Excess Voltage Drop Detection in Three-Phase AC Circuits
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Solution Overview
Problem
Existing methods for detecting excess voltage drops in three-phase AC circuits are costly and invasive, often requiring offline inspections with dedicated sensing devices, which do not provide real-time monitoring and can lead to equipment damage and efficiency losses due to improper electrical connections.
Innovation Solution
A diagnostic system that includes a processor to analyze three-phase voltages and currents, compute positive, negative, and zero sequence currents, extract a compensated negative sequence current, and determine fault reference current phasors to identify and localize excess voltage drop faults in three-phase AC circuits, allowing for online detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If periodic thermal inspection using IR scanners is performed, then detection accuracy of electrical connection faults is improved, but inspection cost and system complexity increase significantly
Solution Approach 1:
The electrical distribution system uses its own operational parameters (voltage and current) to detect faults, eliminating the need for external inspection equipment. The system self-diagnoses by analyzing its own three-phase electrical parameters to identify excess voltage drops and improper connections.
Solution Approach 2:
The patent extracts only the essential detection function from complex inspection systems. Instead of using full-featured IR scanners or other dedicated sensing devices, it isolates and analyzes specifically the three-phase voltage and current parameters to detect faults, simplifying the detection mechanism while maintaining effectiveness.
2Reliability
If dedicated sensing devices are used for inspection, then fault detection capability is improved, but online monitoring capability deteriorates as inspections must be performed offline
Solution Approach 1:
The diagnostic system continuously monitors the three-phase electrical parameters during normal system operation, providing uninterrupted fault detection. The analysis is performed on ongoing voltage and current data, enabling continuous detection without interrupting the electrical distribution system's operation.
3Object-affected harmful factors
If periodic inspection maintenance is performed, then safety against overheated contacts is improved, but productivity and system availability decrease due to downtime
Solution Approach 1:
The system performs preliminary detection of improper electrical connections and excess voltage drops during normal operation, before conditions deteriorate to dangerous levels. By continuously monitoring electrical parameters, the system can identify and alert operators to potential issues before they cause overheating, equipment damage, or fires, eliminating the need for scheduled shutdowns for inspection.
4Measurement precision
If comprehensive inspection of all electrical connections is performed, then detection coverage is improved, but inspection time and cost increase
Solution Approach 1:
The diagnostic system provides universal monitoring coverage for all three-phase electrical connections simultaneously through a single analysis process. By analyzing the three-phase voltage and current parameters, the system detects faults across all phases and connections in unison, achieving comprehensive coverage without requiring multiple separate inspection procedures or extended time periods.
Data Source
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AI summary
A system and method for detecting excess voltage drop (EVD) in a three-phase electrical distribution circuit includes a diagnostic system comprising a processor that is programmed to receive three-phase voltages and currents provided to terminals of the electrical machine, determine fundamental components of the three-phase voltages and currents provided to the terminals, and compute positive, negative, and zero sequence currents from the fundamental components. The processor is also programmed to extract a compensated negative sequence current from the negative sequence current component, add the compensated negative sequence current to the positive sequence current to determine fault reference current phasors, determine a negative current reference phase angle for each phase based in part on a phase angle of the positive sequence current, and identify an EVD fault in the electrical distribution circuit based on the compensated negative sequence current, the fault reference current phasors, and the negative current reference phase angles.