Multiport Rogowski Coil Current Sensing With Adjacent Phase Rejection
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Solution Overview
Problem
Single Rogowski coil sensors fail to accurately measure current when an adjacent phase line or conductor is in a fault condition due to induced currents, leading to erroneous measurements.
Innovation Solution
A multiport current sensor system utilizing multiple Rogowski coil segments positioned around a monitored phase line, with each segment generating a voltage signal, and a combining circuit to add phase-aligned magnitudes, along with an adjacent phase rejection circuit to detect and reject interference from faulted adjacent phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single Rogowski coil sensor is used to measure current, then the device complexity is low, but measurement precision deteriorates due to interference from adjacent phase faults
Solution Approach 1:
The sensor divides the Rogowski coil into multiple segments (first Rogowski coil segment and second Rogowski coil segment) positioned at different locations around the monitored phase line. Each segment independently measures the magnetic field, and their outputs are combined to achieve both accurate current measurement and rejection of adjacent phase interference.
Solution Approach 2:
The patent combines the outputs of multiple Rogowski coil segments through a combining circuit that performs vector addition. This merging of multiple measurement signals allows the system to differentiate between current from the monitored phase and interference from adjacent phases, resolving the contradiction between measurement accuracy and device complexity.
2Measurement precision
If multiple Rogowski coil segments are used to improve measurement accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The Rogowski coil is segmented into multiple independent coil sections positioned at different angular positions around the conductor. Each segment provides an independent measurement channel, enabling the system to resolve current vectors and reject interference through mathematical combination of the segment outputs.
Solution Approach 2:
The system uses an adjacent phase rejection circuit that processes signals from multiple Rogowski coil segments and provides feedback to distinguish between legitimate current measurements and interference. The circuit analyzes the phase relationships and magnitude patterns to determine whether detected current originates from the monitored phase or adjacent phases.
3Adaptability or versatility
If the sensor operates near adjacent conductors, then adaptability improves, but reliability deteriorates due to induced currents from fault conditions
Solution Approach 1:
The patent converts the harmful effect of adjacent phase magnetic fields into useful information. By positioning multiple Rogowski coil segments at different locations, the system captures the spatial distribution of magnetic fields, including interference from adjacent phases. The combining circuit then uses this information to identify and reject interference, transforming what was previously a reliability problem into a solvable measurement challenge.
Solution Approach 2:
The combining circuit acts as an intermediary that processes raw signals from multiple Rogowski coil segments before producing the final current measurement. This intermediary stage performs vector addition and interference rejection, filtering out signals from adjacent phases while preserving accurate measurements of the monitored phase current, thereby ensuring reliability even when operating near adjacent conductors.
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 accurately measures current in the monitored phase line by filtering out interference from adjacent phase faults, preventing false tripping of breakers and improving measurement accuracy.
Implementation Method 1
A first Rogowski coil segment to generate a first voltage signal via a first port in response to current induced within the first Rogowski coil segment
Implementation Method 2
a combining circuit to add phase-aligned magnitudes
Implementation Method 3
an adjacent phase rejection circuit to detect and reject interference from faulted adjacent phases
Data Source
AI summary
A multiport current sensor is disclosed for measuring current. The sensor may include multiple CT or Rogowski coil segments or sections arranged in a closed loop configuration around a monitored phase line or other electrical conductor. An adjacent phase rejection circuit compares the magnitudes and/or phase angles of the voltage signals from the multiple coil segments. The adjacent phase rejection circuit may detect if a fault in an adjacent phase line or other electrical conductor is affecting the output signal of the current sensor by more than a threshold amount. The adjacent phase rejection circuit may additionally or alternatively indicate whether the measured values are valid for detecting a fault on the monitored phase line or other electrical conductor.