| The protective schemes of traction electric system should be reasonable, normal and accurate, which should satisfy the requirements of quick-break, reliability, selectivity, and sensitivity. Recently, the separate element protection mostly is used in traction substation, in some cases which is to against the rapid identification and removal of faults, it even deteriorates operating conditions.Integrated protection can obtain numerous information of substation at the same time, which could not only integrate traditional protection principles but also generate new protection functions to improve the overall performance of protection. Based on reality of traction substation, this paper has summarized features and advantage of integrated protection and performed some works as below:(1) The integrated protection scheme of traction substation is proposed. Firstly the protective schemes of traction substation are analyzed in this paper. With the theory of layered and distributed substation automation system, the traction substation could be partitioned into several bays. Then the integrated protection scheme of traction substation is designed by drawing lessons from integrated protection principles of power system. An integrated protection criterion of low-voltage bus is proposed which could identify bus fault rapidly. It also has practical meanings because of its simple arithmetic, easy achievement and high reliability. At the same time, it is discussed that Integrated protection could also face against wrong-phase coupling of traction feeders exactly, combining correlation analysis of fault component.(2) The integrated backup protection unit of traction substation is devised based on functions. It could complete protection functions by using information from different bays when one bay's protection becomes invalid. It has obvious advantage than separate element protection which not only lowered action time but also avoided extending power failure range. The theory is verified by Software PSCAD/EMTDC simulation.(3) The reliability of integrated protection using in traction substation is also preliminarily discussed. Except ensuring the accuracy of integrated protection theory, the reliability lead-in an economic indicators is also analyzed in this paper. Then it is certified by calculating and comparing that integrated protection has higher level of reliability than separate element protection. Finally, the shortcomings of integrated protection are mentioned. Even so, integrated protection could also play important roles in traction electric system through studying and improving. |
