Transmission lines protection techniques based on wavelet transform

Development of different modules of a transmission line digital relaying system is outlined in this thesis. Different modules such as fault detection, phasor estimation, phase selection and fault location are designed, implemented and tested. The developed distance-relaying algorithm is suitable for protecting single circuit transmission lines and is employed in conjunction with current differential protection to protect double-circuit transmission lines.; A new distance relaying algorithm based on Wavelet Transform (WT) is developed. The measured three current and three voltage signals at the relay location are digitized and decomposed into different frequency bands using WT. A fault can be detected from the highest frequency band of the current signals and the phase(s) on fault can be identified. All voltage and current fundamental frequency phasors can be estimated from the frequency band that contains the fundamental frequency accurately and the impedance to the fault can be calculated.; Simulation studies have been performed on a typical power system model using PSCAD program. The proposed algorithm is examined under different operating conditions including internal, high resistive and external faults. Further studies have been performed to examine the performance of the algorithm during line charging. The results obtained indicate that the proposed algorithm has the ability to rapidly detect faults and correctly classify all types of internal faults within one cycle of the fundamental frequency.; The WT distance-relaying algorithm has been implemented on a Digital Signal Processor (DSP) board. Using a physical model of a transmission line with a micro-alternator connected at one end and a large system at the other end, extensive experimental studies have been conducted and the performance of the proposed WT distance-relaying algorithm is verified.; The developed WT distance-relaying technique is combined with the current differential technique to protect parallel transmission lines. The new algorithm is proposed to overcome the problems that result from the sole use of either of these two techniques. (Abstract shortened by UMI.)...