Climbing Vpv Input

[kitestrings]

Hi Folks,

Significant progress on our wind project this fall/winter.  We finally got things situated and the turbine now up on the permanent tower.  Here's a link to our project:
http://www.fieldlines.com/index.php/topic,149124.0.html

We're using two Classic 250's.  Had experienced some problems with the transition from one to the other early on, but I'm happy to report they are playing well together now; and a big thanks to Ryan & Roy for helping me work through that issue.

We are having one minor, different, issue.  When there is ample PV output, and no wind, the first Classic "A" (programmed for the low-end of the power curve) seems to be somehow picking up a higher Vinput reading.  I believe it is from the PV, because I recently saw it go to ~140V, with little wind, while Classic "B" was indicating only ~60V.  I think the only way this could happen is from the PV open circuit sweeps.

The PV charges off our original OB MX-60 controller.  The two Classics have (2) isolated rectifiers.  The only thing I could think of that was "in common" to both PV & Wind is the aux2 diversion still also had the original OB aux wires connected; though aux output has been OFF on the MX-60 since we put in the Classics (allowing PWM).  So, I've removed those control wires from the MX-60 to rule that out.  We'll see.

Any other ideas are welcome.

Kind regards & happy holidays. ~ks

[ClassicCrazy]

If you shut off the input breakers from your wind , do you still get the high voltage ? 
Any way here are AC wires somewhere are inducing voltage into the other wires ?

I looked at your link - that is a nice setup and location. Sure makes solar seem easy compared to hauling heavy stuff way up a heavy duty tower .

Larry

[kitestrings]

Hi Larry,

I haven't tried shutting off the input breakers, but I can.  What I have done is turned the Classic Mode to OFF (from Wind Mode).  When I turn it back on it goes back to normal, but I can't do this if there is wind. 

The simplest fix is to just turn Aux2 to Manual ON, on the Classic (A) that controls our load bank.  This essentially shorts the 3-phase leads - not a dead short, but it fully engages a wye configured resistor bank of about 3.4 ohms.  It goes away with this action.  It is not immediately as the unit "holds" the Vin reading for a bit with some sort of (I assume) averaging logic.

Both times I've noticed it has happening have been when I was doing equalization charges.  The first time I had an auxiliary generator charging, so there was AC at/into the inverter for charging.  Most recently we just had a nice sunny day; little or no wind and minimal load, if any on the inverter, but I'll explore that a bit more (proximity of AC).

~ks

[kitestrings]

You got me to thinking about this a bit more...

I've been leaning in a similar direction, that is, when I observed high input voltage initially I could quickly rule out the wind input being anywhere near that high - and even for the PV array it struck me as high.  Our nominal array voltage is 72V; Vmp is 97V; Voc is 122V (at 25C); and Voc_max is 152V (at -21C).  It's acting more like a 'phantom' power quality issue.

I got to thinking that the original Aux diversion control wire was routed thru the DC panel, but then goes above the inverter and AC terminal box in a piece of PVC flex conduit.  As I mentioned I've disconnected this wire, and today is a good day to check if anything changed.

Similarly, the DC input and output wires to the Classics are in another short run of conduit (non-metallic, unshielded), that travels above the inverter to get to the DC load panel.  If it happens again, I might try shutting off the inverter to see if anything changes.

I'll keep you posted.

[kitestrings]

Hi folks,

So, I'd removed the control signal wire from the OutBack MX60 and was thinking it was just that simple.  I actually haven't seen a repeat of the original reported issue.

This morning the wind was coming up strong, and I happened to be video recording the Classic output, when noticed a similar incident.  Picture this:

The input voltage to the Classic is running about 80-85V, the turbine is putting out 700-1,000w, the batteries are at 51.7V.  Arms reach next to me the MX60 is doing its morning routine, looking for enough light to start, sweeping the array every ~9-mins. IIRC.

In the next frame of the video - one frame only - the unit goes into Hyper Voc, the input voltage drops to 0.1V and the battery voltage displays 107.6V!  Wow!  I had briefly caught the change from MPPT to Hyper V, but had I not recorded it I would have missed it.

So, obviously the battery bank is not 107V, but somehow (I believe) when the PV controller goes open circuit on the array, the Classic is getting a brief glimpse of it.  Oh, I also snapped a picture of the PV voltage on the "resting" OB a minute later; "107V".

I'm still not sure what I can do...perhaps somehow shielding the PV input &/or output leads...metal conduit?  Puzzling.

[ClassicCrazy]

Maybe you can PM Ryan and ask him to take a look at this post - he may have some thoughts about this .

Larry

[Halfcrazy]

I truly doubt this is anything to do with the MX60, If the battery is showing 107 volts on that classic I am thinking it is 1 of 3 things in this order of likely hood:

1- Noise (Switching noise) is being introduced on comms cables and is confusing the multiplexer. Maybe you can give us an explanation of what is hooked to the classics for cables and where they may be routed.

2- A bad Multiplexer (This seems less likely as it would seem like it would show off all the time. I have seen this on 3-4 occasions now where all voltages basically double give or take but you said PV went to 0?)

3- A bad connection on the battery side some where and the classic is actually spiking to 107 (this seems VERY unlikely as the classic regulates super fast. If you open the battery breaker you will normally see it bounce maybe 1-2 tenths above the target then regulate perfectly)

If you could get some pictures of the classics with covers off starting backed out so the majority of the system is visible and then maybe a few close ups. You can email me directly vs posting them here.