The control station is for management only, so removing the power to it will not effect your NFS data.  You will simply not be able to manage the array until the control station is back up and running.  Run /sbin/halt to gracefully shut it down.
I have an NX4 with 3 DAE's.  Most of this is power redundant except for the control station.  I am working on balancing the load across the two different legs of the UPS and one of the PDU's the control station is on needs to be moved to another circuit.  What is the effect of this in terms of the NX4 serving NFS data to vmware hosts and replicating?  Should I log into the control station and do a shutdown?  Just a standard shutdown -h now, or is there another procedure.    I should be able to do this non disruptively as the other devices on this PDU have second power supplies on another PDU.  The control station however only has one power supply.  Thanks for the insight. 
Move NX4 control station to another power circuit.