Because of the random of the harmonics recourses in power system, it's necessary to analyze and estimate the random harmonic vector by using the method of probability and statistics. This paper Summed up the advantages and disadvantages of the existing method of multi-harmonic source summation, then presents a new method to obtain the sum of random harmonic vectors that have different phase angle probability distribution functions in a power system. Several vectors (voltage or current) are decomposed with X -Y axis. The probability density functions of the sum can be obtained by using Gaussian mixture models. The probability value of harmonic currents at 95% can be estimated also. SS6B electric locomotive model has been established based on PSCAD/EMTDC, the model solve the problem of establishing different simulation model in different running time, locomotive can be controlled by changing the level and speed. Harmonic current generated by the Electric arc furnaces and traction load have been summated, the result obtained by using Gaussian mixture model are consistent with the testing data, the efficiency of the proposed method has been proved.
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