large as the wiring will take.  You can control output by how fast you turn the induction motor. You could have -say- a 20 Kw Motor and slow it down a bit and ony generate 5 Kw or you could speed it up and generate 10. Unlike a generator, when direct coupled to the mains the frequency is locked and the speed only controls output.

[mike90045]

There are lots of pages on the interwebs about using induction motors as a generator.   They all need to have some fine tuning of a couple caps to keep them stable, as loads change, you change caps.  Fine for fixed loads of battery charging, but tough to manage with blow dryers and microwave ovens.   But as you oversize the induction motor, you get more stability from them.

[mobile_bob]

gasp!  (choking back the tears)  our baby is still alive! 

good to see some life around here.

on the topic, from what i remember, single phase motors can be used, but iirc you
figure on about 10% of name plate capacity as a generator, that is for stable output

so if a motor is rated at 1000 watts as a motor, figure on 100 watts as a generator, that is stable output

of course as stated, perhaps under a fixed load scheme, you could get more, but the voltage will spike higher under
no load conditions.

interesting thing, the induction motor to generator thing

bob g

[glort]

One trick I have seen and tried with the IMAGs is to wire a cap to each load you want to drive. that way each load compensates for itself and the problem of loosing excitation with load is greatly reduced. Each load compensates for itself.

There are IMAG controllers. They work by fully loading the motor and then Diverting the power needed to the load.
The punjabs do a lot of work with these things as obviously they are cheap ( the motors as well as the people) and that is a big incentive.

The stability concerns ONLY apply when the motor is being used as a stand alone generator. When grid connected the things are rock solid and a set and forget type proposition.

Hopefully I might be able to pick up the 2 30Kw units i found this weekend. Being the size they are it likley they are slow speed motors, maybe 960 RPM so that will be a good match for one of my little China horozontals as far as gearing with the pulley sizes go.  Engine is only 5HP so won't be able to drive the motors near what I can get out of them but fine to use to set up and test with.
I have a 30 Hp 2 Cyl Ruggerini engine that will be a better match for higher outputs and backfeeding.  Going to have to make a PTO plate for the flywheel with that with a stub shaft and pulley.  Should be able to drive that to the full 15KW output in standalone mode.

[bryanb]

update:  using a wind inverter as opposed to a solar inverter will give access to the mppt function allowing me to eliminate the generator governor hunting issue.  Unfortunately, finding a CERTIFIED wind inverter is proving difficult.  The SMA "Windy boy" and the Ginlong products would have worked well but they are no longer in production and I have not been able to find an equivalent one or a used one.
I have found a smaller (2000W), but stackable, unit out of China, but doubt it is certified for Canada. It is intriguing because it takes wild 3 phase AC as an input.  I am waiting to hear back regarding the certifications.  Here is a link:  
https://www.aliexpress.com/item/LCD-Display-Solar-Grid-Tie-Inverter-Inversor-2000W-With-Internal-Limiter-45V-90VDC-Input-to-220V/32837566016.html?spm=a2g0s.13010208.99999999.259.52fe3c00tAtotG

Any comments about this one or does anyone know of a used SMA or Ginlong unit for sale? (in the neighbourhood of 6 to 10 kW)

[David Baillie]

Oh boy... not to pee on your parade but net metering in BC is limited to "green" generation as of the last time I looked. I know green is a moving target but right off the bat grid tied veg oil using repurposed 3 phase motors is out... legally. I'm all for a little guerilla generation but most areas have gone to digital meters so the days of spinning it backwards on the sly are over. Unless you have a solar array in the background or wind turbine hydro will simply not grid tie you. There are plenty of options. The most straight forward one I can think of is to offset your usage with a dedicated load panel and a small battery inverter setup. Generate however you want feed into the bank greater then the daily usage... costs saved. With a simple generator sub panel you can switch over to grid on days you are not running the system. The industry refers to grid connected systems without feed back as grid zero systems. Very flexible as to generation sources with mama grid in the background to save your bacon if needed. Financially... well the grid price will always be the cheapest so it has to be about cool factor...

[bryanb]

net metering in BC is limited to "green" generation
The industry refers to grid connected systems without feed back as grid zero systems.

Yes, I already have BC Hydro approval on the "green" veg oil generator setup.  I didn't think the 3 phase induction motor would be a certified setup but was interested as a standalone generation. 
The only detail I am having a problem with now is the inverter.  A solar inverter mppt does not play well with a generator governor but a wind inverter mppt does.  Unfortunately there does not appear to be anyone manufacturing certified ones any more.  SMA, Power-One/ABB, and Ginlong/Solis, used to make grid tie certified wind models but have discontinued them.

A grid zero sounds good but is not appropriate for this application.

I am trying to find a used/old stock certified wind inverter so if you hear of anyone who is selling, let me know ...

[glort]

A solar inverter mppt does not play well with a generator governor but a wind inverter mppt does. 

Can You explain why?
I can't think of any difference in how the 2 would work?
The wind would probably accept AC and there would I think be more capacitance to absorb the more erratic nature of the wind input but other than that....??

[David Baillie]

net metering in BC is limited to "green" generation
The industry refers to grid connected systems without feed back as grid zero systems.

Yes, I already have BC Hydro approval on the "green" veg oil generator setup.  I didn't think the 3 phase induction motor would be a certified setup but was interested as a standalone generation. 
The only detail I am having a problem with now is the inverter.  A solar inverter mppt does not play well with a generator governor but a wind inverter mppt does.  Unfortunately there does not appear to be anyone manufacturing certified ones any more.  SMA, Power-One/ABB, and Ginlong/Solis, used to make grid tie certified wind models but have discontinued them.

A grid zero sounds good but is not appropriate for this application.

I am trying to find a used/old stock certified wind inverter so if you hear of anyone who is selling, let me know ...

that is extremely progressive on their part... give me a moment I'm confused!.  In terms of grid connected wind inverters I would try contacting farm energy in ontario. Chris Myers rebuilds inverters and turbines and has a large inventory of toys. I dont know if he can help you but if anyone can...   http://www.farmenergyinc.ca
Cheers,  David

[bryanb]

A solar inverter mppt does not play well with a generator governor but a wind inverter mppt does. 

Can You explain why?
I can't think of any difference in how the 2 would work?
The wind would probably accept AC and there would I think be more capacitance to absorb the more erratic nature of the wind input but other than that....??

A wind inverter calculates the current draw based on the generator RPM as opposed to a solar inverter which constantly adjusts the current draw by loading until there is a voltage drop.
The wind inverter uses a current draw table and develops a curve based on that table.  So at a certain RPM it will draw a certain current.  That way there is no "hunting".

[mike90045]

The Midnight Cla$$ic Controller has programmable MPPT setpoints, but it's a charge controller, not inverter.   

[LowGear]

My understanding of the SMA Sunnyboy (grid tie solar inverter) and Windyboy (grid tie wind turbine inverter) can be programmed back and forth.  I'm not sure about the later models.