Note: I recommend you use this addon instead: CustomPlayerPowerBarAlt/
That one will display a bar with numerical values where you can alter the font/bar style/etc.
If however you do like the standard Blizzard frame (I meanwhile do for the Fireland encounters!), I recommend BetterPowerBarAlt, which is still actively maintained.
I'm not entirely sure, but this addon here might not work 100% anymore. It didn't seem to save positioning after relogging, but that may have been a side effect of another addon interfering with the PlayerPowerBarAlt frame (namely Chinchilla). I haven't done extensive testing since I've found BetterPowerBarAlt to be superior.
This lets you move your PlayerPowerBarAlt frame, which is used in encounters like Atramedes or Cho'gall.
Usage: /movepowerbaralt or /moveplayerpowerbaralt or /mpba
You'll then see a light blue blox (see image), which represents the location of the PlayerPowerBarAlt frame. Left click and drag it to your liking, issue the command line again to hide the frame.
The first time you use this addon, the blue box will appear in the bottom center region of your UI. Many people will have other addons there (unit frames, grid, action bars), so you temporarily might have to disable/hide/move these or look closely to click the box to be dragged.