design techniques for turn-off when grid goes down

[MPaulHolmes]

I hope this area is acceptable for a technical discussion on safely shutting down an inverter when the grid goes down. I heard one interesting thing in a different forum on here about injecting distortion to see if it's absorbed by the low impedance grid. Are there other techniques? As a side note, if it's not OK to talk about this here, is there a solar energy technology website that someone could refer me to that doesn't mind technical questions about making your own grid tie inverter? Just because I'm making my own doesn't mean I'm going to break any laws.

[russ]

I hope this area is acceptable for a technical discussion on safely shutting down an inverter when the grid goes down. I heard one interesting thing in a different forum on here about injecting distortion to see if it's absorbed by the low impedance grid. Are there other techniques? As a side note, if it's not OK to talk about this here, is there a solar energy technology website that someone could refer me to that doesn't mind technical questions about making your own grid tie inverter? Just because I'm making my own doesn't mean I'm going to break any laws.

Only when you use it will you be breaking the law. Don't try to feed anyone the blather you will get it approved by UL or whoever.

I suggest you drop the subject here and look elsewhere - otherwise I will close it again.

[MPaulHolmes]

Only when you use it will you be breaking the law. Don't try to feed anyone the blather you will get it approved by UL or whoever.

I suggest you drop the subject here and look elsewhere - otherwise I will close it again.

Okay, could someone point me in the right direction where technical discussion is allowed pertaining to grid tie inverters? Is there a list of forums that someone could post?

[Mike90250]

Because this forum is hosted in the USA, and some of the moderators and posters are responsible, licensed electrical contractors, discussing illegal installs/grid connections, is a non-starter for any forum/board at solarpaneltalk.com We just are not going to go there, except to tell you NO.

[MPaulHolmes]

Because this forum is hosted in the USA, and some of the moderators and posters are responsible, licensed electrical contractors, discussing illegal installs/grid connections, is a non-starter for any forum/board at solarpaneltalk.com We just are not going to go there, except to tell you NO.

Is there an equivalent of a solarpaneltalk that is a little more engineering focused? Like a solar tech forum? At this point I'm just asking for links.

[inetdog]

Is there an equivalent of a solarpaneltalk that is a little more engineering focused? Like a solar tech forum? At this point I'm just asking for links.

Don't know about discussions in particular, but simple Google searches will find lots of publications about testing of Anti-islanding, and overall A-I strategies, just no really good implementation details since those are proprietary designs.
'Nuff said....

[MPaulHolmes]

Don't know about discussions in particular, but simple Google searches will find lots of publications about testing of Anti-islanding, and overall A-I strategies, just no really good implementation details since those are proprietary designs.
'Nuff said....

A few years ago, I found the EV Tech list, which is a technical discussion relating to electric vehicles. I had started an open source motor controller project so people could assemble their own controller for about 1/4 or 1/3 the price of a comparable motor controller. Now there are hundreds of DIY EVs on the road, many of which wouldn't be otherwise. The EV Tech list was invaluable for offering suggestions and help along the way. I could have just read snippits about proprietary methods of motor control from google searches, but the human back and forth was so much more helpful. It sounds like an open source grid tie inverter would be useful if it's all just proprietary at this point. In spite of russ's objections, there's no reason why it couldn't be tested and certified as well. It seems like a solar forum would be a good place for such a back and forth. I guess I'll look elsewhere.

[Sunking]

I guess I'll look elsewhere.

You are going to have to. FWIW I am one of those EV guys you talk about on the DIY EV FORUM. However Auto EV manufactures do not use PWM controllers on EV's, they use proprietary VFD and AC motors

Here on this forum you are not going to find equipment engineers. No equipment engineer is going to tell you how they do what they do. It is proprietary and we do not give our work away. You have to pay for it just like we did with education, years of experience, and tons of investment money. Why on earth would we give it away? Are you going to pay my rent?

[MPaulHolmes]

Also, I'm just finishing a 3 phase FOC AC controller that's around 150kw, and the code is open. Turnakado devel also is doing AC FOC open source. I don't think there's any area of renewable energy that is a sacred cow that shouldn't be layed bare for the world to see.

[SunEagle]

A few years ago, I found the EV Tech list, which is a technical discussion relating to electric vehicles. I had started an open source motor controller project so people could assemble their own controller for about 1/4 or 1/3 the price of a comparable motor controller. Now there are hundreds of DIY EVs on the road, many of which wouldn't be otherwise. The EV Tech list was invaluable for offering suggestions and help along the way. I could have just read snippits about proprietary methods of motor control from google searches, but the human back and forth was so much more helpful. It sounds like an open source grid tie inverter would be useful if it's all just proprietary at this point. In spite of russ's objections, there's no reason why it couldn't be tested and certified as well. It seems like a solar forum would be a good place for such a back and forth. I guess I'll look elsewhere.

You really can't compare a group of people designing an EV to a DIY grid tie solar system. As long as the EV meets all DMV rules (lights, safety gear, fenders, etc) how it is propelled is a mute point (except maybe via thermo-nuclear).

With a grid tie system you are now crossing over into the Utility's area and they have much more stringent safety rules. Since any DIY anti-island sensing system can fail due to poor design or bad installation a forum like this can't share ideas that may result in someone getting hurt.

I wish you luck in your search for a real techy DIY forum.

[green]

Why try to reinvent the wheel anyways. There are anti-islanding inverters that are UL listed and approved for installation through proper permitting. Why try to make one yourself? I'm a DIYer that loves to build and create and I wouldn't touch anything like that.

[Mike90250]

... In spite of russ's objections, there's no reason why it couldn't be tested and certified as well. It seems like a solar forum would be a good place for such a back and forth. I guess I'll look elsewhere.

There is about $100,000 or more, reasons why it's unlikely to be certified. UL approval testing is prohibitively expensive. You have to supply several devices from the production line (not engineering prototypes) and several get tested to the point of flames. They burn them up. On purpose. At 2x rated system voltage. They study the smoke and fumes for toxic gases. They look for things inside that explode. And then they bill you for it. And they decide after the test, what they will charge. And you pay. Then you find out if it passes or fails. And I don't think they tell you WHY something fails, other than the name of the failing test. Retests cost the same, no discount. And the UL cert makes the insurance company happy. You don't get far without the cert.

[Sunking]

Also, I'm just finishing a 3 phase FOC AC controller that's around 150kw, and the code is open. Turnakado devel also is doing AC FOC open source. I don't think there's any area of renewable energy that is a sacred cow that shouldn't be layed bare for the world to see.

The sacred cow as you call it is real simple. People like me do not invest 6 years of college, millions in prototype design, trial and error, and years of development to just give it away. That is not how the world works.

You can get the basic design schematics from the IC makers.

[russ]

[QUOTE=MPaulHolmes;74759 It sounds like an open source grid tie inverter would be useful if it's all just proprietary at this point. In spite of russ's objections, there's no reason why it couldn't be tested and certified as well. It seems like a solar forum would be a good place for such a back and forth. I guess I'll look elsewhere.[/QUOTE]

Come on! An open source inverter - that every individual must have UL listed at great cost? You are a hard headed student or just smoking something?

Not my objections - code objections.

[Sunny Solar]

Certification is always the biggest and most expensive part of anything to use on the grid. Its part of my job to test and evaluate manufacturers products.Its very time consuming and requires a lot of expensive test equipment.
Its not that difficult to get a battery inverter to sync with a GT inverter .I managed it with only destroying 3 x1000w battery inverters and 3x 1k5 GT inverters. But really thats hardly a bargain for a DYI person.. If I had to pay for those items of course I would not have done it. Far far cheaper to buy one designed to do exactly that.
BUT there is always a but. Would it pass anyones certification my modified items??? NO NOT ANYWHERE ON THIS PLANET.
They would be regarded as illegal anywhere there are rules governing such things. And for this reason dont wait for me to tell you how it can be done. I dont help people do illegal builds or mods. I did mine at work under controlled conditions. then after testing were tagged as not to be used outside the test area. .