Research Of Main Protection Configuration Scheme For Internal Short Circuit Of Large Generators

With the rapid development of economy, the electric power construction in ourcountry has been in a new high-tide. Whether it is hydro-generator orturbine-generator, they all developed towards large and ultra-large. In recentyears, the installed capacity of generators and the annual electric energy productionhas been in sustained growth. Internal short circuit is one of typical faults of largegenerator, and it may generate a short circuit current with great harm. This will causehuge economic damage to the power system and people’s life directly or indirectly.So configure suitable main protection scheme for internal short circuit of largegenerators is very necessary. In this dissertation, the design method of mainprotection configuration scheme for internal short circuit was proposed. The workperformance of four main protections was compared and analyzed and this study ison SF600-42/1308hydro-generator.This dissertation provides the theoretical basisfor high-performance main protection configuration scheme of large generators.First of all, the types of internal short circuit were comprehensive counted inthis paper.The work performance and the constitution forms of four main protectionsinclude zero-sequence current transverse differential protection、 split phasetransverse differential protection(included completely and incompletely split phase)、incompletely and completely longitudinal differential protection were researched. Andon this basis, the calculation method of four main protections sensitivity weresummarized in detail through the setting calculation of differential current andoperating current discussed deeply. This chapter ensures the accuracy of the differentmain protection sensitivity.Secondly, the ways of the stator winding branches combination and its influenceon main protection effect were discussed in two different conditions—two neutralpoints and three neutral points in this paper. Then the sensitivity of four main protections was calculated with the maximum simulation current of transient undergrid-tied and no-load condition. And on this basis, the work performance of fourmain protections was discussed deeply. The laws of sensitivity according to theanalysis results of inter-turn short circuit and interphase short circuit weresummarized. In order to make convenient for power designers to select the mainprotection configuration scheme for internal short circuit.Then the design steps and the method for determining of the final scheme werefurther proposed on the basis of deeply discussing about the work performance offour main protections in this dissertation. Then this study is on SF600-42/1308hydro-generator and combined the method of main protection configuration schemewith the actual short circuit of the generator.The feasible schemes were comparedand analyzed and the final main protection configuration scheme was decided. Themethod of selecting TA model for protections was introduced.At last, based on MATLAB and VB platform development situation, the mainprotection analysis software was developed, the software workflow of the mainprotection configuration for generators was analyzed. The analysis software designmethod of the main protection of internal short circuit for large generators wasdiscussed deeply.This dissertation provides a basis for the research of related topicsin the future.