UK Power Networks experiences faults on Low Voltage (LV) and High Voltage (HV; Note 6.6 or 11kV) underground cables each year, with over 80% of these faults attributed to “age and wear” or “unknown” causes.
A review of soil characteristics in combination with rainfall is likely to provide additional detail to be able to develop an operational faults forecast model. The data on soil characteristics can also be used to develop a soil resistivity assessment tool, for secondary substation earthing studies.
The objectives of this project include:
This project will involve a study of the effect of soil characteristics in combination with rainfall, on a number of LV and HV underground cable faults. The learning from this study will be used to develop an operational faults forecast model for LV and HV underground cables if a well-defined relationship is observed. The project will also involve the development of a soil resistivity assessment tool, for secondary substation earthing studies, using information on soil characteristics.
Traditionally, forecasts of underground cable faults are based on outputs from network monitoring devices and operational experience. However no standard approach exists to quantify the potential impact of rainfall and soil type on underground cables and faults. Similarly, earthing assessments at substations are typically done by taking soil resistivity measurements on site followed by desktop calculations. This project provides and innovative approach to fault prediction for underground cable faults by seeking to quantify the relationship between soil characteristics (in areas with underground cable) and the amount of rainfall. It also seeks to use the soil characteristics to build a soil resistivity model which would be used in an earthing assessment tool. We believe that this has not been tried before because the data on soil types has not always been available to the degree of accuracy that it is today.
The project will improve our understanding of the relationship between soil types, rainfall and underground cable faults.