The Research And Application Of Voltage Sag Control For Electrified Railway Station

With the development of science and technology,the users' demand for power quality is constantly improving.In various power quality problems,the power supply voltage sag has the most serious impact on power users.In recent years,China's electrified railway and high-speed passenger dedicated line have developed rapidly,and the capacity and quantity of electric locomotives are increasing.During the operation of the locomotive,a series of energy quality problems have been brought to the access point power grid and the related railway stations.Among them,the electrical equipment failure or even damage caused by voltage sags seriously affects the normal operation of railway stations.Therefore,the treatment of voltage sag in electrified railway station has very important engineering application significance.This paper first introduces the power quality problem,and introduces the outstanding voltage sags,and analyzes the causes,hazards and related measures of the voltage sags in detail.A dynamic voltage restorer for voltage sag is introduced,and its research status is analyzed.Through the field test of the power quality of railway station,the specific situation of the voltage sags is analyzed,and the automatic regulator based on the combination of multi tapped autotransformer and passive filter is preliminarily treated.The effectiveness of the set is proved by the actual operation test in the field.Because of the structural characteristics of the device itself,there are still some limitations in its practical application.The single-phase dynamic voltage restorer(DVR)applied to the voltage sag control of railway stations is studied.The working principle and topological structure of singlephase DVR,the detection methods of voltage sag,and the compensation and control strategy of DVR are described in detail.The single-phase voltage sags detection method based on the instantaneous reactive power theory is simulated and analyzed,and the small delay angle improved alpha beta transformation is used to detect the single phase voltage sags,and the detection real-time performance is improved.The hardware part of the single phase DVR is designed,and the topology of the single-phase DVR main circuit is designed,including the energy storage unit,the inverter unit,the connection transformer and the structure of the filter and the selection of the device.DSP+FPGA based control unit,AC and DC sampling circuit and photoelectric isolation circuit are designed.The software part of the single-phase DVR system is designed for the voltage sags detection,phase-locked loop,compensation voltage control and working mode,and the simulation of the DVR system is carried out with the phase-locked method and the compensation voltage control method.The simulation results verify the correctness and feasibility of this design.Based on the design of hardware and software,a prototype of single-phase dynamic voltage restorer for voltage sags in electrified railway station is designed,which lays a foundation for the application of the follow-up engineering field.The research design of this paper has high engineering application value,and provides an economical and practical plan for the treatment of voltage sag in electrified railway station.