Heat Monitoring of Photovoltaic DC Arcing Cable Based on Non-Contact Temperature Measurement Technology

Introduction

In photovoltaic (PV) power stations, DC arcing cables are critical for energy transmission. However, harsh operating environments and overloading conditions often lead to cable overheating, posing significant safety risks. This study proposes a non-contact infrared temperature measurement method to monitor the heating of DC arcing cables, which effectively detects potential overheating issues and prevents system failures.

1. The Need for Non-Contact Temperature Monitoring

Traditional methods, such as gas sensor arrays and surface temperature sensors, have limitations:

• Gas sensors are sensitive to environmental changes, leading to inaccurate results.
• Surface temperature sensors are affected by installation location and can produce false readings.

The non-contact infrared temperature measurement technology overcomes these issues by directly capturing the thermal radiation of cables, allowing real-time monitoring without physical contact.

2. Working Principle of Non-Contact Infrared Measurement

The method relies on the Stefan-Boltzmann Law, which relates the radiation intensity to the surface temperature:

Q = σ × δ × (T₁ - T₂)

where:

• Q = Radiation intensity
• σ = Stefan-Boltzmann constant
• δ = Cable surface emissivity
• T₁ = Cable surface temperature
• T₂ = Ambient temperature

3. Infrared Image Acquisition and Preprocessing

The system uses a matrix-type infrared temperature measuring device to capture thermal images and detect abnormal heat spots caused by cable overheating or poor connections. Advanced image denoising techniques like Gaussian filtering and histogram equalization are applied to enhance accuracy.

4. Heat Monitoring Through Relative Temperature Difference Method

The relative temperature difference method is applied to detect overheating areas:

γ = [(T₃ - T₄) - (T₅ - T₄)] / (T₃ - T₄) × 100%

where:

• T₃ = Temperature of the target point during heating
• T₄ = Normal temperature of the target point
• T₅ = Ambient temperature

5. Heat Monitoring Results and Comparison

6. Conclusion

•  The non-contact infrared temperature measurement method can accurately detect hot spots and abnormal temperature rises in PV DC arcing cables.
•  The error rate is reduced to only 0.90°C, far superior to traditional methods.
•  The method provides real-time monitoring, enabling early warning of cable overheating and fire hazards.

7. Keywords

Photovoltaic DC Cable Monitoring, Non-Contact Temperature Measurement, Infrared Thermal Imaging, Overheating Detection, Cable Safety Monitoring

8. References

1. Hu Mengjie (2024). Heat Monitoring of Photovoltaic DC Arcing Cable Based on Non-Contact Temperature Measurement Technology. Wire & Cable, No.6, 2024. DOI: 10.16105/j.dxdl.1672-6901.202406006