Harmonic source tracing of distribution network is the base of harmonic management and pollution responsibility evaluation.In this paper

basing on three types of typical conditions of equivalent circuit and harmonic existence of distribution network

and take the public connection point of the single user and power supply system as the boundary

the relationship between harmonic power and harmonic pollution source across public connection point is analyzed

pointing out that the flow of single harmonic active power reflects location of harmonic pollution source in distribution network.Considering timevarying characteristics of the harmonic sources

a method of harmonic source tracing based on single harmonic net energy and total harmonic net energy is proposed.