Design analysis of short neutral section through dynamic modelling of performance

Abstract

UK railway overhead line electrification employs a feature known as ‘short’ neutral section which uses insulators spliced into the contact wire to separate the electrical phases, and they are known as a cause of reliability problems. This research proposes to develop, validate and apply a hitherto unexplored approach to studying short neutral section behaviour. This research briefly initially examines the experience of British Rail with the introduction of the ceramic bead neutral section and its development during the 80s and 90s, and the subsequent introduction and development of a further proprietary type in the early 2000s, which is then assessed in detail. Using information from Network Rail, the significant failures of the main types of neutral sections are examined over a 10 year period for which adequate data exists. European practice is briefly examined. Current methods for analysing the interaction of pantograph and overhead lines are investigated, and the principles are adopted into a bespoke methodology implemented using proprietary software Ansys, rather than custom code as is current widespread practice. This methodology is constructed using finite element and multi-body principles and is successfully validated against ‘benchmarks’, in accordance with current European practice and standards. Mathematical models of a neutral section are constructed using their physical characteristics and data captured in lab tests, and the behaviour against real UK pantographs is simulated using this method. Findings are again successfully validated against real line test data. Using the result, the sensitivity of the neutral section performance to particular parameters of its construction is tested, allowing opportunities for optimisation to be identified, and improvements proposed, successfully demonstrating a (previously untried) validated methodology for examining the neutral section problem. This work has answered all its research questions.