Zero reactive power function
Zero reactive power function
(OP)
Hello Eevryone!
I have come across one of a 'Zero reactive power function' while reviewing AVR document for 776MVA Generator. In AVR manual this functions is not described in detail.
After googling few websites I found this function is incorporated in Power controller(VAR controller for Power Plant) also which is used as Unload function.
I would be very much greatful if anybody clarify more about above mentioned function in this thread?
Thanks in advance!
I have come across one of a 'Zero reactive power function' while reviewing AVR document for 776MVA Generator. In AVR manual this functions is not described in detail.
After googling few websites I found this function is incorporated in Power controller(VAR controller for Power Plant) also which is used as Unload function.
I would be very much greatful if anybody clarify more about above mentioned function in this thread?
Thanks in advance!






RE: Zero reactive power function
RE: Zero reactive power function
tlrols,
there is separate power factor control function in addition to Zero reactive power command in AVR.
I have encountered this(Zero pf) command in 270MVA as well as 776MVA Generator. I am doubtfull if they are usually using this function.
RE: Zero reactive power function
RE: Zero reactive power function
the manual says that,
'An unloading facility is available
which, when activated, will reduce
the generator reactive power to
zero or the power factor to 1,0.'
perhaps it may be generator open condition.
thank you so much!
RE: Zero reactive power function
+1 on the system operator issue, AVR's are there for a reason. Fast cos-phi control response will handicap the ability of your generator on the power system.
RE: Zero reactive power function
esee135
What I understand is that before isolating generator from system during fault or shutdown condidions Zero reactive power function will be activated so that only active power current will be interupted by circuitbreaker,
Which can save wear on breaker.
One more question, is this function inbuilt in your AVR or it is separately incorporated in VAR controller?.
RE: Zero reactive power function
If you don't have it, you can do it with a PLC start/stop chain, or you could make a slow tuned outer closed loop that you unload watching MQ's and feed the AVR summing junction. That error would be available only during the shutdown sequence.
RE: Zero reactive power function
----
What I understand is that before isolating generator from system during fault or shutdown condidions Zero reactive power function will be activated so that only active power current will be interupted by circuitbreaker,"-----
static exciter shutdown during an 86 and during a controlled shutdown differ drastically. On 86, the bridge goes to negative retard, field breaker trips, and the crow bar asserts.
On a controlled shutdown (stop signal given), the field breaker usually stays closed, and the bridge goes to negative retard. Very different shutdown curves. Prior to this is where the pf unload would occur.
The difference is on a controlled situation you don't want the di/dt voltage on the rotor/causing havoc on the stator as well. Hence, negative forcing during shutdown to arrest the field current momentum.
RE: Zero reactive power function
Now my doubt is clear, with present 776MVA generator we have this function, I have investigated few older generator where this function is not there, as you suggested we can retrofit old AVR with new one.
RE: Zero reactive power function
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