PWM control of GTI from a distance

[noneyabussiness]

Hey all, been testing this for a bit now, and I'm confident it is achievable with a arduino and a nrf24l01 module,  I have a wotking prototype... I was thinking of a issue Clockman had, trying to regulate his GTI's from a significant distance and I've also come accross this need.. so Ill put up code for the arduinos and If anyone has comments or suggestions please let me know..

Ive added comments and left the original pinout description in the transmit INO.. personally tested these modules ( with booster and antenna)  to 700 meters open field / line of sight.. as this is a " bang bang " type pwm for my setup, it can also be easily modified for progressive pwm..

hope this helps someone .

[noneyabussiness]

OK, so found a minor fault, would after a undetermined amount of time, lock up and send full stops, so moved the watchdog reset flag into the" send " loop... so if it doesn't receive anything for 8 secs the WDT will reset chip... no more lock ups ...

[clockmanFRA]

Nice one 'noneyabussiness'.

Yea, getting a quality tx and rx, and good code set up, that actually works and lasts is excellent.

Moderators please, feel free to make the below more grammatically correct and better English.

Those of you who are not sure whats going on here, its all about AC coupling used/old GTI's, (Grid tied Inverters).

Normally ordinary GTI's are designed to be Grid Tied into your utilities supply, and push the voltage up a few volts and back feed to your utilities at a local level,  and your meter goes  backwards, (it may not, but you get the drift).

When you have an offgrid system, normally its PV etc, to DC charge controllers that then charge batteries and the batteries run your Power Inverter , ie 24vdc or 48vdc to 120vac or 230vac.

A bigger system that has over 800ah of batteries can now work with GTI's AC coupling if your Power Inverter is a H Bridge design. Ac coupling simplifies the system.

So your GTI is now connected to your 120vac or 230vac, that your Power Inverter is creating. The GTI needs to see a good stable HZ and stable AC voltage.

Once your GTI is gone through its start up procedure and is happy, it then feeds into your Power Inverter created Mini Grid, and  the power can be used.  However, power not being used by the Mini Grid is then pushed back through your Power Inverter and charges your battery bank.

There are some rules/criteria that must be followed with this type of AC Coupling arrangement.

Most old/used GTI's are MPPT and are fairly robust, well mine are, and its a cheap way of getting extra power from a RE source like PV etc.

What 'noneyabuissness' has done is devised a system that controls the GTI and shuts it down if the battery bank is fully charged and no power on the Mini Grid is being used.

I use Voltage comparators that watch the battery voltage at each GTI to shut them down, or i manipulate the GTI's internall settings, so instead of the GTI going to say the normal 256vac push back into your Mini Grid, i can set the GTI to shut down at 247vac.

There are other ways of managing the GTI's,  but a wireless dependable system where the GTI could be on another building 700 feet away and does not need a data cable, that is along side the 120vac or 230vac power cable from the main battery bank and Power Inverter, is good.   

'Noneyabussiness', I look forward to looking to your photos and write up.  Thanks.

[SparWeb]

As moderator: I see nothing needing fixing in your explanation, Clockman!

As user: I'm looking at my options to configure this myself these days, so thanks for posting noneyabusiness!
I'll add my own note that when GTI has excess to "sell" to the mini-grid, but the off-grid inverter has a full battery bank, I'm considering keeping my diversion load controller on the system to just dump off heat when the batteries are full.  I can come up with more nuanced ways to use the extra energy productively - after I get the two inverters talking nicely to each other, first.

[noneyabussiness]

hey Clockman,  so Ive attached some pics of my setup, and it is working well, made a few more modifications to the code for more redundancy, slowed the Mosfet update down as again more suitable for my setup... but all configurable...

the big one is a RGB led ive set up as a heartbeat,  so as long as each second the nrf24l01 receives a signal, it pulses ...

[noneyabussiness]

tried putting pics up... too big, so I'll compress them and post em up...

or look here...

http://www.thebackshed.com/forum/ViewTopic_mobile.php?FID=4&TID=15345&PID=194402&LastEntry=#194402

[mab]

As user: I'm looking at my options to configure this myself these days, so thanks for posting noneyabusiness!
I'll add my own note that when GTI has excess to "sell" to the mini-grid, but the off-grid inverter has a full battery bank, I'm considering keeping my diversion load controller on the system to just dump off heat when the batteries are full.  I can come up with more nuanced ways to use the extra energy productively - after I get the two inverters talking nicely to each other, first.

I've followed you're philosophy on my system Spar' - i don't curtail the gti's,  i have dump loads to use the power.

I currently have 4.5kw of solar ac coupled via 3 gti's to my '8kw' (2kva worth of transformer) powerjack inverter, and about 1000w solar and hydro d.c. coupled.

I have about 3kw of d.c. dump loads:
Immersion heater
Big resistor in the shed (this one shouldn't normally come on - it's the final safety net in case one of the other dump loads fails),

and 3.5kw of a.c. coupled dumploads:
1.5kw storage heater
2.2kw storage heater
The idea being that the powerjack never has to handle more than 2kw cont throughput, and if the powerjack were to go offline there's still enough dc diversion to cover the dc inputs.

It is a potentially useful resource to have noneya's and CM's curtailment methods to use in the summer though, as i don't really need to store heat when it's hot - the plan is to have a heat pump installed before next summer though, and that can be run in reverse to provide cooling instead.