Power Quality Analysis Of High-speed Rail Traction Power Supply System

With the rapid development of technology and economy in recent years, railway transportation, as the main transportation, has a qualitative leap. That is from the earliest gas scooter to the common electrified railway to high-speed rail with the speed of more than 350 km/h.The characteristics of high speed and high density of high-speed railway have brought substantial convenience to families. But at the same time, the locomotive load power, serious imbalance and power quality problem of traction power supply system have become more serious.In today’s power in all walks of life, research on power system causing power quality problem is urgent, especially because the power equipment is more precise and sensitive.Power quality problems of high speed railway mainly reflect on the harmonic, negative sequence and voltage fluctuation. Based on system parameters of Mingyue line Yueliang Wan traction of Xinyang Mingyang converting station and power quality test results used by PS- 8 power quality tester, the high speed railway traction power supply system and CRH high-speed emu load are analyzed in theory and simulated.Scientific computing simulation software MATLAB is used as the simulation software, which is accepted internationally. In this thesis, connection type and power supply way of the existing high-speed railway traction transformer are analyzed and compared in detail, and the power supply system simulation model of V/X wiring, the AT power supply mode consistent with Yueliang Wan traction is established, and a large number of simulation data is used to verify the reliability of the model.In this thesis, the causes of negative sequence current of high-speed railway are analyzed in detail. The harm of negative sequence current is introduced.And various measures compensating imbalance are introduced and compared and the RPC synergy MSVC compensation scheme is further studied.This thesis illustrates instantaneous impact and harm when the high-speed locomotive entering power supply area. By setting the circuit breaker opening and closing time, impact process is simulated. The simulation results and the actual data are analyzed and improvement measures of voltage sag are introduced. In this thesis, causing reason and the influence of harmonic are researched from two aspects of locomotive harmonic and web side harmonic, and the composition and effect of harmonic suppression device are analyzed briefly.It is concluded that the three-phase imbalance degree is higher than that of ordinary high-speed railway electrification railway, and the problem of negative sequence current is serious. New compensation device is needed to furnish so as to tackle the problem. Moreover, the appearance of impact current and voltage sag is frequent, which has great impact on sensitive users. Harmonic governance of high speed railway is ideal, especially the content of low-order harmonic is extremely low.