I am in the process of putting together an 8 kW micro-cogenerator. It is only a single phase 120/240 generator so once the 240 is rectified, I should have ~300VDC which will go into the inverter. The inverter will be a solar string inverter accepting 150 - 600 VDC.
The purpose of this setup is NOT for electricity! It is for heat. The generator RPM will be controlled by the heat demand of my greenhouse. The generated electricity will just be a bonus.
I believe I have most of the details worked out except for ...
as the RPM varies (and thus the voltage), the voltage regulator will not be happy.
Do I just disconnect the regulator? What happens when you run a generator without a Voltage Regulator? The inverter doesn't care what the voltage is, because it has MPPT and adjusts accordingly.
Anyone have experience with this???
Thanks for any and all advice.
So I finally found some proper information on voltage regulators. My understanding at this point is that I can pull out the AVR and excite the field with a fixed DC voltage similar to what they call "flashing" when testing the generator. I don't know what voltage would be appropriate so I will start with 9vdc as mentioned in the "flashing" instructions and go up from there while monitoring the generator output.
I will post back my results when I get a chance to try it ...
Wish me luck!
Sounds pretty edgie to me but I read the instruction manual once in a while before breaking something. I'm thinking heavy rubber soles might be the smart first step.
And Yes! Good Luck.
The inverter will not be happy with varying RPM/Voltage and the DC rectifier will create lumpy DC from single phase AC
Why not figure what the raw/wild AC voltage is and use that as your heating source and not try to rectify and reinvert ? Use a fixes 240V heater element and reduce engine speed (voltage & Hz) as you need less heat ?
Quote from: mike90045 on January 23, 2019, 10:12:42 AM
The inverter will not be happy with varying RPM/Voltage and the DC rectifier will create lumpy DC from single phase AC
Why not figure what the raw/wild AC voltage is and use that as your heating source and not try to rectify and reinvert ? Use a fixes 240V heater element and reduce engine speed (voltage & Hz) as you need less heat ?
I will be using a solar string inverter which is designed for a variable input of between 100VDC to 600 VDC
The lumpy DC from the single phase will be smoothed with adequately sized capacitors. I am on the hunt for a 3 phase genset though ...
That is a really good idea to use the raw/wild AC in a heating element, didn't think of that. But the purpose of this system though, is not to use the electricity for heat but to use the waste engine and exhaust heat. The electricity will be grid-tied and used for other than heating uses with any excess being sold to the grid.
thanks for the input and idea though!
Be aware that trying to slam huge amounts of power directly into capacitors as is done for small power supplies is going to give you crap power factor, meaning fuses/breakers popping or generator windings fried. Instead, use a choke filter, around 5 mH, as the first element. That will restore your PF and smooth out the current waveform. It's going to be a monster, though. Gapped toroidal transformer cores make nice chokes for this purpose and any of the custom transformer shops can make one for you. Hamilton makes big power E-I cored chokes of this sort also, and you can occasionally find them used on ebay.
Using ICE to generate heat is a lot of moving parts to maintain for what could be done more efficiently and with far fewer parts with a good burner, and some like the Babington can burn any kind of oil. You aren't the first to attempt this, even on this forum, but the operating cost of using an engine as a heater is not going to work out well economically. The exhaust heat is about 1/3 of the total and is a PITA to collect due to service/maintenance issues.
A fun project though, certainly.
Quote from: BruceM on January 23, 2019, 10:50:35 PM
Be aware that trying to slam huge amounts of power directly into capacitors as is done for small power supplies is going to give you crap power factor, meaning fuses/breakers popping or generator windings fried. Instead, use a choke filter, around 5 mH, as the first element. That will restore your PF and smooth out the current waveform. It's going to be a monster, though. Gapped toroidal transformer cores make nice chokes for this purpose and any of the custom transformer shops can make one for you. Hamilton makes big power E-I cored chokes of this sort also, and you can occasionally find them used on ebay.
Using ICE to generate heat is a lot of moving parts to maintain for what could be done more efficiently and with far fewer parts with a good burner, and some like the Babington can burn any kind of oil. You aren't the first to attempt this, even on this forum, but the operating cost of using an engine as a heater is not going to work out well economically. The exhaust heat is about 1/3 of the total and is a PITA to collect due to service/maintenance issues.
Thanks for the choke filter info! I will do some more research ... Do you have any recommendations on how to size the choke and I assume, some capacitors?
I will be using Waste Vegetable Oil for the fuel, so fuel cost will be minimal (just collecting / processing costs). There will be maintenance and service costs associated with the heat exchanger which I have designed and budgeted for.
By the way, I will be using a waste oil burner (boiler) as my backup.
Bryan
Been there, done that, have the Vids on YT.
The problem with using a GTI is the MPPT will always be trying to find the sweet spot loading up and unloading the engine. Which will make the engine governor open up and then close down and the 2 just see saw back and forward.
The only way I know to minimize this is to run the inverter flat out with an engine considerably larger than it needs so it can drive ( overdrive) the inverter all the time.
IF you are back feeding it -may- be possible to eliminate the Governor and set the engine speed so it can't move. This would depend on the inverter being driven flat out and the circuit it was connected to also being pretty stable, IE, Heavy wire back to the board rather than on a normal circuit with intermittent loads kicking in and out. Again, you'd want an engine with plenty of head capacity.
Capacitors are going to make zero difference. Been down that road too. Unless you can access a broom cupboard full of them, they won't have the capacity to provide the smoothing needed.
I'm not sure if your motivation for the project is Fun or profit but if it is profit, let me tell you you are going down the wrong track. you CANNOT make power as cheap as you can buy it from the grid. Trust me, I have been mucking round with veg oil and running everything I can on it for 16 years now but it takes more than free fuel to make your own generation worth while. your investment in the equipment alone and the return you get for what you spend will never be repaid.
You mention selling to the grid. If you are going to do this legitimately which you can't because they won't accept it, you are kidding yourself if you think you can make money at 8 or 11C Kwh which is what they will pay, .20 if you are lucky but they won't be buying it off you generated that way.
Maybe you have a solar system and are going to do a dodgy by back feeding it into that. My moral opinion on that sort of shady practice is ..... Good on you!
Problem is it won't work. it's going to cost you.
Maybe you are going to do something " illegal" Like spinning your power meter backwards. If you need any advise on that let me know! :0)
Thing is on both accounts an engine is not the way to go.
Blowing my own trumpet there is not a lot of people that know more about running engines of free fuel than me and even though I have a shed full of engines, I don't bother to use them to back feed. It is not worth it.
What I do have is a virtual Solar farm with almost 20 Kw ( and adding) worth of panels.
THAT IS worth it!
I am also just a little knowledgeable in burning waste oil. built loads of the things and am presently modifying a 100Kw spa heater to heat the house this winter. Still NO engine. There are too many problems if you think it through as well as impracticality's.
I use second hand panels to make power that spins my meters backwards. in winter when teh solar falls through the floor I will use the oil burning heater for warmth instead of the Ducted AC or at least to supplement it. Don't expect Mrs to go light the thing at 6am on a winters morning, she can hit the air but at night she will be able to come home to a toasty house thanks to the burner.
Engines make noise, you have to attend to them, you have to find somewhere to put them that's close enough to the house not to loose all the heat you get but not too close they drive you nuts or make the place look like a scrapyard. Burner is much easier to locate and easier to attend to.
Mine will heat water which will be circulated through a radiator with fans I'll probably mount in a window to start with and push the air into the house like that.
I'll incorporate a 2 stage thermostat and have the burner stepped between idle and heat. Easy to have a fuel pump for the oil and a blower for air on a Pwm controller and switched with a DPDT relay between the modes. I am also thinking to have a Dump radiator before the spa heater so if things get too hot fans will come on that and pull the excess heat. I will have a non sealed system with a header tank on the roof probably so the thing will never really be able to boil dry and there will never be any pressure in the system.
If you use an engine on veg you WILL have to run a water injection system. Another thing I have done a lot with. If you do not the exhaust will coat the inside of any HE in hours or less and your efficiency will fall through the floor. you will also probably have to clean the thing almost daily to stop that buildup clogging the HE all together. Hot Diesel exhaust condensing in a Cold HE is NOT a good Idea my friend. Honestly i'm not even sure WI would be able to offset the problem but you sure as hell won't be able to do it without that as a minimum. You may need to inject water behind the exhaust outlet of the engine as well. WI will also be a very good safety factor in Running Veg in any diesel. I wouldn't run an engine without it.
If this is a practical exercise, I would strongly suggest a re think.
If it's for fun, well nothing much matters other than learning.
Quote from: glort on January 24, 2019, 03:25:57 AM
1) Been there, done that, have the Vids on YT.
2) The problem with using a GTI is the MPPT will always be trying to find the sweet spot loading up and unloading the engine. Which will make the engine governor open up and then close down and the 2 just see saw back and forward.
3) Capacitors are going to make zero difference. Been down that road too. Unless you can access a broom cupboard full of them, they won't have the capacity to provide the smoothing needed.
4) you CANNOT make power as cheap as you can buy it from the grid.
5) I have been mucking round with veg oil and running everything I can on it for 16 years now but it takes more than free fuel to make your own generation worth while. your investment in the equipment alone and the return you get for what you spend will never be repaid.
6) You mention selling to the grid. If you are going to do this legitimately which you can't because they won't accept it, you are kidding yourself if you think you can make money at 8 or 11C Kwh which is what they will pay, .20 if you are lucky but they won't be buying it off you generated that way.
7) Maybe you are going to do something " illegal" Like spinning your power meter backwards.
8) Blowing my own trumpet there is not a lot of people that know more about running engines of free fuel than me
9) I am also just a little knowledgeable in burning waste oil. built loads of the things and am presently modifying a 100Kw spa heater to heat the house this winter.
10) I use second hand panels to make power that spins my meters backwards.
11) If you use an engine on veg you WILL have to run a water injection system.
1) Would love to see your videos! Can you share a link?
2) The generator will NOT be throttle controlled by load. The throttle will be controlled by the boiler water temperature, so in other words, the heat demand. So there should not be any feedback loop or any see-saw.
3) I am investigating the choke filter idea that BruceM suggested but if that doesn't work out I may look at getting a 3 phase generator instead.
4) I agree with you about not being able to generate power as cheaply as I can buy it from hydro, but that is not the main function of this installation. The main function is as a heater, and the electricity is a byproduct. Granted, an engine is a lot of moving parts and maintenance compared to a boiler, but if you consider the heat output and the electricity, it starts to look better.
5) What motors do you run with veg oil? And what conversion systems did you use? Do you have videos of those as well? I have noticed the newer engines (tdi) burn much cleaner with less soot and am hoping the heat exchanger will not carbon up THAT fast. We will have to see ...
6) As to the legitimacy of Grid-tie, I already have approval from BC Hydro for the Veg Oil Generator but all I can do is offset my yearly hydro bill. I will not be able to be a net producer over a full year. I have sized the generator to deliver my yearly capacity over the heating season (winter).
7) So I will be spinning my meter backwards during the heating season and building up credits to be used in the summer when the generator is not running. Not illegal.
8) Would love to know more about the veg oil fuel conversions you have done! Links?
9) The spa heater project sound awesome! What type of burner are you going to use?
10) Where did you get second hand solar panels? I am interested!
11) I am also very interested in the water injection systems you used and the effect on the system. Do you have links or could you elaborate?
Thanks so much for the feedback!!
Bryan
Using a big choke as the first stage of filtering (BEFORE capacitor) requires what is known as ''critical inductance''. You can google that and find the equation. Other than that, you just need a choke rated for at least your max current. 20,000 uF and 5 mH will probably be adequate.
3 phase would be vastly better for making DC, and would require a smaller choke and less capacitance. Depending on the inverter, nothing but a 3 phase rectifier may be needed (6 diodes).
I've read about the cyclic loading from MPPT inverters which Glort refers too, but have no first hand experience to be able to suggest solutions beyond the one he suggests which effectively bypasses any MPPT hunting. The problem he reports I've read of several times from different sources.
Glort will have some words with you when I list this about BC power rates:
Under the Residential Conservation Rate, customers pay 8.58 cents per kWh for the first 1,350 kWh they use over an average two-month billing period. Above that amount, customers pay 12.87 cents per kWh for the balance of the electricity used during the billing period.
Canadians have it pretty soft if BC Hydro lets you store up back feed credits for use 6 months later! They must be zinging you with a ferocious monthly fee or I can't see how they can manage. Otherwise you have a free battery service, in effect. Sweet for you if true.
Quote from: bryanb on January 24, 2019, 04:00:42 PM
1) Would love to see your videos! Can you share a link?
https://www.youtube.com/watch?v=HUE1RQRAXlg
This was Running a 3 Phase Induction motor as a generator by adding caps in a C2C configuration.
I was going to suggest this in my last post but forgot. I agree with Bruce, 3 phase is the way to go. Induction motors are a lot cheaper and easier to find ( here at least) than gen heads. If you don't have the genny already, I'd be looking at that.
This is another vid using the induction Genny Direct on a load.
https://www.youtube.com/watch?v=tqy4nJ4cZ5A
The BIG advantage in this situation with a 3 phase induction motor over a genny is you DON'T need the GTI. Hook the 3 phase to the mains power, spin it up and it will be frequency locked and once you get over about 10% rated motor speed, it will start pumping power back to the grid. Direct connection, no inverter, capacitors or anything else and you will have a stable load that won't hunt the engine.
The only thing will be you have to keep the engine speed above the nameplate rating of the motor which isn't hard if you gear it so " idle" is still producing a little power. The faster you rev the engine the more power it will make.
Quote2) The generator will NOT be throttle controlled by load. The throttle will be controlled by the boiler water temperature, so in other words, the heat demand. So there should not be any feedback loop or any see-saw.
Sitting here doing the mental arithmetic on how this will play out, I guarantee there will be HEAPS of see sawing of the engine.
The GTI will ramp up and down it's demands trying to find the sweet spot where it makes the best power. The fluctuating load on the engine WILL cause it to ramp up and down. It can't do anything else. you are going to set it to heat demand and the GTI will be trying to get the power it wants. Anything below max capacity it will be looking for more and ramping it's demand up and down which will be loading and unloading the engine and it will see saw.
I won't not go this way at all for your purposes. Direct tie a 3 phase motor, overdrive it and you are there. that simple and problem free.
Quoteinvestigating the choke filter idea that BruceM suggested but if that doesn't work out I may look at getting a 3 phase generator instead.
As mentioned, just go for a 3 phase induction motor. Cheap and easy to find loads of the things. I found 3x 30Kw units couple of weeks ago. They will give me an easy 15Kw or 5 Kw per phase. more than enough to drive my big 3 phase air con.
The 3 phase can be setup in a C2C configuration to give single phase as well. I think that is what I did on the 2nd Vid.
Quote4) The main function is as a heater, and the electricity is a byproduct.
Then I'd just use a heater. :0)
Quote5) What motors do you run with veg oil? And what conversion systems did you use? Quote
I run mechanicaly injected diesels. Vehicles, small engines. All the same.
NO conversion Needed. Don't even get me started on that! Conversions with heating the oil are all complete and utter bullshit other than for the purpose of keeping the oil liquid. All the garbage about having the oil hot so it sprays better through the injector is complete and utter crap and an insult to a thinking persons intelligence. I have run Vehicles for over 10 Years with NO heating of the fuel at all save for sitting the metal filter on the exhaust manifold to put a bit of warmth in teh fuel to dissolve any fats that may have dropped out.
There is a LOT of crap about running veg oil. most of it is by people who never got thier hands dirty doing a conversion and just did what the guy before them did who followed somone else who copied the guy before who.... and not one of them stopped to think why the heck they were doing any of it, how it applied to their situation and what the purpose of what they were doing was. The blind leading the dumb and everyone insisting that is how it needs to be with not one single person thinking about it let alone ever doing some actual testing.
All you need to do is filter and DRY the oil and put it in the tank. If it's cold add 5-10% ULP and that's it. If the fuel flows and you have processed it properly, that is all that's needed. If you are where it snows, keep the oil at or above about 30oC to keep the fats melted and you are there. In stationary use there should be no problem getting the oil fat free to start with as the engine and the oil should be at the same temp all the time.
QuoteDo you have videos of those as well?
Not many engines on my chanel but there are about 80 boring Vids of me being an idiot so have a look through the channel.
QuoteI have noticed the newer engines (tdi) burn much cleaner
This worries me.
How much experience and knowledge do you have of Running veg oil? It seems not as much as might be advantageous in this project.
I have been doing it 16 years+ and I do things others wouldn't think of and make it work but running a TDI engine on veg is something I wouldn't even dream of!
The Fuel systems are absolutely the worst to use with Veg and are trouble and finicky enough on Diesel. The VW and Toymota engines also have big problems with EGR recirculation that blocks the inlet manifolds and even can stuff the valves. Using veg only makes that 100X worse. You would probably get past that with WI but it's sure not going to make the weak fuel systems any more resilient.
I would Highly recommend you have a serious rethink about going near a TDI with Veg oil. I wouldn't and I'm wreckless by most pedantic veg oil user's standards.
Quote6) As to the legitimacy of Grid-tie, I already have approval from BC Hydro for the Veg Oil Generator but all I can do is offset my yearly hydro bill.
Lucky you!
Wish we had that sort of ability here. Could only dream of such things.
I'm going to do another swifty and carry over my autum accumulation to winter by locking my meter box at read time. They will send me an estimated bill and probably a whining letter about having access to the box but it will allow me to build up some generation credit in advance.
Quote7) So I will be spinning my meter backwards during the heating season and building up credits to be used in the summer when the generator is not running. Not illegal.
I do it the other way round, Credits with stronger solar in summer/ spring / Autum and struggle by in winter. Trying to hedge my bets as above this winter though. Been 40C+ here for the last week. winter seems unimaginable right now!
Quote8) Would love to know more about the veg oil fuel conversions you have done! Links?
No links, no conversions to link! :0) hae a look though my channel for some oil processing Vids. that's the important bit. Conversions are complete and utter bullshit. If the engine is fit to run on veg, it does not need a lot of He's and change over valves and all that crap. Been there, done that, life was much better when I woke up and threw it all away. the only conversion needed is the fuel with a bit of blending. Use petrol NOT diesel. Petrol thins the oil and makes the ignition timing of the fuel much closer to that of Diesel. Blending with diesel just makes thick Diesel. you can't effectively thin something starting at the point you want to finish at. 10, maybe 15% ULP if it's snowing cold is all you need to do to convert an engine and make sure the fuel is properly filtered and DRY.
There are Vids on my channel of how to dry your oil which is mega important and about 99% over looked.
Quote9) The spa heater project sound awesome! What type of burner are you going to use?
Forced air type as I favour on my channel. Probably go for a Horizontal slit type to better replicate the gas burners that I pulled out and spread the heat a bit instead of having it like a concentrated blow torch. I have also been eyeing off the original gas burner and thinking I could probably sit an extinguisher type bottle over the burners and use it like a vaporiser to direct the oil vapor into the original burner. Start the thing on gas, add oil, off we go. Would just have to play with the jetting perhaps but I don't think so. Something I might look at.
Quote10) Where did you get second hand solar panels? I am interested!
Second hand site called Gumtree mainly. I believe it is similar to your Craigslist. Fleabay would be another source. there seems a lot more here than in the states but I don't know what the availability in Canada is like. I don't pay more than $100 Kw for panels here and usually less.
Quote11) I am also very interested in the water injection systems you used and the effect on the system. Do you have links or could you elaborate?
Don't think I put up a vid on the WI. I remember filming at least one but Might have lost or not published it.
For stationary use all you need is a constant infusion of water into the engine intake. You do NOT need mega fine mists, ultra high pressure pumps and other expense and complication that you will be brainwashed with on the net. A steady drip is all that is required. Many different ways to go about that, all you need to do is make sure the water stops when the engine does. Could be as simple as a relay that activates a small pump or a solenoid valve and shuts off when teh engine stops as in powered from an alternator.
Amount of water is not critical and don't get concerned about hydrolocking the thing. You'll know well in advance if there is too much water by the engine stumbling and steaming out the exhaust a LONG time before she locks. Never tried it but I highly suspect unless one dumped a load of water in the intatake it would be near impossible to keep an engine running with a stream of water and get it to compression lock on water. The fire would go out way before.
As a rough guide i'd say 300 to 500Ml would all that would be needed to keep an engine deposit free. For vehicle engines I have found 300 ML a MINUTE max delivery on a 3 Litre engine works well. That's not constant though, I set that up when the engines are under at least 50% load. I have run a lot more than that for performance purposes but for cleaning, can't clean whats not dirty so that is well adequate.
For stationary use, regular feed is better and does not need a lot, just enough to keep deposits building up. Mind you, if water is close and easy to full a good size tank, A litre an hour wouldn't be bad either.
QuoteThanks so much for the feedback!!
You're welcome. Give me some insight as to what your veg oil experience is. A lot will be riding on your knowledge with that for the success of this project.
Very helpful input. Thanks!
BC Hydro monthly fee is only $6. Yes, that is cheap for the use of the grid to build credits for the other half of the year.
I have been only mucking around with veg oil for 4 years and only in a heating system. I have diesel vehicles but have not used veg oil in them yet. 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!
It also turns out that I have a couple of larger 3 phase induction motors kicking around. I am definitely going to check this out! 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. Could be useful for other projects. I will do some more research.
Are the capacitors on your induction generator for smoothing or for excitation starting?
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.
Cool videos by the way ....
The induction generator is self syncing when doing grid backfeed, you just increase rpm slightly above operating rpm and watch the backfeed current as you pour on the power. Much cleaner and simpler setup for you, better efficiency. No load specific capacitors needed for this application, and it automatically stops when power shuts off.
In my case, generating to feed the inverter, or as a standalone generator, will an induction geny self excite?
I doubt BC Hydro will allow a direct backfeed from an induction generator such as this because of anti-islanding and safety rules. But as a standalone backup generator, I am excited! (pun intended)
Quote from: bryanb on January 25, 2019, 10:21:08 PMYou 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.
QuoteDon'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.
QuoteAre 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.
QuoteI 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.
Quote from: bryanb on January 26, 2019, 06:10:13 PM
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.
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?
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.
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.
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
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.
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)
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...
Quote from: David Baillie on January 31, 2019, 07:03:41 PM
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 ...
Quote from: bryanb on January 31, 2019, 10:38:36 PM
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....??
Quote from: bryanb on January 31, 2019, 10:38:36 PM
Quote from: David Baillie on January 31, 2019, 07:03:41 PM
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
Quote from: glort on February 01, 2019, 01:15:27 AM
Quote from: bryanb on January 31, 2019, 10:38:36 PM
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".
The Midnight Cla$$ic Controller has programmable MPPT setpoints, but it's a charge controller, not inverter.
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.
Quote from: LowGear on February 02, 2019, 03:24:56 PM
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.
Yes, the Windyboy is ideal for my purpose! Unfortunately all three of the companies that produced Canadian Certified wind inverters: SMA (windyboy), Ginlong, and the other company (can't remember the name) have discontinued production of wind inverters. If you know of any used ones that are available, please let me know!
My son just gave me the idea of installing a current regulator between the generator and the inverter. The heat requirement (thermostat) would control the generator RPM and the current regulator at the same time. This would stop the inverter MPPT from constantly "testing" the load and messing with the engine governor. Not ideal but do-able? Anyone have any input on the feasibility of an adjustable current regulator? How could it be varied?
I have been looking for such a device for some time.
Ideally something I could set a current in that would never be exceeded by either PWM on the input or direction to a dump load. Wouldn't worry me but would be very useful.
I was looking last night and found an ACS 759? sensor that could be coupled to an arduino to perform such a task.They do 50 or 100A so well in current spec and I surmise from what I have read they will do suitable voltage but couldn't find the specs on that anywhere.
The programing would be a bit involved I think and I'd much prefer to just buy something commercially made.
I would like something to do mains AC where as what you need is DC and in my limited knowledge, that seems a lot harder to do in high voltage DC.
Quote from: glort on February 06, 2019, 04:42:32 AM
I would like something to do mains AC where as what you need is DC and in my limited knowledge, that seems a lot harder to do in high voltage DC.
In my experience, DC is much easier to control that AC because of the AC zero crossing timing. I can control the current after the rectifier on the DC side or before on the AC side, so I have a choice.
In DC, you just change the duration of the pulse. I too was hoping there was a device already available but it does not look hopeful. The Arduino will have to control the PWM current control at the same time as the throttle of the engine. It will take some playing to coordinate the two and I don't have a handle on the mechanics of the throttle control servo mechanism. So, another aspect of the project to research ...
Would sure be simpler if the SMA Sonnyboy MPPT could be changed to an RPM associated table curve instead.
Does anyone have experience playing with (setting up) the Sonnyboy MPPT?
Darn. My spare is hidden under the work bench just in case my Sunny Boy goes South. The plan would be to swap them out and then use the yellow Sunny Boy cover to hide my deed. How about a search on eBay as I have for the Sunny Island device.
Quote from: LowGear on February 07, 2019, 11:52:43 AM
How about a search on eBay
Yeh, been there done that ... There is only one that shows up and it is too small. I need at least a 5000 - 6000 watt one. I have phoned a bunch of dealers, repairers, and installers, to no avail.
The three products that would work and are grid-tie certified here are:
- SMA Windyboy, - ABB Power-One, - Ginlong Solis, in the 5-7 kW range with single phase output.
I have asked a couple of installers if a Sonnyboy can be converted to a Windyboy and the answer is always - NO. Different beasts. The MPPT is not changeable.
What model of the power one's?
I have several, 2 kw and 3.6 Kw units and have used them in this setup. Can be seen in my Vids. They definately Hunt searching for peak power.
Quote from: glort on February 08, 2019, 08:44:12 PM
What model of the power one's?
I have several, 2 kw and 3.6 Kw units and have used them in this setup. Can be seen in my Vids. They definately Hunt searching for peak power.
are they solar models or wind models?
The ABB PVI-5000/6000-TL-OUTD (North America) is one ...
Remind me again of the benefit of that inverter to your purposes?
If it is the idea they don't ramp up and down looking for the sweet spot of the input, I would be extremely surprised if that is not exactly what they do.
I know the ones I do certainly are like that and I see nothing different in these other than being higher capacity than the ones I have.
Are you intending to modify them or is there something I have missed ( which wouldn't be hard!)
I'm confused. There are many Sunny Boy inverters on the US eBay site. These are one program intervention away from being Windy Boys. That's a free download or was a few years ago. I'm thinking the cable is about $25. And they're no longer the >$1500 that I paid for my first Sunny Boy. That's why I couldn't say "No" to the Windy Boy when it flashed up on the screen at something less than $1000.
I Just bought another aurora 3.6 with 4kw of 260W panels this weekend. $400 all up.
I'll keep the panels and start replacing some of the smaller ones I have with the 260's. I'll be able to sell the smaller ones for more than I paid for the 260's. The inverter is a good score. panels are easy to get and last a long time. Used inverters coming onto the market are earlier generations and there isn't so many of them as they last no nearly as long as panels.
I have 5 Kw Sunny boy that has a fault but isn't that old. Tossing up wether to have it repaired. There is a guy not too far away that quotes $150 for all repairs. Might be worth while as I'll need a 5 Kw soon for the north roof of the house. Then again if it can be programed to a wind configuration and I can get the program.... Might be better for other things.
Just got a 12 KW motor to set up as an IMAG so the sunnyboy would be ideal for that but then agaqin, can always hook it direct to the power supply as I am not concerned about meeting any stipulations for getting payment or credit.
Quote from: LowGear on February 16, 2019, 09:48:34 AM
These are one program intervention away from being Windy Boys. That's a free download or was a few years ago.
Everyone I talked to said that a Sonny Boy could not be changed to a Windy Boy. Please tell me more about this! Where did you get your information?
Quote from: glort on February 11, 2019, 04:47:34 AM
If it is the idea they don't ramp up and down looking for the sweet spot of the input
Are you intending to modify them or is there something I have missed ( which wouldn't be hard!)
The difference between a Sonny Boy and a Windy Boy is the MPPT method. The Windy Boy does NOT ramp up and down looking for the sweet spot. It has an RPM input and compares the generator RPM to the table curve to determine the current draw. No hunting. If the generator is turning this fast, draw that amount of current.
LowGear has posted that the Sonny Boy MPPT can be converted to a Windy Boy type of MPPT algorithm. If this is the case, I will be a happy man!
Any info I can get on this procedure is greatly appreciated!
So the windy would need to be programed to each individual alternator so it knew what it was going to be doing at a certain output.
How would that be achieved? You would need to connect the alternator to a motor of some sort and run it from zero to max RPM to build the reference table would you not or have one from the manufacturer of the alt with a certain specfic blade in this case.
I just need to work out the best way to mount my 180Kg Motor and 70Kg engine now.
Thinking to mount them both solid and use a belt tension instead of having them on rails to adjust the tension.
Quote from: glort on February 18, 2019, 01:06:50 AM
So the windy would need to be programed to each individual alternator so it knew what it was going to be doing at a certain output.
You would need to connect the alternator to a motor of some sort and run it from zero to max RPM to build the reference table would you not or have one from the manufacturer of the alt with a certain specfic blade in this case.
It is my understanding that they came with a default table and then you manually "tuned" the points in the table (around 10) for your specific generator. The MPPT algorithm then used these points to create a power curve for RPM to Current Draw calculation.
SMA programming. Sorry, I've been on a visit to the mainland. Phone technical support at SMA USA for clear reliable advice. My SunnyBoy was just adjusted to Line voltage parameters. When I inquired, many years ago, I was lead to believe the WindyBoy was the same device with modified software algorithms.
If I'm wrong I must just have WindyBoy 7000 for sale but shipping from Hawaii would not be cheap. They weigh about 150 pounds. We might look for a trade as well.
Thanks LowGear. I have talked to SMA before, but I just tried again, and they do not like the idea that I am doing something other that solar. They were NOT helpful at all. I did manage to get him to admit that the parameters can be changed. I asked for some documentation on the parameters but all he would tell me is: read the installation manual. I downloaded it and all it contains is paragraph on how to access the parameter menu in the unit. It does not mention any particular parameter or what they do.
I have also sent a query to ABB. We will see what they say ...
Definitely let me know if that windy boy doesn't work out for you, I am interested ....
I think I can see why this is allowed in Canada where it would not be in so many other places.
The Canadians have worked out how damn difficult and costly this can be and realised 99 out of 100 people are probably going to give up before they get started.
SMA have a reputation here for being unhelpful, especially when it comes to warranty claims. They used to be one of the Pet/ darling brands but their recommendation has slipped substantially due to their less than outstanding customer service and their products not living up to the reputation they once had.
I don't think I'd confuse SMA with details. They were slow to tell me that they didn't want me inside the cover because of safety concerns rather than damaging the equipment. Finally they admitted they were concerned about user safety. Doing something not in the pamphlet might require medical attention. The software used to be available on their website.
Quote from: LowGear on February 20, 2019, 10:18:06 AM
The software used to be available on their website.
i had a pretty thorough look through the web site and all I found was two firmware updates with no info on what they were about.
So here is where I am at ... I have figured out how to deal with the MPPT/governor conflict. A diesel generator governor is designed to maintain the set RPM when the load changes. Other diesel engine uses (automotive) do not have that type of governor. For example an automotive engine governor is designed to protect against under-speed and over-speed, it doesn't care if the RPM changes with load.
My plan now is to couple a VW engine with a 3 phase IMAG, rectify the unregulated wild AC and feed a Certified grid-tie solar string inverter. So, in effect, it will be like running the IMAG as a standalone generator.
What I am not sure about at this point is:
will the IMAG maintain its "flash" at varying RPMs, particularly lower RPMs? How low?
what load will the IMAG handle before loosing its "flash"? 50% of name plate?
I am sure some of you guys know this stuff or could point me in the right direction.
Should I cross post this to the " Induction generator" category?
What is IMAG ?
A regular alternator looses it's flash magnetism if it spins down with a load connected. Always make sure you have fuel, and cut breakers off and let genset run a few minutes to cool down before shutting down.
IMAG = Induction Motor As Generator
Quote from: bryanb on March 26, 2019, 11:09:45 AM
What I am not sure about at this point is:
will the IMAG maintain its "flash" at varying RPMs, particularly lower RPMs? How low?
what load will the IMAG handle before loosing its "flash"? 50% of name plate?
I am sure some of you guys know this stuff or could point me in the right direction.
Where the IMAG will stay energized depends on how much capacitance you are running.
There is a fair amount of " Tuning" you can do with this. If you up the Capacitance you will get more stability and the power will come in early but tends in my experience to be very peaky. Small changes is RPM make big Changes in Voltage but if you are running fixed throttle and relatively fixed load, shouldn't be all that big a deal as you can wind the throttle to give what you want.
I'd be aiming at around 300V at the RPM you want to run on the AC side which will give 430? or so DC. That will will be in the range of the GTI which are all 600V now. This will give you plenty of head room and a margin below.
Far as I am aware the imag will loose generation at below nameplate RPM But I have gone below this using a lot of capacitance for the size motor I'm running. Slower running leads to less stability and easier to crash the field in the winding's.
I have run high and low capacitance over recommended and it all works, just has different effects. Low tends to need higher speeds to kick in which gives higher frequency ( not something you will have to worry about rectifying) and lower give more power at lower speeds and Higher voltage which is easy to exceed the caps rating so be careful. Use the highest voltage caps you can find and not below 500V.
Don't forget with RPM you can always gear up the driving engine providing it has the grunt and run it a lot slower than the motor. I am ( still) Building my setup with the 12 KW motor and a 12 Hp Diesel. I'm going to run the diesel at about 50% RPM. I can't pump any more than about 5kw direct down the line in the setup I'm going to use it for so the engine will have excess power I'm going to utilise in torque and lower running speed. I have been running it a bit for testing and it is a noisy bastard. Really need a water cooled like a little Kubota or yanmar.
AS for not running a governor, I think this will help but I'm far from sure it will fix the hunting problem.
The trackers in the inverter will be still trying to vary the load and the engine will feel that and I believe the same see sawing effect will happen. To what extent remains to be seen.
What I would suggest is add as much flywheel weight as you can so you have more reactive power. I picked up a couple of old truck flywheels the other day which must weigh 25Kg each.
I'm thinking to put them on a shaft and belt drive them to the load or the engine, won't matter, to help smooth things out. It may help in this case too, bit hard to say but I think it will reduce the effect if it does not fix it.
Another thing that may help is put some caps in the DC line to the inverter. Might help smooth things that way too.
I will need to run this thing from idle to full throttle for variable heat outputs so it sounds like an Induction Motor As Generator is not going to work. The other options I can think of are:
1) Permanent magnet 3 phase generator (or motor). I have a 23 hp low RPM (100 rpm) which is difficult to drive that slow.
2) DC generator (or motor). Large permanent magnet motors are not common (expensive), I may be able to get a 15 - 20 hp DC motor with controllable field.
3) Standard 3 phase generator using the wild AC with the voltage regulator disabled. Is this possible? Do I just power the field full voltage all the time and the engine rpm determines the output?
I would like to stay as close to reproducible as possible so others can do this too, so my preference is to use a standard AC generator head (choice # 3). Does anyone know how I would determine what the excitation voltage is for a typical generator head?
Quote from: bryanb on April 04, 2019, 12:18:21 PM
3) Standard 3 phase generator using the wild AC with the voltage regulator disabled. Is this possible? Do I just power the field full voltage all the time and the engine rpm determines the output?.
Engine RPM will affect the voltage output, and at some low RPM (generator going below 40Hz) the generator will poop out.
You should look at some of the Axial Flux alternator designs, that are used on DIY wind turbines
http://www.windsine.org/2017/02/07/listeroid-backup-generator/
Quote from: mike90045 on April 04, 2019, 10:46:30 PM
and at some low RPM (generator going below 40Hz) the generator will poop out.
Why does it "poop out"? Can I increase the excitation voltage at lower RPMs to maintain output? What about a permanent magnet generator?