Correcting harmonics for power factor correction
Line reactors can be installed at the input to individual non-linear loads to reduce harmonic currents. Harmonic filters could also be used for individual non-linear loads.

Harmonic resonance in the power distribution system can be reduced by changing the natural frequency of the system, but that may be difficult to accomplish. The effects of harmonic currents in the distribution system can be reduced by installing harmonic traps. It may be possible to add reactors to system power factor capacitor banks to convert them to harmonic traps.

In systems where harmonic problems are evident, it will probably be necessary to perform a harmonic analysis of the entire system. You will need to find detailed reference material explaining how to perform an analysis and design or select a mitigation system.