To work out the current, you need the power factor (and efficiency if it is a motors, as your kW is the output power):
Current = 530,000/(3x230xpower factor), at a power factor of 0.95 = 808 A
To understand the calculation, you can read the post: Three Phase Current - Simple Calculation
The cable size depends on the installation method and what voltage drop you will accept.
You can use the sites cable sizing tool to work this out.