Assessment Method of Harmonic Emission Levels Based on Maximum Likelihood Estimation

Evaluating the harmonic emission levels on the customer side and utility side is significant for harmonic responsibility classification. This paper proposes a harmonic emission level assessment method based on the maximum likelihood estimation. By establishing a model for assessing harmonic emission levels, it is deduced that the key to assessing harmonic emission levels lies in the calculation of utility harmonic impedance. Through the study of harmonic data, we find that the utility harmonic impedance tends to conform to a particular distribution, varying with the harmonics of the point of common coupling and background harmonics. Therefore, we consider using the maximum likelihood estimation method to calculate the utility harmonic impedance and further obtain the harmonic emission levels on the customer side and utility side. Simulation and field-testing data verified the effectiveness and accuracy of the proposed method.