Study On Optimization Design Of Cophase Continuous Traction Power Supply System

With the development of the railway industry in China, increasing speed and loading of trains has been the trend in the recent years. However, in the existing railway system, sub-phase power supply technology is used, i.e., there exists electrical separation in the feeding section, which limits the increase of train speed. In order to overcome the drawback, cophase power supply technology that removes the electrical separation at the substation terminal is developed. It has the functions of filtering harmonics, compensating reactive power and eliminating negative-sequence components, hence improving the power quality of the electrified railway system. In practice, combined cophase power supply technology has considerably reduced the equipment investment, laying a good foundation for the development of the cophase continuous traction power supply system.In the traditional design procedure of traction power supply system, the locations of substations are planned based on the experience of the designer; and the capacities of traction transformers are determined by the load of every arm. But in the design of cophase continuous traction power supply system that has no electrical separation and is continuous through the line, tradition approach cannot be used to calculate the capacities of traction transformers because load consumptions are not furnished by a single substation.In this dissertation, an optimized design scheme of the cophase continuous traction power supply system is studied through the computer simulation techniques and artificial intelligence algorithms. At the beginning, the basic principle of the particle swarm optimization (PSO) algorithm is briefed. The algorithm is modified and applied to solve multi-objective optimization problems; and some testing functions are used to verify its validity. Next, the traction computation and simulation model according to traction computing principles is set up and analyzed; and the simulation results are compared with the measured data. Then, the simulation model of traction power supply system is built to calculate the power flow and contrast the results with those computed by the commercial package of power system simulation in order to confirm the effectiveness of the modified algorithm. At last, the cophase continuous traction power supply system is optimized by the modified PSO algorithm; and comparisons are made with the traditional power supply mode to demonstrate its advantages.In all, this optimized design scheme can be implemented to assist the railway power system design and has good practical value.