Harmonic Filter Sizing

I don't have a web site to point to but you are correct that the feeder impedance does affect the calculation of the filter components. This is especially important when the filter's capacity is many percent of the feeder's. In those cases, the feeder's inductance cannot be neglected.

Multi-harmonics filter banks are a pain to design and to maintain. When some capacitor begin to loose capacity from self-healing, the resonance frequency on the banks change and can cause big resonance at frequencies you didn't expect. You also have various inter-resonances problems and multitude parallel resonance frequency. This means that the filters can resonate with the feeder's distortions. This is usually a destructive situation.

Try to use only a de-tuned 5th harmonics filter. It might attenuate the higher components enough for your application. Keep it simple, and oversize your components.

We need to think from Source of Harmonic generation. We have to measure the harmonics to compensate it effectively. Since the harmonic compensation is expensive, it is good to measure and prepare goal & sollution with cost benefit analysis.

There are two sollutions avialable like tuned and active.

Usually active filters will compensate up to 50th Order. They have feedback loop and controls compensation in real time ( IGBT & DSP).

Tuned filters will be designed for particular tuned frequency ( what ever the order)and low cost. It is combination of L & C. Hence resonance will be problem. Maintenance and aging will affect the tuned frequency down the line.