Research On Electric Railway Power Quality Evaluation Method

In recent years, with rapid development of economy and science technology, the requirement to railway transportation is getting more and more important. As electric railway has many advantages, such as lower energy consumption, lower pollution to environment and lower cost, it is developed very fast in our country.In this paper, electrified railway traction power supply system for the object, study and analyze the characteristics of electrified railway traction loads, and on this basis to start to discuss several important electrified railway power quality parameters measurement theory and algorithms, the final assessment of the individual indicators based on the use of comprehensive integrated power quality weighting method for comprehensive evaluation.This paper describes and analyzes the composition and electrified railway traction power supply system load characteristics. From the electrical characteristics of electric locomotives, railway line conditions and factors transport organization and other aspects of the program analyzes the characteristics of traction load to verify the electrified railway traction load has asymmetric, nonlinear, volatility and high power characteristics. Finally, the focus on the characteristics of electrified railway to the harmonics, phase unbalance, voltage deviation, frequency deviation and voltage fluctuation and flicker several key individual indicators.In this paper, based on short-time Fourier transform is then discussed and studied several key indicators of electrified railway power quality detection algorithms, and design simulation experiments show the feasibility and effectiveness of the algorithm. On the selection window function, the paper compares several common window function applied to the power signal simulation results, the final choice of self convolution rectangular window, and select the time window width is automatically adapted to the signal frequency.Finally, for the evaluation process to determine the weight indicator system to this problem, proposed the introduction of a comprehensive approach to empower power quality integrated assessment models, the introduction of subjective and objective weight categories to determine each method and the use of G1entropy method, and finally multiplication based comprehensive integration subjective and objective weights weight combination weighting method to obtain comprehensive weight.