Single-Phase Broken Conductor Detection Using Sequence Currents
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Solution Overview
Problem
Conventional methods for detecting single-phase broken conductors in power systems suffer from low accuracy and high costs, posing risks to system stability, human safety, and potential wildfires.
Innovation Solution
A method and system utilizing three-phase current analysis to detect single-phase broken conductors by calculating changes in positive and negative sequence currents and voltages, with predetermined thresholds to accurately identify and distinguish downstream faults from other system anomalies, employing a relay action when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods for detecting single-phase broken conductors are used, then detection coverage is provided, but accuracy is low and cost is high
Solution Approach 1:
The patent transforms the detection approach by changing the parameters analyzed from traditional methods to positive sequence current and negative sequence current. By calculating the ratio of changes in these sequence currents and comparing against predetermined thresholds, the system achieves high accuracy detection without requiring complex or expensive equipment, thus resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent replaces complex mechanical or traditional detection systems with an electrical parameter-based detection method. By substituting physical measurement mechanisms with electrical current analysis (positive and negative sequence currents), the system achieves cost-effective high-accuracy detection, eliminating the need for expensive hardware while maintaining superior measurement precision
2Measurement precision
If downstream fault detection is implemented, then fault isolation accuracy is improved, but detection time is increased due to additional verification steps
Solution Approach 1:
The patent performs preliminary actions by first determining whether a broken conductor fault occurs based on current sequence analysis before initiating the more time-consuming voltage-based downstream fault verification. This staged approach allows the system to quickly identify obvious faults while reserving time-intensive verification for cases where downstream fault determination is needed, thus balancing accuracy improvement with time loss
Data Source
AI summary
The present disclosure provides a method, a device and a system for detecting a single-phase broken conductor. The method includes: collecting a three-phase current at a measurement point; obtaining a positive sequence current and a negative sequence current from the collected three-phase current; calculating a change of the positive sequence current and a change of the negative sequence current within a first time interval; and when an amplitude of the positive sequence current decreases, an amplitude of the negative sequence current increases, a decrease of the amplitude of the positive sequence current is greater than a first predetermined value, and a ratio of a magnitude of change of the negative sequence current to a magnitude of change of the positive sequence current is greater than a second predetermined value, determining that a first set of faults occur, the first set of faults including a single-phase broken conductor.