Research On Negative Sequence Compensation And Harmonic Suppression Technology For High-speed Railway Supply System

As a special kind of electric load, electric locomotives in high-speed railway cause serious power quality problems, such as negative sequence and harmonic currents,which not only damage electric devices and bring additional power energy lost.Seriously, they will cause electric accident.These power quality problems threat the traction power system and the upon power system.Therefore,an effective power quality improvement method for eliminating negative sequence and harmonic,is needed to study to enhance the stability and safety of traction power system.This paper studied topology selection of high-speed railway negative sequence and harmonic integrated compensation system,detection and control method for negative sequence and harmonic,parameters design of compensation system.And a prototype and its digital control system were designed in the laboratory to verify the results for theory. The work in this paper will provide theoretical principle and engineering design reference for high-speed railway negative sequence and harmonic integrated compensation technology.Compensation performance is determined by the topology of negative sequence and harmonic integrated compensator. Based on analyzing the topology of various compensation devices at home and abroad,this paper made a deep research on two topology which have large advantage in compensation, that is, the railway static power regulator(RPC)and the combined system of injection type hybrid active power filter and static var compensator(IHAPF+SVC).This paper analyzed their structural characteristics,established the mathematical model and made a deep research on their compensation characteristics and performance separately. Simulation models were also established,and the simulation results of the two topology compensating negative and harmonic were given.By comparison study, this paper choosed the RPC as high-speed railway integrated compensator topology.Then,the negative sequence and harmonic compensation reference current detection technique of RPC was given in this paper, when the traction power supply system uses three phase V/v traction transformer. Base on the single-phase harmonic and reactive detection methods,this paper proposed negative sequence and harmonic compensation reference current real-time detection method for RPC.Meanwhile,the control method for RPC is studied in this paper. To maintain the voltage stability of railway power regulator's DC side,closed-loop control was adopted.The output of DC side voltage controller is converted to AC active power current,which was added to the negative sequence and harmonic compensation reference current to get the output reference current instruction for two inverters in RPC.Hysteresis control method was used in the current track of two inverters to realize the voltage stability control of DC side and the compensation current track of negative sequence and harmonic.In order to make the railway power regulator have better performance, component parameters selection method was studied.Such as step-down transformer ratio and capacity design, AC side inductance parameter design and DC side capacitor design are given in this paper. The design of RPC experimental device especially the design of digital control system based on DSP28335 including hardware and software design was also given.The experiments were conducted using the prototype,and the experimental results verifies the effectiveness of the proposed detection and control methods for RPC.