DC System Fault Detection via Impedance Spectroscopy
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Solution Overview
Problem
Fault detection and localization in DC systems with multiple serially connected sources is complex and time-consuming, often resulting in false positives or unclear results, especially when ground faults are present, and existing methods require individual configuration and reconfiguration of apparatuses, making them impractical for real-world applications.
Innovation Solution
A method and apparatus using impedance spectroscopy with a test AC signal applied to DC systems, allowing for fault detection and localization by comparing response signals with test signals, and employing a weak load and capacitive coupling to ensure non-destructive measurements, enabling the detection of multiple faults and their precise localization in a scalable manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If individual testing of each DC source is performed, then fault detection accuracy is improved, but time consumption increases significantly
Solution Approach 1:
The system segments the fault detection task by using signal injection at different locations (positive terminal, negative terminal, and ground) to independently characterize different fault types. Each measurement configuration targets specific fault segments, allowing parallel assessment of multiple potential fault locations without physically testing each component individually.
Solution Approach 2:
The test apparatus is designed with multi-functionality to perform multiple measurement configurations using the same hardware. The system can switch between different test signal injection points and measurement modes, enabling a single device to accomplish what would otherwise require multiple specialized testing apparatuses.
2Measurement precision
If additional setup including DC BIAS is used for fault localization, then fault localization capability is improved, but device complexity increases
Solution Approach 1:
The system uses the DC system's own operational characteristics and existing ground references to perform fault localization. Instead of requiring external DC BIAS equipment, the method leverages the natural voltage potentials and ground connections already present in the DC system during normal operation, making the system self-sufficient for diagnostic purposes.
3Measurement precision
If analysis in time domain reflectometry is used, then fault detection capability is improved, but procedure complexity increases
Solution Approach 1:
The system replaces complex time domain reflectometry analysis with a simpler frequency domain impedance spectroscopy approach. By measuring impedance magnitude and phase across a frequency spectrum and analyzing the characteristics through equivalent circuit modeling, the method achieves fault detection and localization without requiring sophisticated signal processing algorithms or specialized analysis equipment.
4Measurement precision
If multiple apparatuses are connected and disconnected for different measurements, then comprehensive fault detection is improved, but ease of operation deteriorates
Solution Approach 1:
The test apparatus is designed as a universal multi-functional device that integrates multiple measurement capabilities into a single unit. It can perform impedance spectroscopy, signal injection, and various measurement configurations all through one apparatus, eliminating the need to connect and disconnect multiple specialized devices while maintaining comprehensive fault detection coverage.
5Device complexity
If conventional LCR meter is used without considering ground faults, then simplicity is improved, but reliability deteriorates due to false positives
Solution Approach 1:
The system applies different measurement strategies tailored to specific measurement locations and fault types. By injecting test signals at different points (positive terminal, negative terminal, ground) and analyzing the local impedance characteristics, the method accurately distinguishes between genuine faults and artifacts caused by ground connections, eliminating false positives while maintaining measurement simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method provides reliable and precise detection and localization of faults, reducing the complexity of diagnosing faults in large DC systems like PV arrays, allowing for efficient identification of faulty components and preventing production losses and hazards, while being safe and practical for field use.
Implementation Method 1
comparing the response AC signal with the test AC signal to detect a fault and the location of the fault in the DC-system by means of impedance spectroscopy
Implementation Method 2
employing a weak load and capacitive coupling to ensure non-destructive measurements
Data Source
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AI summary
This disclosure relates to a method of and a system for fault detection and localisation of a fault in a DC-system comprising multiple serially connected DC-sources. The method may comprise an act of connecting a test apparatus to at least one terminal of the DC-system and to DC-system ground. The method encompasses at least one repetition of an act of applying a test AC-signal to one terminal of the DC-system, an act of detecting the response AC-signal to the test AC-signal on either one terminal alone and/or on DC-system ground; and an act of comparing the test AC signal with the response AC-signal to detect a fault and the location of the fault in the DC-system. The system comprises a fault detection and localisation apparatus configured to perform the method disclosed.