Research On Harmonic Voltage Emission Limits Of Electric Traction Loads

More and more attentions are paid to harmonic problems of power systems. Traction loads of electric railways are paid importance as special harmonic distorting loads. The research about traction loads' harmonic emission limits of electric railways are also deeper and deeper.Firstly, this paper introduces the national and overseas background of researches about harmonic emission limits of electric railways briefly, some kinds of harmonic standards used in several countries, IEEE harmonic standards and IEC harmonic standards. Secondly, the paper mainly discusses harmonic transform models and their transform matrixes between three phases and two phases at several models of connection of traction substations, and transforms the primary and secondary electric values of traction substations based on the above researches. Thirdly, sub electric network of Xichang and the harmonic voltages' distorting levels of several traction substations are discussed and analyzed. At the same time, each harmonic voltage's distortion and the total harmonic voltage's distortion of the 110kV side and the 27.5kV side of traction substations are gained thorough calculating and analyzing the actual measure data. And each harmonic voltage's discrete figure is acquired, too.As for the special traction loads of electric railways, the paper uses the national harmonic standard GB/T 14549-93 Electric quality public梕lectric network harmonics and assessments of stage 2 and stage 3 mentioned in the national standardization guide technique document GB/Z 17625.4-2000 Electromagnetic compatibility: Assessment of emission limits for distorting loads in MV and HV power systems - Basic EMC publication to evaluate each harmonic voltage's emission limit and the total harmonic voltage distortion factor of Xichang sub electric network. The paper compares the super scales of each traction substation, which are evaluated in the two standards, and analyzes the rationalities of the two assessments. From these above researches, we can draw a conclusion that Xichang sub electric network is needed to be fathered and to be improved to reduce the harmonics by adopting the technique means or other measures.