Power Quality Disturbances and Protective Relays on Transmission Lines

Power quality concerns the effect of voltage disturbances on end-user equipment and of current disturbances on network components. Power system protection concerns the detection of faults in the system from measured voltages and currents. However, non-fault voltage and current disturbances may lead to the inadvertent detection of a fault in the same way as voltage disturbances may lead to the tripping of end-user equipment. Starting from the principles (algorithms) of the relays, a quantification approach is developed to assess the isturbance impact on the relays. The quantification is based on the relay response after processing the disturbance signals by relay filters. This makes it possible to quantify the disturbance impact by the consequences caused by the disturbances, other than by the signal waveforms of the disturbances. Power transmission lines protection is one of the most important concerns for power utilities. Different types of faults occur on Transmission Line. From the transient phenomena, faults on transmission lines need to be detected, classified, located accurately, and cleared as fast as possible. Identification and classification of faults on transmission line are essential for relaying decision and auto-reclosing requirements. This dissertation presents a novel Wavelet-Fuzzy combined approach for digital relaying. An algorithm based on wavelet multi-resolution analysis (MRA) is used for classification of transmission faults for quick restoration of power supply and for improving the transient stability