Dionisios Pylarinos

Impact of noise related waveforms on long term field leakage current measurements

Leakage current (LC) monitoring is widely employed in order to investigate electrical surface activity on high voltage (HV) insulators. Long term field monitoring is required in order to obtain an actual view of the phenomena. Therefore any monitoring system is bound to encounter data size problems. A number of solutions have been proposed to address this problem by extracting different values from the measured waveforms as a performance indication. However, a parameter that is fully representative of the waveform is yet to be determined. Hence, measuring and storing of the actual LC waveform is still required on sites for research and monitoring purposes. In addition, field related noise can result to misinterpretation of the actual activity. In this paper, a number of 26089 waveforms, recorded in a 150 kV Substation on four different post insulators that are part of the grid, are investigated. The monitoring period exceeded six years. Different techniques are applied and evaluated on the data set, employing simple numeric criteria and more advanced techniques such as Fourier and Wavelet analysis. Results are presented towards addressing the problems of noise and data size. The study objective is the incorporation of the results in improved leakage current monitoring systems.

A Hybrid Support Vector Fuzzy Inference System for the Classification of Leakage Current Waveforms Portraying Discharges

Abstract Several techniques have been applied on leakage current waveforms in order to extract information regarding electrical activity on high-voltage insulators. However, a fully representative value is yet to be defined. In this article, a hybrid support vector fuzzy inference system is introduced as a classification tool. The system incorporates fuzzy logic, genetic algorithms, and support vector machines. Apart from the classification accuracy achieved, the system also produces a set of fuzzy rules under which the classification is made, allowing a further insight of the process. A comparison is made to other classification tools previously applied on the same data set.

Comparative investigation of silicone rubber composite and room temperature vulcanized coated glass insulators installed in coastal overhead transmission lines

The fault-free performance of outdoor insulators is a matter of great importance for power utilities as a single insulator fault may lead to an extended outage. Several factors related to operation conditions affect the performance of outdoor insulators, with pollution being probably the most significant one [1]-[3]. Coastal areas are considered heavily polluted due to the deposition of sea salt on the insulators. When the deposited salt is diluted in water through humidity, drizzle, fog, or light rain, a conductive solution is created and leakage current flows on the surface. The activity may advance, under favorable conditions, to flashover. Therefore, the local weather and climate is an important factor for the determination of pollution severity as strong winds carry more salt and frequent rains may provide natural cleaning.

A Novel Autonomous Monitoring System for Distributed Leakage Current Measurements on Outdoor High Voltage Insulators

 Abstract The reliable operation of power networks is strongly related to the performance of high voltage insulators. Local weather conditions, environmental pollution, insulator material and high voltage level mainly affect the operation of the installed insulators in high voltage transmission systems. At the last decades, important advance has been made in high voltage insulation by introducing composite materials with innovating advantages comparing to the traditional ceramics, improving the insulators performance even heavy polluted conditions. However, composite materials have limited operation life respecting to their exposure to field ageing mechanisms. Considering all these parameters, the common maintenance techniques of high voltage insulators cannot confront the problem. A parameter which can substantially contribute to the maintenance actions of power utilities is the monitoring of the electrical surface activity of insulators. In this framework, a novel low cost autonomous leakage current monitoring system for high voltage insulators is proposed and gradually constructed in order to respond to the advanced needs of power operators.