Study On Single-phase Hybrid Harmonic And Reactive Compensation System

With the rapid development of electrified railway, the electric railway traction load has been constantly growing. Due to its own characteristics, the electric railway traction power supply system causes a certain amount of pollution on the power system, which has seriously affected the quality of power supply. Therefore, the research on harmonic and reactive compensation for electric railway traction load is of great significance.The basic principles and evolution process of Active Power Filter (APF) are first introduced. The scheme and structure of single-phase hybrid filter system is then illustrated and quantitative analysis is made based on the harmonic and reactive compensation principles. Through theoretical derivation, the said system has been proved to have the function of harmonic and reactive compensation.By analyzing and comparing a couple of harmonic and reactive current detecting methods and focusing on the active power current separation detecting method and instantaneous reactive power theory, a reactive current detecting method of single-phase system based on the instantaneous reactive power theory is proposed, which will improves the speed and accuracy of reactive current detecting.The control strategy of active power filter is analyzed. The optimized set sideband control method and other two methods based on unipolar PWM control and the triangular wave PWM are mainly studied. According to the practical requirements of the project, an improved triangular wave PWM control method is proposed which allows the high power reactive compensating devices work under the condition of fixed frequency and improves the accuracy of current tracking.By analyzing the general requirements for design of system parameter, a main circuits parameter designing method of active power system is proposed, and the parameter of single-phase hybrid filter system is obtained.A traction power supply system simulation model including single-phase hybrid filter system is established in the PSCAD/EMTDC environment to verify the compensation effect of the system. The simulation results confirmed the correctness and feasibility of the overall structure of the system, the method of current detection, control strategies and parameters calculation.