Fault Analysis Of 6-phase Transmission System

Six-phase transmission belongs to multiphase transmission. It can evidently improve power transmission density and easily work with 3-phase system.It also can lower phase to phase voltage ,and has lower requirement of the capability of the high voltage-breaker's port.Moreover , six-phase transmission can utilize the overhead transmission right-of-way efficiently,it just need light transimission tower. So it is adptable for our country in the high voltage transmission system.The research on the fault of the Six-phase transmission system can provide data-base for its relay protection. so it is of great importantance and has large practical value.Six-phase transmission system has 120 kinds of fault, so the research of its fault should be more complicate than 3-pahse transmission system. This article introduce the method which inducts the same positive sequence,the same negative sequence,the same zero sequence,the opposite positive sequence, the opposite negative sequence, the opposite zero sequence six sequence variable.The method is introduced for the first time in Six-phase transmission system.The article use this method analyse the fault of the system.It classify the 120 kind of faults to 13 categories,and draw the sequence system net for each sequence variable. It uses the frontier condition to draw the composite sequence system net ,and then find out the characteristic of each sequence variable when fault happens.In this article,the method used for research of the fault just need one step to switch the phase variable to the sequence variable.It doesn't have to dismiss,and has shorter data window and sooner calculation speed.This article use MATLAB emluate the faults of the system,the results prove the analyse of the faults.In the end of the article,a criterion for distinguishing faults is put forward.