Hi, glad to explain
Harmonics in layman’s terms : Bacteria or germs that appear under the microscope of a unhealthy blood sample.
Any signal that travels at frequency which is diffrent from the system fundamnetal frequency is a harmonic. In a 50 Hz system a 60Hz current is considred a harmonic. On the contrary, a 50 HZ current is considred a harmonic in 60HZ system.
Voltage harmonics generally increase transfomer’s eddy losses, overload capacitors ” can be RFI caps at the input of VFDs.
while current harmonics increase heat losses as voltage drop across transfomers windings as well resonance in capcitor banks.
the best approach in manging harmonics in a multi VFD installation is to use line reactros , this should probaply fix 60% of the problem then adecision will have to be made to apply a suitable harmonic mitigation technique. From My experience assuming the VFDs donot have line reactors , the reactors should significantly rectify the problem.