Background info:
I was building a station similar to how the iss was built. So I added module by module. I placed a control module, with a drone core, lots of RCS fuel and SAS modules. After that I added a module where crew can live, with a bunch of science experiments. And the last component I added before this happend were the solar panels themselves.
Because I wanted such big arrays, I didn't launch everything attached. I had two poles with the solar panels, and a base that had three docking ports. One medium, to attatch to the space station, and two small for the solar panels. All three units had drone cores, RCS Control and small solar panels so I could fly them to their destination.
Problem:
After I managed to add the solar panels succesfully, everything worked just fine. All physics were fine, and power was coming in. but when I exited KSP and loaded the save the following day to add the next component, all those solar panels started to freak out. I managed to close KSP with task manager before it saved, so I can make a video about it, and here it is:
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As you can see on the map the next module was very close to the station, and then I noticed the solar panels doing it, because when I was further away physics weren't applied to it.
Sorry this got a bit long. But does anyone know what is happening here and how should I handle this? (turning off or on SAS and RCS does not work).
Best Answer
SAS is your problem. If you turn it off, the oscillations should die out eventually. Additionally, you should be able to stop the oscillations using the time acceleration trick. The reason that the oscillations are increasing to destructive levels is that the parameters that control the SAS module are tuned to the natural resonance frequency of the station such that corrections are causing a positive feedback on the motion. Unfortunately, there isn't a way in the stock game to tune the parameters for optimal performance (what is known in control system parlance as critically-damped).
There is hope though. If you're using the Kerbal Attachment System (KAS) and Kerbal Inventory System (KIS) mods (they're best installed as a pair, but KAS is the only one you really need), you can attach struts to stiffen the solar panel beam relative to the rest of the station. Additionally, you can also change the resonant frequency of your station by adding to it. In particular, structures extending from the problem axis (in this case, the roll axis) will have the most effect.
Also, I can't tell if this is the case or not, but you only want a single SAS module active at any time on a non-rigid structure, or at the very least, have all the SAS modules on a single subsection of the station. At the very least, this will reduce the torque that's applied to the station, reducing the possibility of having an undamped system.