Generation of tracking and electrical treeing from a void cavity

Abstract

High voltage systems are ubiquitous in the modern world and have become a crucial component of all electricity and power networks. In the UK, renewable energy sources are increasing in volume and are expected to provide most of the generation in the UK of electricity by 2030. High voltage cables will be responsible for transmitting the electricity generated from these sources. Solid insulation plays a vital role in high voltage structures, and any defects or impurities within it can result in failures through the formation of electrical treeing and tracking. Electrical trees are gaseous channels formed in solid dielectrics under high and divergent electrical stress. It is one important mechanism of cable failure. This thesis aims to experimentally explore the process by which tracking and treeing are developed at the interfaces of two polymeric materials in high voltage cables without the implementation of needles in the laboratory. Until now some form of electrode arrangement has had to be used, developing very high divergent fields which are not representative of conditions seen in commercial insulation sytems. The study will focus on electrical tree formation from a void cavity in AC conditions. Additionally, a theoretical model for PD is established to elucidate the stages involved in the creation of tracking and tree structures from the void cavity. The representation of a void geometry and the process by which trees are generated at the interface of polymeric materials enhances the understanding of defects and imperfections that contribute to the occurrence of trees and breakdown in high voltage systems in real-world scenarios. Uniquely in this thesis, an experimental process by which trees can develop in HV systems, without the recourse to the use of needles to enhance the field has been established. This provides the opportunity to study further why electrical trees develop in commercial HV equipment.

Date of Award	1 Aug 2024
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Simon Rowland (Supervisor) & Tony Chen (Supervisor)