Partial Discharge Location Using Passive Ferrite Reflection
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Solution Overview
Problem
Existing methods for on-line partial discharge detection in power cables require two active units, leading to high costs, maintenance issues, and lower accuracy due to synchronization and data communication errors, making them unreliable and inefficient for real-time monitoring.
Innovation Solution
A single master measuring unit is used in conjunction with a passive element, such as a ferrite core, to detect direct and reflected pulses, allowing for accurate distance calculation of partial discharges without synchronization, reducing costs and improving reliability by using time difference measurements and noise suppression techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two active measurement units are used for on-line partial discharge detection, then measurement coverage and reliability are improved, but system cost, complexity, and maintenance requirements increase
Solution Approach 1:
The patent extracts the reflection function from the measurement system and implements it using a passive element (ferrite core) rather than requiring a second active measurement unit. This separates the detection function (performed by the single active unit) from the reflection function (performed by the passive ferrite core), thereby reducing system complexity while maintaining measurement reliability through the use of reflected pulses.
Solution Approach 2:
The patent introduces a passive ferrite core as an intermediary element that provides impedance reflection without requiring active control or power supply. This intermediary component enables the system to generate reflected pulses necessary for location determination while avoiding the complexity of synchronizing multiple active units, thus resolving the contradiction between reliability and complexity.
2Measurement precision
If two active measurement units are used for on-line partial discharge detection, then measurement accuracy is improved, but synchronization errors and data communication errors increase
Solution Approach 1:
The patent extracts the synchronization and data communication functions from the measurement system by using a single active unit combined with a passive reflection element. This eliminates the sources of synchronization errors and data communication errors between multiple units, while maintaining location measurement accuracy through time difference measurement of reflected pulses.
Solution Approach 2:
The passive ferrite core element automatically provides the reflection function without requiring active control, synchronization, or data communication with other units. This self-service approach eliminates information loss from synchronization and communication errors while maintaining measurement precision through local pulse reflection and time difference measurement.
3Adaptability or versatility
If two active measurement units are used for on-line partial discharge detection, then system functionality is improved, but placement and maintenance costs increase
Solution Approach 1:
The patent extracts the active measurement functionality into a single unit and combines it with a passive reflection element. This reduces the number of components that require placement and maintenance from two active units to one active unit and one passive element, thereby reducing costs while maintaining measurement functionality through the use of reflected pulses for location determination.
Solution Approach 2:
The patent replaces the expensive and maintenance-intensive second active measurement unit with a cheap passive ferrite core element that requires no power supply, has no moving parts, and needs no maintenance. This substitution maintains the necessary measurement functionality while dramatically reducing placement and maintenance costs.
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
This approach enables cost-effective, reliable, and accurate on-line partial discharge detection in power cables during normal operation, reducing maintenance needs and avoiding costly breakdowns by pinpointing defects before they cause electrical failures.
Implementation Method 1
detecting a direct pulse originating from a partial discharge in the power cable
Implementation Method 2
detecting a reflected pulse originating from the same partial discharge, the reflected pulse being reflected by an impedance change at a second location of the power cable
Data Source
Figure 1~2
Figure 3~4
AI summary
Method and on-line measurement system for on-line measurement in a power cable (1). The power cable (1) has a conductor (2), a dielectric (3) and a conductive earth sheet (4). A master measuring unit (10) is provided at a first location along the power cable (1). During normal operation of the power cable (1) the following steps are executed: - detecting a direct pulse (Pd) originating from a partial discharge (PD) in the power cable (1); - detecting a reflected pulse (Pr) originating from the same partial discharge (PD), the reflected pulse being reflected by an impedance change (11) at a second location of the power cable (1); and - determining the distance (y) of the partial discharge (PD) from the second location using a time difference measurement between the direct pulse detection and the reflected pulse detection, and a pulse travelling speed (s) in the power cable (1).