Multi-phase Fault Location in Ungrounded Power Distribution Systems
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Solution Overview
Problem
Existing methods for locating multi-phase faults in ungrounded power distribution systems are costly due to the need for additional measurement devices and often rely on approximate line models, leading to potential errors in fault location determination.
Innovation Solution
The method uses measurements from feeder breakers and switches to determine the faulty feeder section and line type by analyzing voltage and current measurements, employing one-ended or two-ended algorithms based on available measurements, and incorporating three-phase circuit analysis to accurately locate faults without assuming fault impedance, thus avoiding errors related to line modeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional fault measurement devices are installed along the power distribution system, then fault location measurement capability is improved, but system cost increases
Solution Approach 1:
The existing protection relays and measurement devices in the power distribution system are utilized to perform fault location functions. The system serves itself by using already-installed equipment (feeder breakers and switches with integrated sensors) to detect and locate faults, eliminating the need for additional dedicated fault measurement devices.
Solution Approach 2:
The existing measurement devices and protection relays are made multi-functional by enabling them to perform both their original protection functions and new fault location functions. The same sensors and measurement systems used for routine monitoring are also utilized for fault detection and localization, maximizing the utility of existing infrastructure.
2Device complexity
If approximate line models are used for fault location calculation, then calculation complexity is reduced, but fault location accuracy deteriorates
Solution Approach 1:
The fault location methodology transitions from using simplified approximate line models to using exact line models with precise parameters. By incorporating accurate line impedance values, exact fault location calculations are performed, eliminating approximation errors while maintaining computational feasibility through systematic solution approaches.
Solution Approach 2:
The approximate analytical methods are replaced with more rigorous mathematical models and computational algorithms. The system substitutes simplified mechanical approximations with precise electrical circuit analysis based on exact line parameters, achieving higher accuracy through enhanced computational approaches.
Data Source
AI summary
A method determines a location of a fault in a faulty feeder section of an ungrounded power distribution system based on a type of the fault and the type of the faulty line. The method determines, if the faulty line is the lateral and the fault is phase-to-phase or double-phase-to-ground fault, the fault at a first point on an un-faulty phase of the lateral where a fault current equals a load current. The method determines, if the faulty line is the lateral and the fault is the three-phase fault, the location of the fault at a point with a minimal difference between imaginary parts of equivalent fault impedances. The method determines, if the faulty line is the mainline, the location of the fault at a point partitioning the faulty segment on two sub-segments with a ratio of lengths determined based on the voltages at the buses of the faulty segment.