GridTie Synchronous Generation Project Using Carbon Neutral Flare Gas

[looking]

TL;DR Summary

Project has advanced from a professionally drawn one line diagram accepted by electrical utility; CSA approval of entire generation/rectifier/wind inverter apparatus; electrician wired install and "short experimental test". EVERYTHING worked to complete satisfaction. Inspectors being scheduled .
I invite suggestions on converting the constant voltage generation source power to a constant current source so more readily available solar grid tie inverters may be used.

Details to follow if there is interest.

 

[anorlunda]

Details to follow if there is interest.

Don't be shy. Go ahead and ask your question.

 

[looking]

OK...So after much effort and red tape it is all but proven that worth less than nothing good quality flare gas (casing gas) can produce tens of kilowats of grid tied synchronous (gen set driven by said energy source) with CSA approved wind grid tied inverters. And through such a simple, safe and now approved electrical apparatus has been fully certified One wonders how someone else in the world hasn't done this some decades ago. Further proof of my above analysis is that only when the electrical inspector soon checks the electrician's work; has the utility electrical engineer asked to simultaneously witness the commissioning. And it is also heartening to note positive comments from industry, and even environmentalists and the Ministry of Economy (Energy and Mines) etc.etc .But...One major problem for scaling and repeating this demonstration project is that no North American certified smaller scale wind inverters are available as of about 5 years ago. Thats a story in itself but boils down to manufacturers deciding if you want renewable resource energy; then spend your money on solar instead of thinking about problematic controlling wind turbine blades that in first high wind may cause inverter magic smoke. So to stop warranty returns everyone is advised to forget small scale wind. Basically end of story as of 5 years ago..
So as I said in the summary I invite suggestions on converting the constant voltage generation source power to a constant current source so more readily available solar grid tie inverters may be used.

If only there were a simple way to change the natural gas driven gen sets output from its "constant voltage source" characteristic that wind inverters work with like a charm (as in they will probably never ever be problematic)
TO A "CONSTANT CURRENT SOURCE which more widely avaiable "Grid Tie CSA Solar Inverters" are made to use.

Please suggest the simplest and cheapest way to convert the rectified output of a synchronous AC generator from a voltage source to a current source that solar inverter can utilize.

Now putting enough energy behind a pig and you can make it fly. But I'd like to accomplish the same thing by maybe feeding a VFD (Variable Frequency Drive) with the AC power and hopefullyin something like the "Constant Torque" mode (Volts/Hertz mode) create a fixed output related to constant current which would be in acceptable range of overdriving a solar inverter with a pretty constant rectifiedDC Current...ior your other more workable and suitable solution. Thanks for comments and suggestions

g

 

[anorlunda]

OK, this sounds like a continuation of your earlier thread.
https://www.physicsforums.com/threads/connect-grid-tied-solar-inverter-to-dc-bus-of-vfd.965781

Your questions are confusing, but here is my interpretation. CSA is your local power company. CSA will not allow you to connect to the grid except through an approved grid tie inverter. At your scale, the approved grid tie inverters are designed for solar DC, but you want to use it with a gas powered genset with an AC synchronous generator. Is that a correct summary?

Your problem is 10% engineering, 50% rules and regulations, and 40% markets. I say markets because your needs are unusual whereas the markets offer products for the more typical cases that have more customers.

Let's start with the basics. What is the maximum power you can make? Please give links to the grid-tie inverters that are approved by CSA? We'll try to see if you can match them.

 

[looking]

If I may; its 90% red tape and regulation; where near electrical monopolies didn't allow new entrants till last few years where homeowners were allowed some limited entry. But that can be handled with perservance and living within the standards. Marketing is for the future and will be someone elses opportunity (in this case)

Ok I should have defined what CSA means. Canadian Standards Association; and is the Canadian version of UL in the USA. You just got to have the CSA sticker on every genset and every grid tied inverter and every component like the 3 phase rectifier has to be approved by some international standard and it appropriate marking or stamp attached. And then that's only the beginning of the necessary approval. You go to an independent approval agency that field approves your entire apparatus (genset, DC rectifier, setup and grid tie inverter).

Been there done that and surprisingly it can be a very pleasant experience and only costs about $560.00 if you've got your design in order.

Now for your questions. For the next prototype I want to feed a 28KW 3 ph 480V Yaskawa solar inverter. Need some "constant current source power" . to feed the proposed solar inverter. Yaskawa solar inverter is rated up to 1000VDC but anything over 300VDC would be appropriate.
Sorry about past post. Cell phones tend to send messages and lose longer s without warning

 

[anorlunda]

OK, now you're getting closer.

See the attached curve. A solar panel is both constant voltage (nearly vertical on the curve) and constant current (nearly horizontal on the curve). The MPPT (maximum power point transfer) is right at the knee, halfway between constant voltage and constant power.

A synchronous generator has a closed loop feedback loop that controls terminal voltage by adjustments in field voltage. Someone skilled in feedback control system design, could alter that loop to achieve goals other than constant voltage.

But I think the real issue is not that the inverter requires constant current, but that the inverter includes its own MPPT feedback loop expecting to control a solar panel. By far the simplest and cheapest thing you could do would be to turn off the MPPT feature of the inverter. Study of the owner's manual may reveal how to do it. If not, then I would call Yaskawa and ask to speak to an engineer and ask him how to make it work with the rectified output of a synchronous generator. On second thought, I would consult with the Yaskawa engineer in any case. He might be aware of opportunities and pitfalls that you need to know about.

My guess is that working with the inverter is far easier then redesigning the generator's voltage control.

By the way, do you have a CSA approved full wave 3 phase rectifier?

 

[Dullard]

There are switching power supplies which will do what you want: convert your generator output to a regulated DC current. I assume that most solar inverters are designed to find the maximum power point for a (presumed) PV panel I-V curve - I'm not sure exactly how they do that (these days) - that will probably have to be disabled.

I've been on drilling sites in Texas, Arkansas, Pennsylvania... The reason that 'someone else' hasn't done this is fairly obvious:

Most drill sites don't have street addresses or grid service. How much money are you willing to spend on transmission lines to add 10 KW to the grid? I have seen flare gas used for on-site power, and I'm sure that there are situations where the economics could work - I've never seen one of those situations.

 

[looking]

Multiple excellent thoughts and leads anorunda and dullard. Thankyou and I will certainly follow up several of them.

And yes the 6 pulse 3 phase rectifier did pass the Intertek certification for Canadian for CSA equivalency. It is considered a "component" piece and has a European mark ( CE comes to mind) and there wasn't any problem after (as I remember it) I provided the manufacturers spec sheet. I could get the brand if anyone wishes.

I have concluded that in addition to drill sites often being in remote area; those same sites may require 3 phase infrastructure to enable pumping, compressing injecting salt water etc etc. And utilities particularly in the past 6 months are keen to at least entertain small power producers and net metering etc. In addition; paying Canadian carbon taxes (25% to 40% of electrical and natural gas usage adds up and along with demand charges is a significant cost to the oil industry.

And finally there are two points that most would miss until they have gained the same experience I have paid for in many ways. Utilities want a lot more than Kilowatts. They want an ideal power factor and they want it "clean" of harmonics and absolutely safe from any impact on their grid or work persons. And that's why solar and wind inverters appeal to utilities engineers. And boy does it make things possible that wouldn't even have been tried as recently as 6 months ago . Then the final kicker that in Saskatchewan; we can even label flare gas generation as "Carbon neutral" generation. Its even in the same category as low impact hydo generation, solar, and geothermal. And that same mandate now permeates our Crown utilities and Provincial Ministries and regulatory bodies which for resource and mineral production is under provincial control. When it gets to automotive and manufactured fossil fuel products then The Feds grab their share and maintain control.
Please keep thsose new thoughs flowing and I'll keep in touch too.

Lots of interesting things to learn; but you work with what you're given as parameters.

Any further or extra thoughts and ideas are gratefully accepted. I've also always been willing to share what I have found to be true.

 

[Dullard]

Sounds as if you might have found a regulatory 'sweet spot.'

 

[Baluncore]

You might consider using the energy to charge electric vehicles directly without connection to the grid. The capacity of EVs to store and use the energy is limited only by the number of EVs available locally.