Fault Detection and Localization of the Underground Cable based Distribution System using Tunnel Magneto-Resistive Sensors /

Abstract

Signal processing technique is a fast growing technique which provides energy overview of the signal through which a lot of protection issues can be handled. Furthermore, signal processors are mostly used in the protection equipment. Similarly, many techniques have been previously used for protection purposes, among which Hilbert Transform (HT) is one of the most effective methods. Hilbert Transform (HT) has been used for many technical applications like, overhead lines, smart grid systems and induction motors. It provides real time monitoring of the system and quick response to the fault triggered. Therefore, HT is a preferred technique being incorporated in this system. In this research, Hilbert transform is used as a signal processing technique for the protection of the underground power line system with non-intrusive TMR sensors, Hilbert transform technique is used with the filter to extract the faulty signal; filter will provide narrowband signal, which is further processed through HT in which complex signal is achieved. Using complex signal, we are able to find the magnitude with this envelop signal, signal conditioning is being carried out in order to provide binary signal for protection actuation. In the process of signal conditioning, two similar signals difference is calculated (one HT signal at “time t” and other one at time “t-1”) and as a result maximum values are achieved and are compared to the threshold already defined in the system. After detection, Hilbert filter transform is used with the same envelop signal for energy calculation. The energy calculation provides us polarity signals between two bus bars on the two end of the underground distribution line. After that, the energy spectrum signal root mean square and the ratio is calculated for actuation. Now, this ratio is analysed with the thresholds given and when the polarity is different between two ends, it localizes the faulty line. To be precise, Hilbert transform technique magnitude is implemented for the fault detection and Hilbert transform energy spectrum polarity is analysed for the localization of the fault. Moreover, fault detection and localization measurement is performed through Tunnel Magneto Resistive (TMR) sensor on the underground line. This TMR sensor detects the movement of the electrical flow in the lines through magnetic field. Furthermore, different cases and scenarios are developed based on distribution generation connection to the grid. Hence, cases are divided in such a way that fault detection with DGs are either intact or not. For this, MATLAB SIMULINK software is used and this scheme has shown promising resultsfor fault detection and localization with reliable outcomes. After a comprehensiveanalysis, the results indicate that the proposed method is 98% reliable as well as moreefficient for the protection of underground power distribution lines. This schemeprovides better impulse response during the start of the fault and step responsethroughout the fault existence which can be easily detected hence almost zero falsealarms or miss operations as well as safety of the equipment is ensured. This techniqueis less costly due to the TMR sensor.