Research Of Power Harmonic Measurement Method Based On Electrified Rrailway

According to the medium and long-term plan of the former Ministry of Railways on electrified railways,by 2020,the total length of electrified railways in the country will reach 72,000 kilometers.The development of electrified railways has become an important indicator of whether a country is now.Power grid harmonics are a type of pollution of electrical energy.In recent years,with the development of power electronic devices and the increase of railway locomotive power,it has gradually developed into a major source of harmonic pollution.However,due to the nonlinearity,randomness and impact of locomotive load,it is used in other applications.The harmonics generated by electrical equipment are very different,so the use of conventional harmonic measurement methods does not fully realize the detection of harmonics of electric iron.In order to find a suitable method for harmonic measurement of electric iron,the thesis studies the electrical harmonic measurement method of electrified railway,and uses LabVIEW simulation to test the content of harmonics and harmonic distortion rate THD of electric railway based on different measurement methods.The main research work is as follows:First,research on the background and significance of the thesis was carried out.Including the development and current status of harmonics in the public power grid;the three stages of harmonic measurement technology development and the direction of harmonic concentration research;the impact of electric iron on the harmonic measurement of electric energy is analyzed in detail,and the structure of the full text is rationalized at the end.sarrangement.Secondly,the electric iron harmonics were studied.Including harmonic definition and classification,the particularity of electric iron harmonics and the harm caused by electric iron harmonics to the safe operation of railways.Then,a detailed theoretical analysis of the measurement methods based on different algorithms of harmonics is carried out.Including fourier algorithm,instantaneous reactive power algorithm,wavelet transform algorithm and TLS-ESPRITS algorithm,and carry out detailed theoretical analysis and formula derivation for each algorithm,for the following harmonic measurement of different algorithms based on LabVIEW Management system design provides theoretical guidance.Finally,the Harmonic Measurement Management System was designed using LabVIEW tools.Including public module design and measurement module design,the common module is designed with system login program,data acquisition program,data storage program,data display program and historical data query display program.In order to achieve better test results,it is designed in the data acquisition part.Two acquisition modes,one is based on simulation data acquisition,one is based on data acquisition card PCI-6034E data acquisition,all data storage daemons use database SQL-based storage;measurement module pairs based on different algorithms the measurement procedures were designed separately,including FFT algorithm,instantaneous reactive power algorithm,wavelet transform algorithm and TLS-ESPRITS algorithm.The harmonic pollution source with the characteristics of electric iron harmonics is set up,and the harmonic measurement management system of the design is simulated and tested.The test results show that the harmonic measurement based on different algorithms has subtle differences in the results of harmonic detection.The FFT algorithm can not detect the non-periodic harmonics well;the instantaneous reactive power algorithm can capture very small harmonics work current;wavelet transform can perform local time-frequency analysis and use time domain and frequency domain to jointly represent signals;TLS-ESPRITS algorithm can accurately identify power signals containing harmonics through parameter extraction and decomposition.