Research On Hybrid Active Power Filter Of Traction Substations And Its Controller

In our country single_phase rectifier drives most electric locomotives, which produce many harmonic currents. Nowadays , in our country most traction substations use 3 orders single tuned passive filters to suppress harmonics, the performance of this way is far from satisfied. So it is necessary for us to take new steps to suppress harmonics well. Active power filter can overcome the shortcomings of passive power filter and suppress harmonics caused by electric locomotives well, but the cost of active power filter is very high .Using hybrid power filter consisting of passive power filter and active power filter can avoid the shortcomings of passive power filters and active power filter but retain their advantages. So it is an ideal scheme for us to suppress harmonics of electrified railway.The main work of this dissertation is based on the research result of "Comprehensive research on harmonic suppression and adjustable compensation for reactive power in traction substations" project which is supported by science and technology department of railway ministry. This dissertation discusses a type of hybrid power filter that is connected in parallel with the bar to suppress harmonics of electrified railway. This dissertation try to design hardware and software of the hybrid power filter in detail considering factors including investment, security and filtering performance.This dissertation discusses best installing position of the hybrid power filter and the scheme for the hybrid power filter to work with an adjustable reactive power compensation device .The style of invertor and control method of PWM are discussed in this dissertation.The mathematical model and arithmetic of optimization design on least investment of the hybrid power filter are given in this dissertation. By using detecting data from a certain traction substation this dissertation designs hybrid power filters for it. The dissertation discusses designing rule of output filters of APF, write optimization program to design the output filters and give the result of the design.Control system is designed for the hybrid power filter. The control system is composed of controller for forming output voltage command and controller forfollowing command. Active power filter needs a link for following command with strict phase characteristic, so the design of controller for following command is very important. Nowadays research about active power filter is mainly focused on controller for forming output voltage command and little on controller for following command. Design of controller for following command is discussed in detail.To prove the result of theoretical analysis and design a simulation model for a certain traction substation is established under the MATLAB /Simulink flat. The simulation results show that the proposed hybrid filter gives satisfactory performance and the control system is robust and has good tracking characteristic.