Advice – Anti Islanding Protection GTI

[007 RED]

My very basic understanding of anti islanding protection is that in the event that the grid power supply is interrupted, the GTI should almost instantaneously detect the grid ‘drop out’ and stop producing power.  This being a safety feature to prevent someone working on the grid getting a shock and also to stop the inverter from ‘running away’ and burning itself out.

 

We are fairly lucky that we don’t get many power interruption, but this morning at about 09:30 the power went off – no water pump; fan; TV etc.  This being the first time this has happened since I installed my small scale GTI system some 5 months ago.

 

After about 5 minutes or so I decided to pop outside to have a look at the meter to check that the anti islanding protection had kicked in.  Low and behold the disc was spinning backwards at a fair rate of knots (good sunshine this morning).  I went to the car port and turned on the light switch (LEDs) and they came on.  I noted that the indicator light on the GTI was on (green) but I could not see the LED display message because the GTI is mounted high up.

 

As I returned to the house it was evident that the power had come back on.  I later got the ladder out and checked the LED display which read ‘Normal’ plus the power output reading (kW) at the time.  There were on error messages displayed.

 

From the GTI's installation manual, I understand that on power up the GTI automatically does a series of safety checks and if the any of the internal protection devices (including the anti islanding feature) are not functioning it would go into a ‘Fault’ state and show the respective error code in the LED display.

 

Obviously I’m concerned by seeing the meter disc spinning backwards.  What I don’t know is at the time I went to the meter was the grid power back on or was the grid power still off and the GTI feeding power back into the grid.

 

My question being, is there any simple way to test the anti islanding protection is functioning correctly?

 

Any advice/guidance would be much appreciated.

 

FYI…. My GTI is a Sofar 2200TL-G3

[Muhendis]

The most obvious way would be to disconnect the utility supply at the incoming isolator and see if you are sending anything out from the inverter.

With no utility supply present there should be nothing on the utility supply output from the inverter.

Your house supply should be unaffected. 

[Crossy]

Yeah, opening your incoming breaker would be the simplest way of checking that your GTI does indeed cut off in the absence of a mains supply.

 

Of course, if it doesn't cut off you have a potential issue!

 

Both of our Sofar inverters are pretty enthusiastic about dropping off on grid disturbances, the current favourite being "under frequency".

 

Check the inverter logs on your app, you should be able to see the power failure and when the juice returned.

[007 RED]

@Muhendis & @Crossy

 

Many thanks both for your suggestions. I'll test the inverter later this morning once the sun comes up.

 

FYI.... I've looked at the inverter's log on the app and it does show a big output power drop, but not down to zero. Bearing in mind the monitoring facility only collects data every 15 minutes, so not sure if it's a problem or not.

 

Will let you know what happens when l do the test you suggest.

 

Once again, many thanks.

[BritManToo]

13 hours ago, 007 RED said:

My question being, is there any simple way to test the anti islanding protection is functioning correctly?

Turn a light on when your grid power is out.

If it comes on, you ain't protected.

[Muhendis]

One scary idea has occurred to me.

Are you certain that your house supply is properly connected only to the house and not to the utility supply?

[007 RED]

2 minutes ago, Muhendis said:

One scary idea has occurred to me.

Are you certain that your house supply is properly connected only to the house and not to the utility supply?

Could you please expand for the dumb like me as l automatically assume that my house is connected to the utility - PEA. Thanks

[Muhendis]

38 minutes ago, 007 RED said:

Could you please expand for the dumb like me as l automatically assume that my house is connected to the utility - PEA. Thanks

My scary idea was with reference to the output of the inverter "house supply is properly connected only to the house" should have read "house supply from the inverter, is properly connected only to the house".

 

My mind is currently full of visa extension thoughts today so some of the information got missed out.

[007 RED]

14 minutes ago, Muhendis said:

My scary idea was with reference to the output of the inverter "house supply is properly connected only to the house" should have read "house supply from the inverter, is properly connected only to the house".

 

My mind is currently full of visa extension thoughts today so some of the information got missed out.

Many thanks.... Yes, I can confirm 100% that the GTI is connected directly to the house supply.  I've just done a test as suggested - results in next post.

 

Good luck with your extension.

[Muhendis]

17 minutes ago, 007 RED said:

Good luck with your extension.

Thanks. ????

[007 RED]

@Crossy ; @Muhendis ; @BritManToo

 

FYI.... I did the test that you suggested e.g. turning off the grid supply to the GTI.  In my case, the car port has a separate isolator which is between the house consumer unit and the power points, lights, CCTV cameras and GTI within the car port area.

 

I checked my system's monitoring facility app and at approx. 07:35 it was showing that the system was producing 0.13kW.  I also connected my Avometer to one of the power points in the car port area, and as expected it read approximately 220V (AC).   

 

I then shut off the isolator (between house and car port) and instantly the Avometer dropped to zero volts AC.  The system's monitoring app also showed that the output power from the GTI was zero as may be seen in the graph below.  The System's Alert facility was showing fault code "GridUVP" which denotes that the "electric grid is abnormal".

 

On turning the isolator back on, the Avometer returned to 220V (AC) and the GTI went into its normal start up mode.  After a minute or so the system monitoring app showed that the system was outputting power again, as seen in the graph below.

 

 

Initial conclusion.... The anti islanding protection appears to be working correctly and therefore I can only think that either my eyes were deceiving me yesterday when I though that I saw the disc spinning backward or in fact the grid power had come back on whilst I was outside the house and the GTI had re-established power output.

 

Obviously I'm going to monitor the situation to ensure that if the grid does go off my system does not feed anything back into the grid.

 

Once again, many thanks for your advice/assistance.

[Crossy]

Yup, looks like it's behaving as expected ????

 

[007 RED]

40 minutes ago, Crossy said:

Yup, looks like it's behaving as expected ????

 

I'm just a little concerned as to why the system log didn't register the grid power out yesterday morning (03/03/22). 

 

It was definitely a grid power out - fan stopped, TV turned off, water pump stopped and CCTV recorder/cameras went off.  As can be seen from the system's monitoring facility output graph below the power output dropped to zero at 09:18 yesterday (03/03/22).

 

 

I can't put this down to the old age thing (hopefully).  So a complete mystery for the time being ????.

 

Again, thanks for your support ????

[Crossy]

Which Sofar app are you using?

 

I have SmartClient which logs every 5 minutes or so, but it definitely misses short duration dips. The only thing you see in the log is that the inverter status is "Wait" whilst it sorts itself out.

 

The hybrid has a local log at the inverter, but I don't think the pure GTI has.

 

[007 RED]

1 hour ago, Crossy said:

Which Sofar app are you using?

 

I have SmartClient which logs every 5 minutes or so, but it definitely misses short duration dips. The only thing you see in the log is that the inverter status is "Wait" whilst it sorts itself out.

 

They hybrid has a local log at the inverter, but I don't think the pure GTI has.

 

On my PC it's SOLARMAN Smart Web.... and on the mobile it's SOLARMAN Smart App.

 

Looking at the downloaded data, it appears that the monitoring system interrogates the inverter about every 15 minutes.  That said, sometimes it takes a reading every 5 or 10 minutes.   There does not appear to be any means of adjusting the timing via the apps.  I suspect there may be something in the inverter setting that may allow the default timing to be changed, but as it is at present I'm OK with as it gives me a reasonable over view of the system's performance.

 

According to the user manual, my GTI does have an "Event List" which it says will show the real time event records and history.  The only trouble (for me that is) is that the inverter is mounted high up under the apex of the car port roof. 

 

 

This means standing on a ladder and fiddling with the silly button to the right of the display screen - long press - short press and stupid 0001 password every step of the way.  I'm not sure if interrogating the inverter log up there will give me any more info than I can derive from the app.

 

I think that I will do a few more tests like I did this morning, over the next week or so,  just to reassure myself that the anti islanding protection is working when the grid power is cut off.  Better safe than sorry!

[Crossy]

21 minutes ago, 007 RED said:

This means standing on a ladder and fiddling with the silly button

 

Yeah, I needs steps too although the regular 3 step kitchen thingy does the trick.

 

My GTI menu is in Chinese so never bother looking at it (inverter is a mainland China only version).

[007 RED]

11 minutes ago, Crossy said:

My GTI menu is in Chinese so never bother looking at it (inverter is a mainland China only version).

Of course you could always have a bit of fun and use your mobile phone translator App ????

[Crossy]

Just now, 007 RED said:

Of course you could always have a bit of fun and use your mobile phone translator App ????

 

Yeah, did that with the manual to get the beast set up, never bothered with the logs and stuff.