I work on wind turbines, I am a troubleshooter. I have a problem on the turbine which I cannot solve so far I would like to ask the help of this community.
When turbine starts to generate, an unbalance appears on the 690V 3-phase system. This appears only when the turbine is producing. The phases are balanced when the turbine runs from the grid.
As the generator production increases, the difference on phase 1 gets bigger. The maximum I've measured on phase 1 was 422V to ground. The other two phases are stable 397V.
In the line of the production there is the generator, converter AC/DC and DC/AC, main reactor, filter cabinet and the 690V circuit breaker.
My question is, what could cause this unbalance? If you need more info about the system, just let me know.