Current Traveling Wave Based On Wavelet Analysis, Double-ended Ranging

As the development of electrical network, there are more and more HV transmission lines. HV transmission lines are significant components of electrical system. They take on the task of transmitting electrical energy. However most faults of electrical system are associated with them. Fault locators of high speed and high accuracy are helpful can help to ensure the safe operation of electrical system, which have enormous economic benefit as well as social benefit. Thus, research on fault location is significant and important.In this thesis some existing methods of transmission line fault location are summarized at first, those methods' primary merits and disadvantages are analyzed as well and the basic theory of wavelet transform are introduced. Based upon Multi-resolution analysis theoretic, traveling waves mixed noise signal are implemented by wavelet transform. Based upon change rule of the modulus maximum value of traveling wave signal, a new de-noise algorithm and a double-terminal location method based on wavelet transform without using down-sampling by two are gained. Influence of fault type, fault resistance, line length and fault inception angle on fault location result using current traveling wave has been studied by using EMTP.The key of fault location using traveling wave is to exactly find the arrive time of traveling wave. This paper discusses the fault location error caused by down-sampling by two in the wavelet transform algorithm, theory analyses and the emulation result by EMTP indicate that the precision of distance measurement of traveling wave can be improved without using down-sampling by two. This paper also explains why the modulus maximum value of traveling wave signal decreases with the increasing of the scale, and gives a new method optimizing both beginningand end data. For the purpose of accurate location using traveling wave, this thesis has studied the change rule of traveling wave and modulus maximum value of wavelet transform which affected by fault resistance, line length and fault inception angle.Based on the theory discussed forward, this thesis design fault location software using the excellent tool C++ Builder. The software can find the arrived time of the first traveling wave automatically, and arrive at the purpose of automation measuring distance. The software is efficient with a good man-machine interface, flexible and easy to extend.