High Voltage Capacitor Pack Monitoring with Impedance Sensors
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Solution Overview
Problem
Conventional methods for monitoring high voltage capacitors in electric power systems lack effective detection of partial failures, leading to conservative replacement practices that can result in system downtime and costly maintenance, especially during peak electricity consumption periods, as they cannot determine single or distributed capacitor failures within a bank.
Innovation Solution
A capacitor status monitor that attaches across the bushings of a capacitor container, detecting internal impedance to identify single capacitor pack failures, using radio transmitters and visual indicators, and communicates with a remote transmission unit to schedule maintenance, allowing for proactive replacement without taking the entire bank out of service.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional monitoring methods are used to detect capacitor failures, then system simplicity is maintained, but detection precision is insufficient to identify single capacitor pack failures
Solution Approach 1:
The invention segments the monitoring function by providing individual status monitors for each capacitor pack rather than monitoring the entire bank as a single unit. Each monitor independently detects failures in its associated capacitor pack, enabling precise identification of single pack failures without requiring complex bank-wide monitoring systems.
Solution Approach 2:
The invention introduces an intermediary status monitor device that bridges the gap between simple conventional monitoring and complex detailed analysis. The status monitor acts as a mediator that provides precise failure detection capability while maintaining system simplicity by being a self-contained unit that attaches to existing capacitor pack terminals.
2Reliability
If capacitor canisters are replaced only after multiple internal failures occur, then maintenance cost is reduced, but system reliability deteriorates due to prolonged operation with degraded capacitors
Solution Approach 1:
The invention enables preliminary detection of single capacitor failures before they propagate to multiple failures. By detecting and addressing single failures early, the system prevents the need for costly emergency replacements during peak operation and avoids the reliability degradation that occurs when operating with degraded capacitor banks.
Solution Approach 2:
The status monitor provides continuous feedback on the health status of each capacitor pack, enabling proactive maintenance scheduling. This feedback mechanism allows operators to plan replacements during off-peak periods when cost is lower, rather than being forced into expensive emergency replacements when failures occur during high-demand periods.
3Measurement precision
If capacitor bank is taken out of service for testing, then detection precision is improved, but productivity is reduced due to system downtime
Solution Approach 1:
The status monitor enables self-service monitoring of capacitor pack health without requiring the capacitor bank to be taken out of service. The monitor continuously assesses the operational status of each capacitor pack while the bank remains energized, eliminating the need for productivity-reducing shutdowns for testing while maintaining high detection precision.
4Ease of manufacture
If conservative replacement practices are used, then maintenance cost is reduced, but loss of time increases due to system downtime during peak periods
Solution Approach 1:
The status monitor enables preliminary identification of failed capacitor packs, allowing operators to schedule replacements during off-peak periods when the impact of downtime is minimized. This proactive approach transforms unplanned emergency replacements during high-cost peak periods into planned maintenance activities during low-cost off-peak periods, reducing both time loss and associated costs.
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
Enables early detection of single capacitor pack failures, reducing the risk of explosive failures and minimizing downtime by allowing for proactive replacement during off-peak hours, thus providing a cost-effective and efficient monitoring system for high voltage capacitors.
Implementation Method 1
A capacitor pack status monitor includes a current sensor measuring an electric current through an associated capacitor pack
Implementation Method 2
a voltage sensor measuring an electric voltage across the associated capacitor pack
Data Source
AI summary
A high voltage capacitor includes multiple capacitor packs housed in a canister. A capacitor pack status monitor includes a current sensor measuring an electric current through an associated capacitor pack and a radio transmitting a first signal representative of the electric current through a selected capacitor pack. The monitor also includes a voltage sensor measuring an electric voltage across the associated capacitor pack and a radio transmitting a second signal representative of the electric voltage across the selected capacitor pack. Electronics compute an impedance associated with each capacitor pack. Each current sensor may include a current transformer positioned around a main power line energizing a respective capacitor pack. Each voltage sensor may include a relatively large high voltage discharge resistor connected across the respective capacitor pack, and a relatively small voltage measurement resistor connected in series with the relatively large high voltage discharge resistor across the respective capacitor pack.