Distributed Fault Location Method For Branch And Hybrid Transmission Lines

The electricity demand is constantly expanding because of the increasinglygrowing national economy. With the size of power system getting larger and larger,the line type has already changed. There are more and more branch lines and hybridlines, which can make the city more beautiful and neat. But for transmission line faultlocation, it’s a great challenge. Once fault occurs on branch lines or hybrid lines, itmay result in greater losses compared to traditional lines, which means much moreimportance of fault location.At first, this article expounds the process of transmission line traveling wave. Thetraveling wave de-noising principle and modulus maxima principle of the waveletanalysis is described in detail, and the wave extraction is studied. Based on thesetheories, the real-time operating status of the transmission lines on traveling wavevelocity is analyzed specifically. The essential influence of the traveling wavevelocity is found, that is the environment temperature and humidity, the conductortemperature and the atmospheric pressure. To ensure the accuracy of fault location,the real-time wave velocity need to be detected or calculated online.The article proposes appropriate fault location methods for branch lines andhybrid lines. The fault branch or fault section is distinguished according to the faulttraveling wave energy or polarity. The location of the fault can be calculatedaccording to the first two waves detected by the fault current detections near the fault.This method can calculate the real-time velocity online, and reduce thesynchronization error caused by GPS. It is also free of the fault type, fault locationand fault resistance effects. The accuracy of the method is less than100m which isverified by simulation of PSCAD.According to all the above theories, the transmission line distributed fault locationsystem is developed and its system components and the working principle is describedin the article. Using the Rogowski coil as a sensor with no hysteresis effect can uploadthe fault information to the monitoring master station via the remote wireless networkwithout distortion. The monitoring master station can realize precise positioningaccording to the special algorithms made for transmission lines.