Capacitor Bank Impedance Monitoring for Fault Localization

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Solution Overview

Problem

Existing capacitor banks in electrical power systems face challenges in efficiently identifying and isolating failed or degraded capacitor units, leading to reduced system performance and increased downtime due to manual inspection requirements and potential cascading failures.

Innovation Solution

A monitoring system that uses time domain reflectometry (TDR) and impedance frequency response analysis to identify individual or groups of capacitor units with changed impedance, allowing for rapid localization and replacement of faulty units without manual inspection, and providing advanced warning for maintenance scheduling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If manual inspection methods are used to identify failed capacitor units, then system complexity is reduced, but identification time increases and system downtime increases

Engineering Contradiction:
Improveidentification timeVSAvoidmonitoring system complexity
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The patent replaces manual mechanical inspection with an automated electronic monitoring system that uses electrical signal injection and analysis to identify failed capacitor units. The system injects test signals into the capacitor bank and analyzes the electrical responses to automatically detect impedance changes indicating failures, eliminating the need for manual inspection while reducing identification time.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The monitoring system enables the capacitor bank to self-diagnose its own status by automatically injecting test signals and analyzing its own electrical responses. The system continuously monitors impedance changes and identifies failed units without external manual intervention, allowing the equipment to service itself through automated detection and reporting.

Inventive Principle:
Principle #25Self-service

2Reliability

If comprehensive monitoring of all capacitor units is implemented, then reliability improves, but device complexity increases

Engineering Contradiction:
Improvesystem reliabilityVSAvoidmonitoring system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the capacitor bank into individual monitorable units by injecting test signals that propagate through the bank and analyzing localized impedance responses. The system can identify and isolate specific failed capacitor units or strings rather than treating the entire bank as a single unit, enabling targeted monitoring that improves reliability while managing complexity through modular analysis.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The monitoring system detects failures by measuring changes in electrical parameters, specifically impedance, of capacitor units. By continuously monitoring impedance variations and comparing them against expected values, the system can identify failed units with high reliability. The use of multiple test frequencies allows the system to detect different types of failures and distinguish between healthy and degraded units.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If rapid identification of failed units is achieved through automated monitoring, then productivity improves, but use of energy increases

Engineering Contradiction:
Improvemaintenance efficiencyVSAvoidmonitoring system energy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The monitoring system uses periodic test signal injection at different frequencies to identify failed capacitor units. By applying test signals at multiple discrete frequencies and analyzing the responses, the system achieves comprehensive monitoring while managing energy consumption through controlled, periodic measurements rather than continuous high-power operation. The selective use of different frequencies allows efficient detection of various failure modes.

Inventive Principle:
Principle #19Periodic action

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 monitoring system reduces downtime by quickly identifying and isolating failed units, maintaining higher system efficiency, and enabling proactive maintenance to prevent cascading failures, thus improving the overall performance and reliability of the electrical power system.

Implementation Method 1

identify, based on the comparison and the information that specifies the spatially fixed configuration of the plurality of capacitor units of the capacitor bank, a group of capacitor units within the capacitor bank that have an impedance that is different from the nominal impedance of the group of capacitor units

Methodology Applied
Scientific EffectImpedance: Electrical Impedance Tomography

Data Source

PatentEP3341744B1Monitoring system for a capacitor bank
Publication Date: 2024.07.17 EATON INTELLIGENT POWER LTD
  • EP3341744B1 patent drawingFigure 1A
  • EP3341744B1 patent drawingFigure 1B
  • EP3341744B1 patent drawingFigure 2

AI summary

A first electrical response of a capacitor bank is accessed, the capacitor bank including a plurality of capacitor units arranged in a fixed spatial relationship with each other, each capacitor unit having a nominal impedance; a test electrical signal is provided to the capacitor bank; a second electrical response of the capacitor bank is measured after providing the test electrical signal to the capacitor bank; the first electrical response of the capacitor bank and the second response of the capacitor bank are compared; and whether an impedance of one or more capacitor units in the capacitor bank has changed relative to the nominal impedance is determined based on the comparison.