Aurora control problem

[Dar Coo]

Hi everyone
My local power one guy is great but very hard to get contact with I think he is overworked so hope someone may be able to help me. I have a aurora inverter and turbine control on a 3 kw hydro turbine and have trouble with the controller failing. As I need to control overspin on power fail I have modified the activation voltage to activate at 320v. In normal operation the voltage is around 300v so when grid is lost the turbine speed is not a lot more than normal to activate the dump load. When grid is back on the change back is very smooth. Works great but second controller failed today. Before failure it started to clip the voltage at 305v then locked on with full diversion at any voltage and also still connected to the grid. Not good!!! Exactly what the first one did before failure.
With the diversion load disconnected the unit still runs fine. After failure today and dump disconnected ran the turbine flat out , harder than normal at generator output of 3100w from 3 kw unit at 1800rpm. So while happy with the P1 gear is it not up to the task of turbine control in it's true form?
Also can anyone explain the limiting indicator on the power curve page of aurora installer
Why it comes on and how do you get rid of it or program around it.
Hope someone may be able to assist.

[Rob Beckers]

Hi Dar,

Looks like you're familiar with AuroraInstaller: The 'limit' indicator comes on when the inverter runs into a hard limit, that's when either the input current or output power exceeds the limits for the inverter. Given your fairly high DC voltage the input current won't be an issue. For output power I don't know for sure where Power-One draws the line. The 3kW inverter is identical to their 4.2kW inverter, it is the firmware that limits the output and makes it a 3kW inverter. The wind inverters can be programmed to produce quite a bit more than 'rated' power (For the 6kW we routine program them to do 6.2kW, and some have run them to 6.9kW, I have not tested the 3kW enough to know where Power-One draws the line). You can try changing the curve and run it up to 4.2kW (still safe for the hardware), if the inverter limits output you'll see it, unless your hydro generator cuts out first.

Instead of the controller you're using to switch to dumpload you could just make your own using an Omron measurement relay and contactor. You can find a wiring diagram here (http://www.solacity.com/Docs/Wind%20Turbine%20Overvoltage%20Protection.pdf) that shows how it can be done (the wiring diagram has as its primary purpose to protect the inverter, but you'll get the general idea).

-RoB-

[Dar Coo]

Thanks Rob,
Yes many hours working out a power curve as unable to get one from the manufacturer. I was reasonably sure it was in the curve settings as had been running the last curve point at less than inverter capacity and put in last point at 500v 3600w today and hadn't hit the limiter when the controller failed all my input And output V and I are below the capacity of the inverter.
extended programming manuals are non existent and available ones very basic.
A voltage relay will be going in next week on the AC side pre the expensive aurora rectifier and connect to a 3 kw air cooled element.
Will investigate auto valve shut on power fail or inverter fault with the relay output in inverter and that will limit the use of the voltage relay and dump load, will just need to do manual restart after power outage.
Have you seen any controllers fail in a similar way to mine? I am injecting single phase AC up to 270v from turbine.