Passive Power Filters Optimization In Traction Power Supply System Based On Modal Sensitive Analysis

With the development of Chinese needs of transportation, the high speed railway has the advantages of large transport capacity, little pollution and so on. Therefore the high speed railway is been promoted widespread. By the end of 2014, the railway mileage will reached 112 thousand kilometers, which the high speed railway mileage reached 16 thousand kilometers. The safety of the traction power supply system is the foundation of the safe and reliable operation of the high speed railway, but the harmonic problems is one of the threats to the safe and reliable operation of the high speed railway. Harmonic is not only easily led to explosion of the capacitive equipment, but also easily cause the EMU. Therefore, the harmonic has become main factor that affect the safe and reliable operation of the high speed railway.The harmonic problems can be classified into three types:(1) the background harmonic from the power supply system; (2) low-order harmonic emitted by the locomotive cause the parallel harmonic resonance occurs in the traction power supply system; (3) high-order emitted by the locomotive will increase the THD in the traction power supple system.The object of this thesis is traction power supply system of the high speed railway. This thesis is focus on the harmonic problems in the traction power supply system, and by using the filters to fix the harmonic problems.The thesis take the type of CRH380A locomotive as an example, based on the field measured data, study the characteristic of the harmonic emitted by the locomotive under different conditions. The harmonic currents distribution share the same characteristic under the traction conditions and regenerative braking conditions, which the locomotive can be equivalent to harmonic currents source.By establishing multi-conductor transmission line model. Based on the harmonic currents distribution of the CRH380A locomotive and modal analysis and harmonic resonance frequency sensitivity analysis, this thesis seek the harmonic problems and harmonic resonance frequency and the modal frequency sensitivity values of the traction power supply system. Reaching the conclusion:the harmonic resonance frequency is the intrinsic characteristic, which does not change with change of external conditions; the level of harmonic voltage in each substation of the traction power supply system is related to the numbers of the locomotives and the position of the locomotives.This thesis analyzes the impedance-frequency characteristics of the passive power filters, quality factor and the tuning frequency (cut-off frequency). Based on the foundation of combinations of single filters and high-pass filters. Based on the simulation analysis in different combinations of filters, one can reach the conclusion:the optimum filter combinations is the combination of the single-tuned filter and C-type high-pass filter. Finally, taking the an actual line as an example, based on the former methods, one can work out the harmonic resonance frequency, the frequency sensitivity values and the participation factors of the key nodes. According to the information, an optimization combination of filters, installation location and parameter settings of filters can be done. Ultimately, a suppression of harmonic and harmonic resonance plan for the actual line can be work out and proposed a relatively complete set of passive filter parameters designing process.