Feeder Fault Location Using Source-Substation Signal Analysis
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Solution Overview
Problem
Existing methods for locating single-phase faults in medium-voltage networks, particularly those with compensated or impedance-neutral systems, are imprecise and require costly equipment or extensive network modifications, failing to accurately identify the faulty branch in complex networks.
Innovation Solution
A method that utilizes measurements at the head of the faulty feeder to estimate fault distance and resistance by applying Fortescue transformation and Takagi's equation, decomposing the network into sections, and using matrix models to determine symmetrical components and fault currents, without requiring additional equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fault passage indicators are deployed in different locations to identify the faulty branch, then the ability to locate faults in branched networks is improved, but the cost and device complexity increase significantly
Solution Approach 1:
The invention extracts the fault detection function from multiple distributed indicators and concentrates it into a single measurement point at the source station. By measuring only the fundamental frequency current and voltage at the source station, the system eliminates the need for multiple fault passage indicators while maintaining the ability to identify the faulty branch through signal analysis.
Solution Approach 2:
The measurement system at the source station performs multiple functions simultaneously: it measures fundamental frequency quantities for power system operation, harmonic quantities for quality monitoring, and fault location information for protection. This multi-functionality eliminates the need for separate fault passage indicators, reducing device complexity while maintaining measurement precision.
2Measurement precision
If measurements are taken at the head of each feeder and at the neutral point, then the accuracy of fault current estimation is improved, but the measurement setup complexity and cost increase
Solution Approach 1:
The invention extracts only the essential measurements needed for fault location (fundamental frequency current and voltage at the source station) and discards the requirement for multiple measurement points. The method uses signal processing techniques to derive sufficient information from minimal measurements, eliminating complex measurement setups while maintaining estimation accuracy.
Solution Approach 2:
The system uses the existing measurement infrastructure at the source station (already in place for power system operation) to perform fault location functions. The measurement system serves itself by utilizing available data (fundamental frequency quantities) for multiple purposes including fault location, eliminating the need for additional dedicated measurement equipment.
3Device complexity
If simplifying assumptions are applied to the network model, then the complexity of parameter estimation is reduced, but the fault location precision deteriorates
Solution Approach 1:
The invention changes the approach from estimating physical network parameters (impedances, admittances) to directly estimating fault location using signal processing techniques. By working with fundamental frequency current and voltage measurements and applying Fortescue transformation, the method avoids complex parameter estimation while achieving precise fault location through mathematical relationships in the frequency domain.
4Measurement precision
If a high sampling frequency of 10 MHz is used, then the precision of fault location is improved, but the cost of measuring equipment increases
Solution Approach 1:
The invention changes the frequency domain of operation from high-frequency transient analysis (10 MHz) to fundamental frequency analysis (50/60 Hz). By focusing on the fundamental frequency components of the fault signal and using synchronous sampling techniques, the method achieves accurate fault location using standard power system measurement equipment rather than expensive high-speed sampling systems.
Data Source
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AI summary
The invention relates to a method for locating a fault affecting a phase of a faulty feeder of an electrical distribution network, comprising the following steps: - obtaining an electrical signal at the time of the fault, the electrical signal being measured (MES) at a source substation (PS) of the network only for the faulty feeder; - examination of sections (TR1, TR2, TR3, TR4, TRn) of the faulty feeder, each section having a head and a tail, and the examination of a section comprising: o from the electrical signal obtained, the estimation of a fault current at the tail of the section and the calculation of a distance of the fault from the head of the section; o the calculation of a difference between the estimated distance and a length separating the head from the tail of the section; and o depending on said difference, the identification or not of a solution for locating the fault.