Combined Current and Voltage Sensor for High Voltage Power Lines
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Solution Overview
Problem
Conventional current transformers and voltage sensors for high voltage electric power transmission and distribution systems face issues such as excessive heating, limited current carrying capacity, separate power requirements, electromagnetic interference, and susceptibility to cross talk, which hinder effective measurement and communication in smart grid applications.
Innovation Solution
A combined current and voltage electric power sensor system with an onboard energy harvesting power supply and wireless communication device, featuring a foil patch voltage sensor, current sensing coil, and energy harvesting coil, housed within a Faraday cage and corona ring to minimize interference, allowing for simultaneous measurement and transmission of current and voltage data without physical contact with the power line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional CTs are placed in physical contact with the monitored power line conductor, then current measurement is achieved, but excessive heating occurs and current carrying capacity is limited
Solution Approach 1:
The patent introduces an optical intermediary (light) between the current transformer and the power line conductor. The CT measures current without physical contact by detecting the magnetic field through optical means, eliminating direct thermal contact while maintaining measurement capability. This resolves the contradiction by using light as a mediator that transfers measurement information without transferring heat.
2Measurement precision
If conventional CTs are used for current measurement, then current data is obtained, but separate voltage sensors and power supplies are required
Solution Approach 1:
The patent combines the current transformer, voltage sensor, power supply, and communication devices into a single integrated monitoring device. The CT and voltage sensing elements are housed together with shared power and communication infrastructure, eliminating the need for separate installations. This merging reduces device complexity while maintaining both current and voltage measurement capabilities.
3Measurement precision
If conventional voltage sensors are used, then voltage measurement is achieved, but they are susceptible to electromagnetic interference and cross talk
Solution Approach 1:
The patent uses the electromagnetic field that causes interference as the measurement mechanism itself. The voltage sensor detects voltage by measuring the electromagnetic field around the power line, and the system distinguishes the desired signal from interference through directional sensing and signal processing. The corona ring also utilizes controlled electromagnetic discharge to protect against surges. This converts the harmful electromagnetic environment into a useful measurement medium.
4Volume of moving object
If foil patch voltage sensors are used, then device size is reduced, but susceptibility to cross talk increases
Solution Approach 1:
The patent introduces a dielectric barrier (air gap or insulating material) between the foil patch sensor and the power line. This intermediary layer reduces direct capacitive coupling that causes cross talk while maintaining sufficient electric field interaction for voltage measurement. The corona ring also acts as an intermediary that controls electromagnetic discharge patterns to reduce interference.
5Measurement precision
If conventional voltage sensors are used, then accurate measurement is achieved, but they are physically large and expensive
Solution Approach 1:
The patent changes the fundamental measurement parameter from direct electrical contact (conventional sensors) to electromagnetic field detection (foil patch capacitive sensing). This parameter change enables the use of thin, flexible foil patches instead of bulky mechanical sensors, dramatically reducing size while maintaining measurement accuracy through proper field coupling geometry and signal processing.
6Measurement precision
If environmental temperature compensation is implemented, then measurement accuracy is maintained, but system cost and complexity increase
Solution Approach 1:
The patent implements self-compensation through the physical design of the sensor system. The foil patch sensor and corona ring are configured to naturally compensate for temperature effects through their geometric relationships and material properties. The system uses inherent physical characteristics rather than active electronic compensation circuits, achieving temperature stability through passive self-regulation. This reduces complexity while maintaining accuracy.
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, robust, and cost-effective measurement of AC currents and voltages with reduced electromagnetic interference, enabling real-time monitoring and control in smart grid applications, enhancing the current carrying capacity and reducing maintenance needs.
Implementation Method 1
A current sensing coil disposed in the flange surrounding the aperture measures an electric current flowing in the monitored power line
Implementation Method 2
An electronics board disposed in the base carries a foil patch voltage sensor that measures an electric voltage on the monitored power line
Implementation Method 3
A power supply coil disposed in the flange surrounding the aperture harvests electric power from the monitored power line
Implementation Method 4
A Faraday cage may shield the current sensing coil and the electronics board from electromagnetic interference from sources other than the power line
Implementation Method 5
A corona ring may be positioned adjacent to the base
Data Source
AI summary
A high voltage electric power line monitor includes a current sensor, a voltage sensor, an energy harvesting power supply, and a communication device. The monitor is supported by an overhead power line support structure, such an insulator housing a sectionalizing switch. The current sensor coil and the energy harvesting coils are positioned transverse to the power line with the power lane passing through the coils. A foil patch voltage sensor and a communications antenna are carried on an electronics board positioned parallel to the monitored power line, typically below the current sensor. Both the current sensor and the voltage sensor are positioned adjacent to, but spaced apart from, the monitored power line creating an air gap between the monitor and the power line. The sensors are housed within a Faraday cage to shield the current sensor from electromagnetic contamination.