The calculation of system harmonic impedance is an important prerequisite for the evaluation of harmonic emission level

harmonic responsibility classification as well as the design of harmonic control device. In view of the least square linear regression algorithm for harmonic impedance

in this paper

its error generation mechanism and influence factors etc are analyzed and on the basis of the least square linear regression algorithm

the measurement error in both voltage and current are considered comprehensively

the coefficient matrix is optimized and a kind of calculation method of system harmonic impedance based on mixed total least squares with more accurate estimation result is proposed. Finally

the IEEE 14 nodes simulation model based on PSCAD is set up and the efficiency and correctness of the proposed method is verified by way of the result of the traditional method and the method in this paper.