Self-Calibrating Non-Contact Voltage Sensor for Transmission Lines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing non-contact capacitive voltage monitors for AC power transmission lines are less accurate due to dielectric instability and require direct electrical connection, which is costly and risky, and existing solutions fail to provide reliable self-calibration under varying physical and environmental conditions.
Innovation Solution
A non-contact, self-calibrating AC voltage sensor system using capacitive elements with a self-calibrating probe capacitance acquisition sub-system and an auto-ranging capacitive voltage divider measurement sub-system, which includes a variable reference capacitor and a controller to adjust the voltage divider ratio, allowing for accurate voltage measurement without breaking the insulation barrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct electrical connection is used for voltage measurement, then measurement reliability is improved, but installation cost and risk increase
Solution Approach 1:
The patent introduces capacitive elements as intermediary components that couple to the transmission line without direct electrical connection. These capacitors serve as mediators between the high-voltage line and the measurement circuit, enabling voltage sensing while maintaining electrical isolation and eliminating the need for direct contact with live conductors.
Solution Approach 2:
The patent replaces traditional direct electrical connection (mechanical contact-based measurement) with a capacitive coupling system. This substitution eliminates the need for physical contact with the transmission line, thereby reducing installation complexity and safety risks while maintaining measurement capability through electric field interaction.
2Ease of manufacture
If non-contact capacitive measurement is used, then installation cost and risk are reduced, but measurement precision deteriorates due to dielectric instability
Solution Approach 1:
The patent implements a self-calibration system where the measurement circuit automatically compensates for dielectric instability. The system uses internal reference capacitors and calibration routines that continuously adjust for variations in the dielectric properties of the transmission line insulation, eliminating the need for external calibration and maintaining measurement precision despite environmental changes.
Solution Approach 2:
The patent incorporates feedback mechanisms through the self-calibration system that monitors measurement deviations caused by dielectric instability and automatically corrects them. The system uses feedback from reference measurements and environmental sensors to adjust calibration parameters in real-time, compensating for dielectric variations and maintaining measurement accuracy.
3Measurement precision
If self-calibration capability is added, then measurement precision under varying conditions is improved, but device complexity increases
Solution Approach 1:
The patent designs the capacitive measurement system to perform multiple functions: voltage measurement, self-calibration, and environmental compensation all within a single integrated circuit. The capacitive elements serve both as sensing elements and as part of the calibration reference system, reducing the need for separate components and simplifying the overall device architecture.
Solution Approach 2:
The patent merges the measurement and calibration functions into a unified system. The same capacitive elements used for voltage measurement are also utilized in the self-calibration process, and the control circuit integrates both measurement and calibration operations. This consolidation reduces component count and simplifies the device structure while maintaining high measurement precision under varying conditions.
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
The system provides accurate AC voltage measurement on transmission lines despite varying conditions, reducing installation costs and risks by maintaining non-contact operation and enabling real-time capacitance auto-calibration.
Implementation Method 1
a probe capacitance acquisition sub-system including a probe capacitor C2 for measuring a capacitance value of the measurement capacitor Cmeasure
Implementation Method 2
a voltage divider including the measurement capacitor and a reference capacitor coupled to a ground connection, and wherein the voltage measurement system is configured to calculate the third value related to the voltage level of the transmission line using a voltage divider ratio based on the second value and a capacitance of the reference capacitor
Implementation Method 3
an isolated power supply configured to provide power to the capacitance acquisition system. In one embodiment the isolated power supply includes an inductive current clamp transformer configured to be coupled around the transmission line and to provide power to the capacitance acquisition system
Data Source
Figure 1
Figure 2
Figure 3
AI summary
According to one aspect, embodiments described herein provide a sensor comprising a housing configured to be coupled around a portion of the transmission line, at least one probe capacitor configured to encircle the portion of the transmission line with the housing coupled around the portion of the transmission line, a measurement capacitor configured to encircle the portion of the transmission line with the housing coupled around the portion of the transmission line, a capacitance acquisition system, and a voltage measurement system, wherein the capacitance acquisition system is configured to determine a first value related to capacitance of the at least one probe capacitor, and based on the first value, determine a second value related to capacitance of the measurement capacitor, and wherein the voltage measurement system is configured to receive a signal providing the second value and calculate a third value related to a voltage level of the transmission line.