Cable Fault Location Using Protection Relay Data
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Solution Overview
Problem
The challenge in accurately locating faults in underground cables, especially in urban areas, is exacerbated by the need for expensive sensors, trial-and-error excavations, and the influence of fault resistance, leading to disruptions and high costs.
Innovation Solution
A fault locating system that uses existing protection relays to extract voltage and current data from cable segments, aligning disturbance data, calculating fitness values, and iteratively refining the fault location using discrete Fourier transforms and search algorithms, eliminating the need for additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If expensive sensors and detectors are deployed along the cable path to pinpoint fault location, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the fault location detection function from specialized expensive sensors and implements it using the existing protection relay system that is already deployed at cable terminals. The relay's voltage and current measurement capabilities are utilized to calculate fault location, eliminating the need for additional sensors along the cable path.
Solution Approach 2:
The protection relay, originally designed for cable protection and monitoring, is made multi-functional by enabling it to perform fault location detection. The same relay hardware and measurement channels used for protection purposes are repurposed to determine fault position, eliminating the need for dedicated fault location sensors.
2Reliability
If trial and error-based excavations are performed on both sides of estimated fault location, then fault detection capability is improved, but loss of time and productivity decrease
Solution Approach 1:
The patent replaces the mechanical trial-and-error excavation process with an electrical measurement-based calculation system. By using voltage and current data from protection relays and applying computational algorithms, the exact fault location is determined mathematically, eliminating the need for physical trial excavations.
Solution Approach 2:
The fault location is calculated and determined before any excavation work begins. The protection relays continuously monitor cable parameters, and upon fault detection, the system immediately computes the fault position, allowing excavation to start directly at the precise location without preliminary trial digging.
3Reliability
If trial and error excavations are performed to locate faults, then fault detection capability is improved, but object-affected harmful factors increase due to disruptions to population
Solution Approach 1:
The patent replaces mechanical excavation with electrical measurement and calculation. By determining fault location through voltage and current data analysis from protection relays, the system eliminates the need for disruptive trial excavations in urban areas, thereby avoiding harm to the surrounding population and environment.
4Measurement precision
If fault resistance is considered in location estimation techniques, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs an iterative feedback-based calculation approach where the protection relay measurements are processed through algorithms that account for fault resistance effects. The system uses the measured voltage and current data, along with cable parameters, to calculate fault location while compensating for the influence of fault resistance, achieving accurate results without additional sensors.
Data Source
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AI summary
The present invention relates to system and method for detecting location of fault in a cable (101). System receives disturbance data (117, 119) from first protection relay (111) and second protection relay (113) when one of the first protection relay and/or the second protection relay detect fault in a section of the cable. System extracts voltage and current data for each segment in the section using the disturbance data, cable parameters and length of each segment. System determines a fitness value for each segment in the section using the extracted voltage and current data. Thereafter, system identifies a segment with a lowest fitness value from the fitness value determined for each segment in the section by comparing the fitness value of each segment with the fitness value of subsequent segments in the section and detects the segment with the lowest fitness value as fault location in the cable.