A clear distinction to measure the harmonic contribution of the multiple nonlinear loads on point of common coupling of the power grid is important to achieve the division of responsibilities of the multi harmonic sources. The paper first uses the fluctuation method to transfer single phase uncontrolled rectifier circuit to Norton equivalent model. Demonstrate the validity of the Norton equivalent model by comparing the value of harmonic current source and single-phase controlled rectifier circuit. Values of them are approximately equal. Then it sets up a circuit contains three harmonic sources and draw the Norton equivalent model of it. Finally, the paper calculates values of each harmonic voltage of every nonlinear load by using the equivalent impedance and uses voltage harmonic responsibility index factor dividing the responsibility of multi harmonic sources. This method is simple and effective and it is also conducive to the practical application of distribution network with multi harmonic sources responsibility division.
