How many Ahr rating on battery is enough to drive a load of 14MW.... If the required input voltage for the inverter is 1500vdc

 

If your batteries can deliver 9,333 Amperes for 1 hour that should do it.

 

How many Ahr rating on battery is enough to drive a load of 14MW.... If the required input voltage for the inverter is 1500vdc

For how long do you wish to drive the 14MW load? What type of battery?

 

The Ah rating of a battery determines how long it can deliver the current, not how much power it can provide.
14MW is a humongous load.