Nonlinear loads cause nonlinear distortion in the current withdrawn from the distribution station. The distorted sine waves with even symmetry have only odd harmonics such that:

i(t) = I1 sinwt + I3sin3wt + I5 sin 5wt + ......+ In sinnwt, with n is an odd number.

Due to the impedance of the transformer the harmonic currents cause harmonic voltage at the output of the transformer. Assuming the transformer impedance is Zt, then the terminal voltage will be v(t)= I(t) Zt= I1 Z1 sinwt + I2 Z2 sin2wt+..............+ In Zn sinnwt, where Zn is the transfromer impedance for the n th harmonics.

This is a simplified model to demonstrate the effect. Both the harmonic currents and voltages are standardized.

For more details please see the paper in the link:https://pure.strath.ac.uk/portal/files/12583986/C_2012_Carter_2012_EVS26_EV_ChargingHarmonics.pdf

Best wishes

Thanks a lot sir @ Abdelhalim Zekry