Phase-to-Earth Fault Location via Voltage Drop Curve Intersection
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Solution Overview
Problem
Existing fault localization algorithms in electric networks struggle to accurately locate single-phase earth faults, especially in high impedance earthed systems, due to factors like fault resistance and load distribution, leading to significant errors in fault location estimation.
Innovation Solution
The method involves determining the equivalent load distance of an electric line, which models the total load as a single point, allowing for improved fault localization by using a voltage drop profile and equivalent load distance curve, enhancing the accuracy of fault location and tolerance to load current variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If impedance-based fault location algorithms are used, then implementation is easy and short-circuit faults are localized satisfactorily, but low current earth faults cannot be localized accurately
Solution Approach 1:
The invention changes the fundamental parameter used for fault location from impedance-based calculations to voltage drop profile analysis. By measuring voltage drops at different points along the line and comparing them to a pre-stored voltage drop curve, the method can accurately locate both short-circuit faults and low current earth faults, overcoming the limitation of traditional impedance-based algorithms while maintaining ease of implementation through the use of standard measurement signals.
2Device complexity
If fault location is assumed to be in front of the load point, then calculation is simplified, but accuracy is impaired when loads are distributed or located at the beginning of the feeder
Solution Approach 1:
Instead of assuming the fault location and calculating expected measurements, the invention inverts the approach by measuring actual voltage drops and comparing them against a pre-established voltage drop curve that represents the entire line length. This allows the fault location to be determined directly from the measurement comparison, eliminating the need to assume fault position relative to load points and accurately handling cases where loads are distributed or located at the beginning of the feeder.
3Adaptability or versatility
If traditional fault localization methods are used in high impedance earthed systems, then standard algorithms can be applied, but significant errors occur due to fault resistance and load effects
Solution Approach 1:
The invention fundamentally changes the measurement parameter from impedance to voltage drop, which is particularly effective for high impedance earthed systems. By measuring voltage drops at the beginning and end of the line during a fault condition and comparing these measurements to a pre-stored voltage drop curve, the method can accurately locate faults even in the presence of high fault resistance and varying load conditions, achieving both versatility and precision.
Data Source
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AI summary
A method and apparatus for determining a location of a phase-to-earth fault on a three-phase electric line (30) of an electric network, comprising determining an equivalent load distance curve of the electric line (30) representing a voltage drop along the electric line scaled by an equivalent load distance of the electric line, determining a fault distance line indicating an estimate of a distance of the fault (F) from the measuring point (40) in relation to the equivalent load distance, determining a distance at which the equivalent load distance curve and the fault distance line intersect when superimposed, and selecting the determined distance as the distance between the measuring point (40) and the point of fault (F).