[RE-wrenches] Enphase "AC Frequency out of Range"

Kent Osterberg kent at coveoregon.com
Thu Feb 7 10:21:35 PST 2013


The Aclara <http://www.aclaratech.com> TWACS 
<http://www.aclaratech.com/AclaraPLS/pages/default.aspx> signal that 
knocks the Enphase inverters off line is difficult to capture because it 
only last a few seconds every time the meter replies to a ping or data 
request. I did manage to capture it using Zelscope 
<http://www.zelscope.com/> with a long recording time. The attached 
image shows a pulse at the zero crossing of the ac waveform; some 
crossings don't have a pulse  - I think that is a binary zero and the 
pulse represents a one. The pulse does not change the ac frequency and 
has only a negligible effect on the rms ac voltage. However, the time 
between zero crossings is not always 16.67 ms.

Messing with the zero crossing like that is an ugly thing to do to the 
ac voltage. Many things other than inverters can be messed up by this. 
It caused one of my digital clocks to run fast. Our local utility has 
had complaints about numerous other devices that it has messed up. I've 
got some SunnyBoy systems with remote monitoring that don't seem to be 
bothered by this signal. The Enphase inverters do not tolerate it. I'm 
glad to hear that Enphase is working on a fix and hope that it is rolled 
out soon.

Kent Osterberg
Blue Mountain Solar, Inc.
www.bluemountainsolar.com

On 2/5/2013 2:38 PM, Nick Soleil wrote:
> Hi wrenches,
>
> The frequency out of range issue is being caused by some utility 
> meter's communication "ping".  This ping is actually affecting the 
> utility voltage and frequency, and can be viewed with a power quality 
> analyzer.  It is highly likely that this is affecting a wide variety 
> of utility-interactive inverters, but is only noticeable with the 
> Enphase systems; due to the high level of visibility that our 
> Enlighten monitoring and reporting provides.
>
> These changes required that the software undergo a new certification 
> process. We have completed our CSA certification of the new software, 
> and are validating it's functionality before pushing out the solution 
> to our entire population of microinverters.  We are in the process of 
> beta testing the software fix, and are hoping to have this resolved in 
> February.
>
> Thank you for your patience as we work to resolve this issue.
>
>
> On Tue, Feb 5, 2013 at 9:24 AM, <penobscotsolar at midmaine.com 
> <mailto:penobscotsolar at midmaine.com>> wrote:
>
>     Dave,
>        It doesn't happen often, and the longest I've seen him stay
>     "down" is
>     about a half hour, but it seems to get progressively worse as time
>     goes
>     on for some reason (initially only the five minutes, but longer down
>     times lately). This particular customer is difficult and picky, to
>     boot. I hope yours is a bit kinder. Mine seems to think we did him an
>     injustice of monumental proportions.
>        We have had the utility out there logging events, meetings with the
>     utility and another solar company in Maine to discuss all this, and
>     have kept Enphase in the loop throughout. Enphase has responded in a
>     responsible and reasonable manner throughout.
>        If you want to discuss this with Enphase, call and ask for
>     Bret. He's
>     the engineer I previously dealt with, although he is second tier,
>     he is
>     accessible.
>
>
>
>
>     > Thanks Daryl. Does your system also sometimes stay off for
>     longer periods
>     > sometimes? My clients system can stay off for up to 64 minutes.
>     >
>     > Dave
>     >
>     > -----Original Message-----
>     > From: re-wrenches-bounces at lists.re-wrenches.org
>     <mailto:re-wrenches-bounces at lists.re-wrenches.org>
>     > [mailto:re-wrenches-bounces at lists.re-wrenches.org
>     <mailto:re-wrenches-bounces at lists.re-wrenches.org>] On Behalf Of
>     > penobscotsolar at midmaine.com <mailto:penobscotsolar at midmaine.com>
>     > Sent: Tuesday, February 05, 2013 12:01 PM
>     > To: RE-wrenches
>     > Subject: Re: [RE-wrenches] Enphase "AC Frequency out of Range"
>     >
>     > Dave,
>     >   We have been having the same problem with an Enphase system in
>     Maine. I
>     > have been dealing directly with the third tier engineers at
>     Enphase and
>     > they
>     > are working on a software fix for this. The"event" itself is only a
>     > fraction
>     > of a second but IEEE requirements are that the inverter shut
>     down for five
>     > minutes. I only found out about this problem when it started for
>     this
>     > customer. It sems that Enphase has already addressed the problem
>     with a
>     > software fix for the M-190's. The M-215 fix should come,
>     according to
>     > Enphase, by the end of March. It will be automatically
>     downloaded through
>     > the Enlighten router.
>     >    It's a known issue with Smart Meters with Enphase, but should be
>     > reconciled soon.
>     >
>     > Daryl DeJoy
>     > NABCEP Certified PV installer
>     > Penobscot Solar Design
>     > www.penobscotsolar.com <http://www.penobscotsolar.com>
>     >
>     >
>     >
>     >> Wrenchsters,
>     >>
>     >>
>     >>
>     >> I have an Enphase 7.5kW system on a residence with utility Smart
>     >> Metering, both the PV Production Meter as well as the utility
>     billing
>     >> meter being "read" every hour. This system has experienced many "AC
>     >> Frequency Out Of Range" events since the system was installed.
>     Below
>     >> is copied the Enphase Event message. This particular event was
>     for 5
>     >> minutes. Most of the events (all events are AC Frequency Out Of
>     Range)
>     >> last 5 to 10 minutes but occasionally they have lasted from 45
>     minutes
>     >> to
>     > 64 minutes.
>     >>
>     >>
>     >>
>     >> My question is: Could the use of the smart metering increase the
>     >> likely hood that AC Frequency events happen? Or is this just a
>     >> coincidence and that we are dealing with fluctuating utility
>     power AC
>     >> Frequency issues?
>     >>
>     >>
>     >>
>     >> <<
>     >>
>     >>
>     >>
>     >> Started on: Mon February 04, 2013 12:49 PM EST
>     >>
>     >> Cleared on: Mon February 04, 2013 12:54 PM EST
>     >>
>     >>
>     >>
>     >> Recommended action
>     >>
>     >>
>     >>
>     >> This condition should correct itself. No action is required.
>     >>
>     >> Details
>     >>
>     >>
>     >>
>     >> The microinverter reports that the frequency coming from the
>     utility
>     >> is either too low or too high as specified by applicable regional
>     > standards.
>     >>
>     >>
>     >>
>     >> AC frequency is the frequency at which voltage varies on the
>     utility
>     >> grid.
>     >> Frequency Out of Range events are usually transient and
>     >> self-correcting by the utility.
>     >>
>     >>
>     >>
>     >> When the microinverter detects an out of frequency condition,
>     it must
>     >> remain offline until the utility has been within acceptable limits
>     >> continuously for a short period of time (seconds to minutes,
>     varies by
>     >> region). If during that time the utility again exceeds or falls
>     short
>     >> of acceptable limits, the five-minute timer must restart and the
>     >> microinverter may not begin producing power for an additional short
>     >> period following the last out-of-bounds condition.  >>
>     >>
>     >>
>     >>
>     >> Best,
>     >>
>     >> Dave
>     >>
>     >>
>     >>
>     >>
>     >>
>     >> David Palumbo
>     >>
>     >> Independent Power LLC
>     >>
>     >> 462 Solar Way Drive
>     >>
>     >> Hyde Park, VT 05655
>     >>
>     >> www.independentpowerllc.com <http://www.independentpowerllc.com>
>     >>
>     >> Vermont Solar Partner
>     >>
>     >> 25 Years Experience, (802) 888-7194 <tel:%28802%29%20888-7194>
>     >>
>     >>
>     >>
>
>
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