Simple gas turbine control
Someone asked how to create a simple Gas turbine control.
Here's a simple dump from IRC with images inlined. This can serve as a placeholder until we have better documentation.
Click images for file info (and ability to zoom)
Getting it working
You can actually pretty much run a gas turbine without anything fancy. Part of the fun of the gas turbine is figuring it out for yourself ;-)
You will need a signal processor or two, but nothing more complicated than A * B * C.
Ok, this looks a bit complicated, but bear with me, it's really just a few simple subsystems. To begin with ... a gas generator can't start by itself. It needs a starter.
Your old 200V setup can do that, all you need to do is step up the voltage to 3200V using transformers. Generators will generate electricity when they spin ... but they also work backwards: you can apply power to spin them up.
Once you get the turbine and generators over 600 RPM (and ensure the turbine gets fed some form of fuel like syngas), it'll spin up just fine. Problem is, it'll KEEP spinning up. By default, it's set to full throttle, and ... yeah... it'll overspeed and BOOM!
So, the simplest thing you can do: the voltage and rpm are directly correlated. If the one goes up, the other goes up, and if the one goes down, the other goes down. The optimal voltage is 3200V at 800RPM (when not under load), so we can just put a probe on the line and measure that. Note that <3160V in this example gives 100% output, and >3250V gives 0% output. If we hook this up to the turbine with a signal wire, it'll control the throttle. If the turbine goes too fast, it'll be throttled down, if it's ok to go faster, it'll throttle up. It isn't the prettiest, but it works. So... There's still some things that can go wrong in this situation. but the turbine won't just asplode in your face ;-)
things that can go wrong
overamp
<kim_> ok, so 2 things that can go wrong ... <kim_> first thing is... the turbine+generators are very powerful. You can send more amps down the line than the line can handle, and it'll melt! <kim_> so maybe we want to control our turbine speed based on Amps?
<kim_> Well, we can have the best of both worlds , we can have the voltage based signal and amps based signal hooked up to a signal processor, and just do A*B (or whatever the 2 inputs are) <kim_> this works because we're multiplying % . If it's 100% ok to let the turbine run at a certain speed based on amps, and the turbine should be running at 60% due to volts, 100%*60%=60% <kim_> (or if you like proportional numbers, which is what the signal processor uses: 1.0*0.6 = 0.6 ... so no probs!) <kim_> ... if we're messing with a signal processor anyway, we can also add an on/off switch. 1= on, 0 = off. <kim_> same way... now we get A*B*C
<kim_> ... and that's the most complex logic you ''need'' to do :-P
inertia leads to overvolt
<kim_> The second thing that can go wrong is that the turbine has inertia <kim_> Say the breaker trips, even if we cut the throttle immediately, the turbine+generators keep spinning. <kim_> so they keep putting out power. But the power has nowhere to go ! <kim_> well... we'd better provide an emergency outlet.
<kim_> make a relay that dumps power to ground , and have it trigger if your voltage goes too high <kim_> *obviously* if you dump power direct to ground with no sort of resistance, That Would Be Dumb <kim_> so put a big resistor with cooling fins on top of there. (the large rheostat works fine)