The absolute most accurate method is to perform a power analysis and create a computer model. The power analysis defines the entire electrical sysem from the utility to the loads. It is also very expensive and takes an fairly long time to complete.
Schneider Electric have developed an active harmonic filter selection tool that uses some approximations to short cut the above time and costs and provide an accurate solution. The tool includes guidelines and ‘best practices’ discussions to help you install the optimum equipment for best results in harmonic current elimination.
Using that tool and the information provided, yields the following provided the VFD and UPS have 3 to 5% impedance inductoance installed either on the mains (3-phase line reactor) or DC bus chokes. The TDD is calculated at 238 amps of rms harmonic current = 30.87% TDD. So, you need an active harmonic filter that is rated 1.2 x 238 = 286 amps.
Quick solution no cost invovled. But you need to be sure the inductors are present or a 300 amp active filter will not provide the beenfits expected.
Contact your local Schneider Electric representative for local assistance.
Rgerads and good luck,