Underground Cable Soil Thermal Resistivity Estimation Without Weather Data
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Solution Overview
Problem
Existing methods for determining the thermal resistivity of soil surrounding underground cables are complex and require weather data, which can be difficult to obtain, necessitating a simpler and weather-independent approach.
Innovation Solution
A method and arrangement that utilize temperature sensors on the cable surface and in the soil, combined with current measurements, to estimate thermal resistivity without relying on weather data, employing a thermal model to iteratively refine the estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a weather driven method is used to determine thermal properties of soil, then the thermal resistivity estimation can be obtained, but the method becomes complex and requires weather data that is hard to obtain
Solution Approach 1:
The invention extracts the essential thermal resistivity determination from complex weather-driven methods by using only temperature sensors on and near the cable, eliminating the need for weather data while maintaining estimation accuracy
Solution Approach 2:
The cable itself serves as a temperature sensor mounting structure, and the soil temperature is measured at a distance from the cable where it is uninfluenced by cable operation, allowing the system to determine its own thermal properties without external weather data
2Measurement precision
If a weather driven method is used to determine thermal properties of soil, then the thermal resistivity estimation can be obtained, but weather data is hard to obtain
Solution Approach 1:
The invention removes the dependency on external weather data by extracting thermal resistivity information directly from temperature measurements on the cable and in the surrounding soil, making data acquisition simple and self-contained
Solution Approach 2:
The system uses its own operational data (cable temperature and nearby soil temperature) to determine thermal resistivity, making the system self-sufficient without requiring external weather information
3Reliability
If safety margins are increased for cable operation, then cable safety is improved, but cable efficiency and overload capability are reduced
Solution Approach 1:
The invention implements feedback by continuously monitoring cable temperature and soil temperature to dynamically determine thermal resistivity, allowing the system to adjust operational parameters based on actual thermal conditions and enable safe overload operation
Solution Approach 2:
The system changes operational parameters (current load) based on determined thermal resistivity values, allowing optimization of cable utilization while maintaining safety through real-time thermal condition awareness
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables safe overload operation with low safety margins, efficient cable usage, and allows for implementation with minimal additional sensors, facilitating accurate thermal resistivity estimation.
Implementation Method 1
The estimation of the thermal resistivity of soil may be based on an estimate of the temperature at the exterior surface of the cable caused by power losses in the cable when the measured current is running in the cable
Implementation Method 2
obtaining a second temperature from a second temperature sensor placed in the soil at a distance from the cable
Data Source
AI summary
The invention is concerned with a method, arrangement, computer program and computer program product for estimating the thermal resistivity of soil surrounding an underground cable. The arrangement comprises a thermal resistivity estimating unit that obtains a first temperature (Ts) from a first temperature sensor at an exterior surface of the cable, obtains a second temperature (Ta) from a second temperature sensor placed in the soil at a distance from the cable, obtains a measurement of current (Ic) transmitted in the cable and estimates the thermal resistivity of soil based on the first and the second temperatures (Ts, Ta) as well as on the current measurement (Ic).