What information is needed to size an Active Harmonic Filter

The following information is all required in order to correctly size an active harmonic filter:

One-line diagram of the system. Location and size of VFD’s and Power Factor Correction Capacitors is very useful.
Detailed equipment lists can also be used, especially in conjunction with one-line diagrams.
VFD information: Horse Power or Current size.
Are line reactors being used with each VFD? If so what is the impedance?
Will the active filters operate on generator?
Are there any large soft start loads located downstream of the AHF?
Local Environmental Conditions