Fault Location in Multi-Conductor Power Supply Lines
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Solution Overview
Problem
Existing methods for determining fault locations in power supply systems with multiple conductors, especially in autotransformer systems, face ambiguity due to non-linear distance-reactance curves, leading to multiple possible error locations and requiring time-consuming network reconfiguration or additional equipment for accurate fault localization.
Innovation Solution
A method that determines the most likely fault location by comparing measured resistance and fault current values with pre-known curves, using a deviation metric to minimize errors and avoid reconfiguration, allowing for direct fault location without reconnection or additional devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If autotransformer systems are used for railway power supply, then voltage drops are reduced and spacing between substations is increased, but the distance-reactance curve becomes non-linear leading to multiple possible fault locations
Solution Approach 1:
The patent transitions from using a single reactance measurement (one dimension) to combining reactance measurement with directional current analysis (adding temporal and spatial dimensions). By measuring currents in multiple directions and comparing them with stored reference data, the system resolves the ambiguity of multiple possible fault locations into a precise single location identification.
Solution Approach 2:
The system uses feedback by comparing measured fault current directions with pre-stored reference current patterns for different fault locations. This feedback mechanism allows the protective relay to identify which reference pattern matches the actual fault conditions, thereby determining the precise fault location despite the non-linear characteristics of autotransformer systems.
2Measurement precision
If network reconfiguration is performed to locate faults, then fault location accuracy is improved, but network availability is reduced due to time-consuming reconfiguration
Solution Approach 1:
The patent applies preliminary action by pre-storing reference current patterns and reactance data for all possible fault locations in the system before actual faults occur. During a fault event, the protective relay simply needs to compare measured values against these pre-existing references, eliminating the need for time-consuming network reconfiguration and enabling immediate fault location identification.
Solution Approach 2:
The system performs self-service by using its own existing measurement capabilities and pre-stored data to locate faults without requiring external intervention or network reconfiguration. The protective relay independently compares measured currents and reactance values with reference data to determine fault location, maintaining network availability while achieving accurate fault identification.
3Measurement precision
If additional equipment is installed for fault location, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by enabling the existing protective relay to perform multiple functions: normal protection operations plus fault location identification. By utilizing the relay's existing current measurement and reactance calculation capabilities, combined with pre-stored reference data, the system achieves precise fault location without requiring separate dedicated fault location equipment, thereby avoiding increased device complexity.
Data Source
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Figure 5~6
AI summary
The present invention relates to a method for determining a fault location (9) in the event of a short circuit along a power supply line with multiple conductors, comprising the steps of: - determining a resistance (7) and a fault current at a measuring point of the power supply line; - comparing the determined resistance (7) with a previously known resistance profile (1, 2, 3) for each conductor to determine at least one possible fault location (8, 9, 10); - calculating a deviation between an expected fault current and the determined fault current for each possible fault location, wherein the expected fault current is determined based on a previously known fault current profile (4, 5, 6) for each conductor; - defining the fault location (9) as the fault location with the smallest deviation.Furthermore, the present invention relates to an arrangement for determining the location of a fault in the event of a short circuit along a power supply line with several conductors.