Author Topic: OzInverter Mini Grid, AC Coupling GTI’s Control.  (Read 5751 times)

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Offline ClockmanFrance

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OzInverter Mini Grid, AC Coupling GTI’s Control.
« on: June 02, 2017, 01:52:40 pm »
Here we are Fionn, away from Oztules topic.

OzInverter Mini Grid, AC Coupling GTI’s Control.

Its summer here and I am trying to be a little more gentle with my batteries.  !

We are using the 230vac Voltage increase to shut down the GTI’s,  (Grid Tied Inverter) when  backfeeding through the OzInverter to charge the batteries and the batteries are full.

Ie. The batteries full, we switch off the GTI when the AC voltage rises due to push back from the batteries.
However, with AC and DC renewable energy power creation system the DC Wind turbine dump loads have a habit of trying to dump excess created solar when the batteries are full and DC charging has shifted to float.  Yes I can load shed, make Megas that recognise float and send signals to the GTI’s, or using Aux contacts on my DC charge controllers etc.
 
All the GTI’s that I have here seems to have different shut down voltages. I can gain access internally; I have access codes, to alter the AC shut down voltages. Great for me, but not easy for other folk around the World, and the different manufacturers and models of GTI’s out there.

I have observed with my OzInverter that the AC Mini Grid Voltage still rises when the batteries are full and the DC Dump loads are operating, so the full batteries are still giving sufficient back push to rise the AC but not fully. But as I have found out not all the GTI’s shut down as they should.


The required circuit......

So this fool reckons that to keep things simple……. Why not a simple circuit that  is actually at each GTI installation, mine are up to 500 meters apart, that looks at the local AC Mini Grid AC voltage rise and operates a relay on the AC output of the GTI.
The Circuit will need to be sensitive to the AC voltage increase, and be settable at the actual GTI installation. Obviously there is AC power, and  no need for hideous lengths of data cables.


230vac Range… ..............
Under load the OzInverter goes down to 227vac, …….. batteries full and pushing back and operating the DC dump loads ….. 242vac. No DC dumploads……. 258vac


Example………..
Mrs Noggins, staying in our Gite’s, (holiday accommodation) and its summer, uses  her 2kW hair dryer, the AC voltage drops, the OzInverter and its batteries take the load for a few minutes while the local PV GTI starts itself up again, then copes with the 2kW and then backfeeds into the batteries for a short while until they push back, AC voltage rises again GTI shuts down.
 
Okay bright sparks, anyone know of an existing simple sensitive circuit I can rearrange for my purpose. Or is it the design board?

Thanks.

Pic ..... The latest 5kW PV installation running on the OzInverter Mini Grid, 500 meters away from the OzInverter and its batteries.

Offline oztules

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Re: OzInverter Mini Grid, AC Coupling GTI’s Control.
« Reply #1 on: June 02, 2017, 03:31:43 pm »
It is very simple to do.

As you now have arduino available, you can use that for a window comparator.

Simply get a 12v transformer ( like on the control board ), use that to both drive the arduino, and use it as a voltage source for your comparison... write simple program to sense the voltage, and make a decision..... barely any parts, and fully programmable.. ( the nano will take any voltage up to about 20v and convert it to it's required voltage.. so it does not matter that the transformer output changes for it's run voltage, it has it's own regulator

But the transformer will be able to tell the nano whats going on outside, via the changing secondary voltages.

Perhaps use  a triac to connect the GTI.... triac and triac opto driver should not load up the little nano circuit.

The other way is to use just a comparator, but you can't make informed decisions as you can with the nano... ie once awakened, run for 5 mins more etc. The nano will give you full control of the environment the GTI runs in.

.........oztules
Flinders Island...... Australia

Offline ClockmanFrance

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Re: OzInverter Mini Grid, AC Coupling GTI’s Control.
« Reply #2 on: June 03, 2017, 03:15:59 pm »
Thanks Oztules.

I will bread board and see how things go.

Offline solarnewbee

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Re: OzInverter Mini Grid, AC Coupling GTI’s Control.
« Reply #3 on: July 03, 2017, 08:44:11 pm »
check out cayenne.mydevices.com

you can connect to their cloud server and build a dashboard with very little code, using a esp12e or a ethernet shield or esp8266(includes wifi)  as your arduino instead.
set triggers (if voltage 1 is above or below then do this action and it can also notify you by text and email of any event you want to monitor.
dashboards can be monitored on iOS, Android and most web browsers. there is scheduling to set times and dates for actions you want to commence.
they have a community for assisting first time users of their site and many topics to search to solve issues on your own.

check out my dashboard  https://cayenne.mydevices.com/shared/59598d2add9f5e4dd3b960de

SN
SN

Any day above ground is a day for potential mishaps