Using online partial discharge measurements to optimise asset management of medium voltage cable terminations
Abstract
Medium voltage cable terminations are critical components within the electricity network and are expected to have high reliability to ensure network performance and compliance to regulatory requirements. It is evident that failure rates are currently alarmingly high and indicates that more than 20% of some cable system failure relates to cable terminations. It appears that poor workmanship is the main contributing factor.
The termination product itself is of high quality with well-established manufacturing methods and processes. The electricity industry is also well recognized with a vast number of different testing standards and methods for cable systems. Although good testing standards are by no means a guarantee that good workmanship was executed on site, it is a valuable method to verify the quality of the workmanship. This dissertation focuses on using online partial discharge measurements to optimize asset management of medium voltage cable terminations.
Cable terminations as an asset portfolio within asset management is discussed with reference to international asset management standard. The importance of quality assurance is addressed by identifying current shortcomings and concerns.
The dissertation is supported by making use of three methods. Termination modeling and simulation are done with a Python program by implementing the 3-capacitor model. Finite element analysis is done with QuickField software program. Actual partial discharge measurement data was obtained by conducting an accelerated aging experiment by creating five artificial termination defects. The last method gathered data from role-players within the industry by means of an online survey in the form of a questionnaire.
The dissertation converges into the optimization of asset management for cable terminations by addressing suitable structures with the overall objective of quality assurance and reliable operations. A recommendation is made by formulating two new test methods for cable terminations by using unconventional partial discharge measurements.
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