The Research On Harmonic Source Model Of Electrified Railway Traction Load

Electrified railroads in our country have quickly developed and have amounted to 30% of whole railroads. The electrified railroads that undertake 50% of total transportations bring a great benefit to national economy. However, a large amount of harmonic and negative is generated in the power network when the electrified railroads loads consume fundamental frequency electric power. At present, the electrified railway traction power system loads has become the most important harmonic source and negative sequence source, and they has caused serious harm to the power system and electrical equipments. For example, harmonic current cause the generators, electric motors have an additional power loss and heat; Parallel capacitance compensation device overload even damage; affected the precision of measuring instruments. Particularly, the combined effect of the harmonic and negative sequence enable relay and automatic device palpation, endanger the safety and stability of power system operation.It is necessary to study the content and distribute of harmonics current in order to alleviate their harms to traction power system's component, equipments of protect and measure as well as other customer's electronics equipment. Based on the circuit, electromagnetism and electric power electronics theories, computer technology, we have obtained various conditions'electric locomotive harmonic characteristics of run-time parameters. First, using matlab simulink toolbox strut the electric locomotive main circuit, auxiliary circuit and traction substation main transformer model of ss-8 electric locomotive separately. According the study in rectifier voltage regulator circuit and conduction process turn-on situation under traction working condition and braking condition, get it's operating characteristics of different operating environment such as different load, different slope and wind. Collect relevant data. Then analyze the electric locomotive's harmonic current imposed on the public power system under two supply arm one working and two working conditions of different transformers, also analyze the degree of asymmetry. A new simplified harmonic source model is proposed .This model use the harmonic current describe the harmonic characteristics of electrified railway traction load. In this model, the real and imaginary parts of harmonic currents are modeled by polynomials of fundamental's positive sequence voltage and current's RMS and the phase angle between them. Demonstrated the correctness of the model from the aspects of correlation analysis principle such as correlation coefficient, significant model equations, parameters and model significant and independent variables'chosen.Written the Asymmetric flow calculation procedure which include electrified railway traction loads. Solve the linear equation only if obtain the harmonic admittance matrix by lines, generators, transformers, load and other components'harmonic model. So the impact of traction load harmonic to public power system can be quantitative described by each node's harmonic voltage value.