Electromagnetic Time Reversal to Locate Partial Discharges
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Abstract
Energy is crucial for the developing world and must be provided when needed to avoid a serious impact on society. Electricity is becoming the increasingly central energy source, strongly demonstrated in the current pandemic, allowing people to remain in contact and to work from home. Electricity security is the power system’s capability to withstand disturbances/ contingencies with an acceptable service disruption and represents a crucial concern for policy decision making at all levels. Usually, service disruption is due to cables’ insulation damage, often caused by partial discharges (PDs) that are localised electrical discharges that partially bridge the insulation between conductors. Since PD is one of the best early-warning indicators of insulation damage, the on-line PD location is the most suitable method to prevent faults, enhancing network reliability. Most location methods are traveling wave-based techniques, using the principle that PD produces electromagnetic waves which are measured at different line points. The difference in the times of their arrival allows the PD localisation. However, their implementation is difficult due to the need for synchronisation and their accuracy is influenced by the PD signals distortion and the presence of electromagnetic interference on networks. This project proposes a new method to locate PDs using the electromagnetic time reversal (EMTR) theory. It is based on the time reversibility of the wave propagation equations and on the spatial correlation property of the EMTR theory that allows refocussing the time-reversed back-propagated PD signals into their original location. The method has been designed in simulation using the Transmission Line Matrix method and experimentally validated on real MV networks. It is able to locate PDs using only one observation point in the harsh electromagnetic environment of real networks with an accuracy of >99%.