Mark,
Since what I mainly do is small wind related, this thread has me a
little concerened. Is this application receiving AC in a' la SunnyIsland
style, via another grid-tie inverter, or is the battery being charged
via a charge controller? Lacking theSMA technology that controlls
battery voltage and the "sell" function in a little different way,
shouldn't this system be configured in the second manner, that is
charging the batteries through a charge controller and diversion
resistor? If it were set up this way, would you still have this problem,
or is the battery just so small that the voltage falls precipitously as
soon as sell kicks in? I thought that there is a 5 minute wait period
prior to connecting to the grid anyhow, so shouldn't things even out
during that hysteresis?
Is there a configurable setting on the sell function that might allow
some lattitude in the amps going to the grid, or is it pedal to the
metal, regardless? If there is no control over the sell amps, seems to
me that would be a good idea.
Matt T
Mark Edmunds wrote:
Hi Wrenches -
Just to clarify on this a bit... When we designed the XW we were
always assuming there would be some sort of voltage regulation on the
input to the batteries, either with a PV MPPT controller or a
diversion regulator for wind and uHydro systems. So hence while the
unit does try to regulate the battery voltage while selling power to
the grid it does take some time when in sell mode to make sure
everything is stable and compliant with the UL1741 limits before
actually starting to transfer power.
With a typical set up this is just fine, but obviously with a wind
system like this the delay allows the voltage to rise to the point the
inverter thinks it has a lot of power to sell, and with smaller
battery bank sizes quickly pulls the voltage back down to the point it
stops selling.
As mentioned below we think we can speed this start of selling to the
grid when battery voltage rises past the Grid Support Voltage setting,
which should help smooth out this sort of situation. Initially we will
test this in the lab and at a few sites to ensure we get good
performance, then will roll the change into new units. This all may
take longer than a few weeks, but we will do our best!
Yours for a windy future...
Mark
Mark Edmunds
Director Engineering
Residential Renewable Energy Markets
Xantrex Technology Inc.
p. 604.422.2609
f. 604.420.1591
E-mail: mark.edmu...@xantrex.com
Website:_ _www.xantrex.com <http://www.xantrex.com>
*From:* re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*Michael Welch
*Sent:* Friday, January 16, 2009 1:46 PM
*To:* re-wrenches@lists.re-wrenches.org
*Subject:* [RE-wrenches] XW / Wind problem to be fixed by firmware update
Hi gang. Please contact me OFF LIST if you have any questions.
Dan Lennox asked me to post this to the list:
I have been working with Xantrex customer support for the last couple
of months, concerning an issue when a XW-6048 inverter is connected to
a wind turbine and allows alarmingly high battery voltage.
The inverter Grid Support Volts is set to 55v, and should sell at or
around this voltage. However I have seen issues where the inverter is
not selling and allows the battery voltage to get alarmingly high
(>60v). It would have gone higher (and I have seen 63v) except that my
diversion controller kicks in and diverts power, stopping the voltage
increase.
This situation occurs typically under low wind conditions and it
seemed to take about 15 seconds for the inverter to wake up and load
the wind turbine. When the inverter did 'kick in' it put a 60amp load
onto the turbine, which caused it to slow down, quickly lowering the
battery voltage and the inverter stops selling - causing the whole
cycle to happen over again!
I just heard from an Xantrex customer support engineer that the XW
inverter software has a built in 20 second delay (de-bouncing time
they called it) once the Grid Support Voltage is reached, regardless
of how high the voltage may get.
Xantrex has agreed to work on a firmware upgrade that will allow SELL
to occur when BATTV=GSV+4V and this should be available in a few weeks.
Dan Lenox
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