You could do something like this:
Context: State --> Power --> Power --> Any
Optional:
Context: Time 08:00 - 17:00 (or whenever your work hours are if you
only want this to happen at work)
Context: Day M,T,W,Th,F (or whenever else you work if it's regular
hours if you want it at work)
Context: Location Work Location (if you want to use location if you
work weird days/hours... this will/can drain battery though)
Enter Task: Display --> Display Timeout --> 23 hours (or something
else high enough that it will stay on)
If you want it reversed when you unplug the phone then you can add
another profile like this (you could also use an exit task if you
didn't specify other context at the start):
Context: State --> Power --> Power --> Any (click the check mark
beside Invert to make the trigger actuate as soon as the phone is
unplugged)
Enter Task: Display --> Display Timeout -->30 seconds (or whatever
else you want this to be set to normally)