AC Filter Capacitor Health Diagnosis via Harmonic Current
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Solution Overview
Problem
Capacitors in FACTS devices degrade or fail over time due to process variations and environmental factors, affecting the performance of AC filters and causing harmonic distortion and voltage imbalances, with existing monitoring methods being offline and costly.
Innovation Solution
An electronic system and method for real-time capacitor health diagnosis using harmonic current analysis and capacitance monitoring, allowing for timely detection of failures or degradation without shutting down the AC switchyard, utilizing a controller to analyze harmonic currents and capacitance trends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If offline capacitor testing is performed to ensure accurate health assessment, then measurement precision is improved, but productivity deteriorates due to system shutdown requirements
Solution Approach 1:
The patent replaces physical offline testing methods with electronic harmonic current analysis. The controller measures harmonic currents generated by capacitor degradation and converts this electrical signal analysis into diagnostic information, eliminating the need for physical system shutdown and manual testing while maintaining diagnostic accuracy
Solution Approach 2:
The patent introduces harmonic current as an intermediary indicator of capacitor health. Instead of directly measuring capacitor parameters offline, the system uses harmonic current generation as a proxy signal that correlates with capacitor degradation, enabling indirect but accurate health assessment during normal operation
2Productivity
If real-time monitoring is implemented to improve productivity, then measurement precision deteriorates due to lack of offline testing capability
Solution Approach 1:
The patent implements continuous feedback monitoring of harmonic currents. The controller continuously measures harmonic current levels, compares them against baseline values, and updates capacitor health status in real-time, providing both continuous monitoring capability and accurate diagnosis through cumulative data analysis
Solution Approach 2:
The patent performs preliminary characterization of harmonic current patterns during normal operation. By establishing baseline harmonic current levels and degradation patterns during routine operation, the system prepares diagnostic criteria in advance that enable accurate real-time assessment without requiring separate offline testing sessions
3Reliability
If traditional offline testing methods are used to ensure reliability, then loss of time increases due to system shutdown and testing duration
Solution Approach 1:
The patent enables continuous capacitor health monitoring during normal FACTS device operation. The harmonic current analysis runs continuously without interruption, maintaining both the useful action of power transmission and the useful action of health monitoring simultaneously, eliminating downtime while ensuring reliability through ongoing assessment
4Measurement precision
If offline capacitor bank switching is performed to test individual capacitors, then measurement precision is improved for individual component assessment, but device complexity increases due to switching operations
Solution Approach 1:
The patent extracts the diagnostic function from the physical capacitor structure. Instead of requiring physical isolation or switching of individual capacitors, the system extracts diagnostic information through electrical signal analysis of harmonic currents, separating the measurement function from the mechanical switching infrastructure
Solution Approach 2:
The patent makes the monitoring system universal by designing it to work with capacitor banks in various configurations without requiring specific switching arrangements. The harmonic current analysis method applies universally to different capacitor bank topologies, eliminating the need for complex switching operations tailored to specific configurations
Data Source
AI summary
In an embodiment, an electronic circuit includes: one or more input terminals configured to receive measurement data; and a controller configured to: determine a first harmonic current based on a first current flowing through a first circuit coupled to a line node, where the measurement data includes first current data indicative of the first current, determine a filter harmonic current based on a filter current flowing through an AC filter coupled to the line node, where the measurement data includes filter current data indicative of the filter current, and generate a first flag indicative of failure, degradation or malfunction of a first capacitor or capacitor bank based on the first harmonic current and the filter harmonic current, where the AC filter includes the first capacitor or capacitor bank.