[RE-wrenches] Anti-Islanding Explanantion

Tue Jul 26 10:38:27 PDT 2011

Peter,

Correct.  After a fault due to any utility protective function, the inverter must monitor the grid and all parameters must remain within acceptable limits for a default time of 300 seconds prior to reconnection and commencement of power export.  If, during the 300 second monitoring time, the utility goes out of spec, the timer must start over and begin a new countdown.  With utility authorization, the 300 second timer may be reduced to some other value acceptable to the utility protection engineer.

See ya!

Marv
Director of Technology and Support, North America
SolarEdge Technologies, Inc.
Tech Support Mobile:  +530.798.6770
Mobile: +530.392.0356

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Peter Parrish
Sent: Monday, July 25, 2011 8:50 AM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Anti-Islanding Explanantion

Thanks Marv.

For the purposes of explaining anti-islanding to non-technical people, I think the default frequency range of 59.3Hz to 60.5Hz, and the default voltage range is 88% to 110% of nominal is good for starters especially in the perspective of the initial start-up of a gird-tied PV system.

Just so I am completely sure of what you are saying: For a split phase
120/240 Vac, 60 Hz system...the PV system would connect to the grid if after
5 minutes the

The voltage window would be 105.6 Vac to 132 Vac, L1-N and L2-N.
And the frequency window would be 59.3 Hz to 60.5 Hz.

- Peter

 Peter T. Parrish, Ph.D., President
California Solar Engineering, Inc.
820 Cynthia Ave., Los Angeles, CA 90065
CA Lic. 854779, NABCEP Cert. 031806-26
peter.parrish at calsolareng.com
Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Marv Dargatz
Sent: Wednesday, July 20, 2011 11:11 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Anti-Islanding Explanantion

Wrenches,

I feel compelled to reply here, as I have personally performed all of these
tests and listed several dozen inverters over the last 10 years.

The "Utility-Interactive" marking on listed inverters means that they meet
all of the Utility Protective Function requirements as outlined in
IEEE1547.0, and have been tested in accordance with the procedures detailed
in IEEE1547.1.  Most of the functions have a threshold value and a response
time associated with them.

The Utility Protective Functions include:

Temperature stability
Abnormal voltage
Abnormal frequency
Synchronization
Interconnection Integrity
DC injection
Unintentional Islanding
Reverse Power
Open Phase
Reconnect after abnormal condition disconnect
Harmonics
Flicker

All of these tests must be performed using equipment that meets certain
accuracy requirements, and includes considerations for "manufacturer's
stated accuracy" of these functions.

In addition, there are utility related performance criteria in UL1741.  For
instance, during abnormal condition tests, the maximum fault current and
duration must be quantified and published as a rating.

Just to clarify some of what Peter wrote, the default frequency range is
59.3Hz to 60.5Hz, and the default voltage range is 88% to 110% of nominal.
The voltage must be measured from line to neutral if a neutral is present in
the connection (i.e. a Y transformer connection).  In addition, there are
outer boundaries that require faster trip times.

Bottom line is, if the inverter has a listing mark on it (UL, CSA, ETL, TUV,
etc) and is marked "Utility-Interactive" there should be little or no
question as to its' suitability for interconnection.

Hope this helps.

See ya!

Marv
Director of Technology and Support, North America
SolarEdge Technologies, Inc.
Tech Support Mobile:  +530.798.6770
Mobile: +530.392.0356

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of R Ray
Walters
Sent: Tuesday, July 19, 2011 10:44 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Anti-Islanding Explanantion

If you wouldn't mind Peter, I'd like to see this discussion stay on the
list.
I'd be interested to learn more about the actual anti-islanding features of
inverters.
What you've described seems to just cover the voltage and frequency windows
that the inverter will grid tie to.
I was always under the impression (perhaps false) that there were additional
software controls to prevent anti-islanding to another inverter.
Bill Brooks seems to know more about UL1741 test procedures.

R. Walters
ray at solarray.com
Solar Engineer

On Jul 19, 2011, at 10:04 AM, Peter Parrish wrote:

> I need to give a group of California educators the simplified
> explanation of inverter anti-islanding. I know the full details are
> quite complicated and have evolved a bit over the past few years, but
> would the following be an acceptable short explanation?
>
> *** Please contact me off-list with comments & edits. Thanks. ***
>
> This is an excerpt from a longer discussion about designing and
> installing grid-tied "Inverter anti-islanding is a requirement of the
> NEC and the Underwriter's Laboratory test procedures. A somewhat
> over-simplified version of "anti-islanding" says that if the grid
> voltage goes out of the range of 216 to 264 Vac or if the grid
> frequency goes out of the range 59.9 to 60.1 Hz, the inverter must
> shut down within one cycle (1/60th of a second). Once in this shutdown
> mode, the grid must come back into compliance (both frequency and
> voltage) for 5 continuous minutes before the inverter may turn on again.
> This is pretty "ho-hum". However, two of our laboratory sessions
> involve building a real, grid-connected PV system. So when our
> students go to turn on their system for the first time, they get to
> experience the "anti-islanding" function first hand."
>
> Peter T. Parrish, Ph.D., President
> California Solar Engineering, Inc.
> 820 Cynthia Ave., Los Angeles, CA 90065 CA Lic. 854779, NABCEP Cert.
> 031806-26 peter.parrish at calsolareng.com Ph 323-258-8883, Mobile
> 323-839-6108, Fax 323-258-8885
>
>
>
>
>
>
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