Application of thermal network modelling for MV GIS design optimization

This paper presents implementation of thermal network (TN) approach for thermal management and design optimization of medium voltage gas-insulated switchgears. It covers solution based on thermal network coupled with pressure network which allows to simulate mass flow phenomena within enclosed tank with more detailed temperature distribution. The approach is a methodology previously developed by ABB in collaboration with Technical University in München and allows for solving network-type thermal models with bidirectional fluid flows. Coupling between networks representing thermal and mass flow phenomena is done at pre-defined library component level which, combined with sufficient accuracy, makes a very good engineering tool allowing for precise numerical calculations without the need of solving complex thermodynamic problems for every analysed case. The focus of this study is to present the benefit of using such approach to simulate thermal performance of entire switching device and find components which require improvements. As a case study, results of continuous current test of a SF6-free switchgear are being presented highlighting accuracy of temperature distribution up to +/-3K for a properly tuned model.