Study Of Fault Location Algorithms For High Voltage Transmission Lines

As the lifeline in the power system, transmission line takes up important tasks ofconnecting the electrical equipments as well as transporting the electric power. The rapiddevelopment of the electric power industry has increasingly poses higher demand on thesafety, reliability and economical efficiency of the transmission line. Rapid and accuratefault location becomes more and more important.First of all, this thesis firstly briefly introduced the background, purpose and thesignificance of this topic research, then analyzed and summarized the basic approach tothe fault location of the transmission line at home and abroad as well as the currentsituation.Then, in the major of this paper, three methods of fault location have been introduced:impedance method, travelling wave method and natural frequency method.In the part of the impedance method, aimed at defect of the existing power frequencyand impedance needs some given technical parameters of the transmission line, while thegiven parameters are susceptible to environment, this thesis come up with an alternativefault location algorithm without needing given parameters of the transmission line. Itderives the fault location equation from the relationship between the voltages and currentsof positive sequence and negative sequence networks when fault happened. Only bymeans of the GPS synchronization to acquire the voltages and currents datas at both endsof the transmission line, and do some related processing about these datas, then with thehelp of the location equation, we can get the accurate fault distance very easily. This thesisdeduced in detail the formula of the locating algorithm, then conducted a host ofsimulation tests with Matlab/Simulink according to different voltage classes, and theresults proved the correctness of the algorithm.In the part of the travelling wave method, aimed at the defect of the characteristic ofthe malfunction of travelling wave in transient state and the existing method of catchinginceptive travelling wave, this thesis proposed applying Hilbert-Huang translation todetecting the frequency discontinuity point of travelling wave so as to pick up theinceptive travelling wave and achieve fault location. Meanwhile, this thesis made a roughintroduction on algorithm of Hilbert-Huang transform and the method to catching theinceptive travelling wave, and conducted a lot of simulation test on the algorithm.In the part of the natural frequency method, it deduced in details the fundamental principles and methods of fault locating using natural frequency, then introduced how topick to the natural frequency and pointed out the drawbacks of using the conventionalFFT method to do so, and finally proposed, to achieve fault location, applying modalparameter identification algorithm such as Prony Algorithm, ARMA Algorithm, MPalgorithm, and STD Algorithm to picking up the natural frequency. This thesis hasrespectively introduced the mentioned algorithms in detail, built models with acombination of using PSCAD\EMTDC and Matlab software, conducted lots of simulationtest on them with transmission lines of different voltage classes and different lengths.Lastly, a systematic summary on all the research findings in this thesis is introduced. Asystem comparison and summary of the advantages and disadvantages of the threelocation algorithms is given in this thesis.