Difference between revisions of "Simple gas turbine control"

Revision as of 06:51, 31 October 2016

Someone asked how to create a simple gas turbine control.

Here's a simple dump from IRC, that still needs to be refactored, and images imported.

<kim_> you can actually pretty much run a gas turbine without anything fancy
<kim_> you may need a signal processor though
<kim_> the question is ... did I actually take screenshots of my simplest setup ...
<kim_> and.... I didn't
<kim_> ... yet
<kim_> ********: So part of the fun of the gas turbine is figuring it out for yourself ;-)
<kim_> So... you'
<kim_> ll need a few electrical probes ...
<kim_> Ok, anyway, you might need a few signal processors
<kim_> but nothing much beyond  A * B * C

<kim_> Ok, this looks a bit complicated, but bear with me
<kim_> it's really a few simple subsystems
<kim_> you might be able to make it simpler
<kim_> To begin with ... a gas generator can't start by itself. It needs a starter.
<kim_> https://imgur.com/RCXCiO6.png

<kim_> So your old 200V setup can do that
<kim_> just step up the voltage to 3200V
<kim_> so generators will generate electricity when they spin ...
<kim_> but they also work backwards: you can apply power to spin them up

<kim_> once you get the turbine+ generators over 200 RPM, (and ensure the turbine gets fed some form of fuel like syngas)
<kim_> it'll spin up just fine
<kim_> problem is, it'll KEEP spinning up
<kim_> by default, it's set to full throttle, and ... yeah... it'll overspeed and BOOM

</pre> <kim_> So ... <kim_> the simplest thing you can do ... <kim_> 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. <kim_> optimal voltage is 3200V at 800RPM <kim_> so we can just put a probe on the line and measure that <kim_> https://imgur.com/9a3k58d.png <- better version of last screenshot <kim_> note that 3160V in this example gives 100% input, and 3250V gives 0% output <kim_> err 3160V in this example gives 100% output <kim_> 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 <kim_> this ain't the prettiest, but it works <kim_> So... There's still some things that can go wrong in this situation. but the turbine won't just asplode in your face ;-) <kim_> ---------------------------------- <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_> https://imgur.com/JYIdKDb.png <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_> https://imgur.com/kCbAlIa.png <kim_> https://imgur.com/2zRzx4r.png <kim_> ... and that's the most complex logic you need to do :-P <kim_> === === === <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_> * Erisia-14 * Kim_Bruning just uploaded a screenshot: https://imgur.com/GY8xQFq.png <kim_> * Erisia-14 * Kim_Bruning just uploaded a screenshot: https://imgur.com/0n2BMlK.png <kim_> * Erisia-14 * Kim_Bruning just uploaded a screenshot: https://imgur.com/IcXh3wL.png <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) <kim_> https://imgur.com/d8RaHTP.png </pre>