New Distance Protection Based On Matlab Analysis

In the modern electrical network, along with the ultrahigh voltage, large capacity, the long-distance electric transmission line increases unceasingly, it proposed high, stricter request to the electrical power system relay protection installment.It is very important to analyze distance relay's action during power system swing under short-circuit. System swing comparatively sees one kind of exceptionally running status in the electrical power system. There are many reasons to causes system swing. The electrical power system swing can cause from the protection moves,how prevented the system swing causes from the protection moves always is by mistake relay protection worker's important topic.This article first summarized the research present situation of the protection's movement condition under system swing under short-circuit condition. For ease of analysis we have established double-end power source model, first used the fault analysis the knowledge to carry on the analysis regarding this model under each kind of short circuit breakdown situation to calculate, using computation result, compiles short circuit computation analysis software with MATLAB. This software has the formidable computation function and cartography function, In order to use convenience,it has also designed user interface. Using this software, we may calculate accurately when power system swing under short-circuit protects the installment place three-phase voltage and magnitude of current, draws up vector diagram, we also may draw the survey impedance along with the system both sides electric potential included angle or transition resistance variable change trajectory diagram.Finally this article uses the compilation the MATLAB software union theory to prove, This paper analyzes a new criterion to ground distance relay's action during power system swing under single-phase grounding fault. This ground distance relay movement criterion is the busbar voltage, backing voltage, the zero foreword electric current and the negative sequence electric current four quantity phase relations which obtains after the comparison breakdown by determines the relay movement behavior situation.The study shows the relay can measure the point of the fault correctly during power swing. Its performance is not affected by fault resistance, and it has good phase selection and distinct directionality. We also discovered in the analysis that: this has the strong anti-transition resistance ability from the relay, and when the transition resistance is big, its movement performance is more superior. Simultaneously analyzes the process to indicate that: Compares with the pure use analysis law , Using this short circuit analysis software to be possible to cause the analysis process big simplification, causes the analysis to be more comprehensive, it is easy to discover the regularity in the analysis process, and the conclusion is more clear. Therefore this software development has the great practical value.