Generator Breaker Failure Detection via Reverse Power Monitoring

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Solution Overview

Problem

Existing breaker failure detection systems in electrical generators fail to accurately detect failures, especially at low current conditions, leading to potential damage and unintended operation due to reliance on generator circuit breaker status indicators, which are inadequate for low current outputs.

Innovation Solution

A system and method that determine breaker failure by monitoring active and reactive power thresholds, turbine valve closure, and issuing trip commands to generator circuit breakers without relying on status indicators, using sensors and a controller to detect reverse active and reactive power conditions and initiate retrip commands if thresholds are not met.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If breaker failure detection relies on generator circuit breaker status indicators, then the detection system is simple to implement, but the detection accuracy deteriorates at low current conditions

Engineering Contradiction:

Improvedetection system complexityVSAvoidbreaker failure detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary detection mechanism that monitors power flow characteristics (active and reactive power thresholds) as a mediator between the breaker operation and failure detection. Instead of directly relying on breaker status indicators, the system uses power flow measurements as an intermediary signal to infer breaker state, thereby improving detection accuracy without significantly increasing system complexity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical/electrical status indicator system with an electronic power measurement-based detection system. By substituting the traditional mechanical breaker position indicators with electronic monitoring of active and reactive power thresholds, the system achieves higher measurement precision while maintaining reasonable complexity through software-based analysis

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If breaker failure detection uses traditional status indicators, then the system operation is straightforward, but the reliability of detection deteriorates for low current fault conditions

Engineering Contradiction:

Improvedetection operation simplicityVSAvoidbreaker failure detection reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent implements preliminary action by establishing power flow thresholds and detection criteria before actual breaker failure occurs. The system pre-configures active and reactive power thresholds that indicate potential breaker failure conditions, allowing it to detect issues at early stages before they manifest as complete failures, thereby improving reliability while maintaining straightforward operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent incorporates feedback mechanisms where the detection system continuously monitors power flow characteristics and compares them against predetermined thresholds. This feedback loop provides continuous verification of breaker operation, improving reliability by detecting deviations from normal operation while keeping the system easy to operate through automated threshold comparison and alert generation

Inventive Principle:

Principle #23Feedback

3Productivity

If the generator continues operation after breaker failure, then productivity is maintained, but harmful effects increase due to unintended operation as induction motor

Engineering Contradiction:

Improvegenerator operation continuityVSAvoiddamage from unintended induction motor operation

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by implementing protective measures that prevent the harmful effects of unintended induction motor operation before they occur. The detection system identifies breaker failure conditions and triggers protective actions (such as alarm signals or automatic shutdown sequences) that counteract the potential damage, allowing the system to maintain productivity only when safe to do so while preventing harmful operation

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS11368113B2Breaker failure protection using reverse active power and negative reactive power element

Publication Date: 2022.06.21 SCHWEITZER ENGINEERING LABORATORIES INC

AI summary

A generator system includes a generator including terminals, a generator circuit breaker coupled to the terminals and that couples and decouples the generator from a power grid, multiple sensors, and a controller that operates the generator system. The controller determines whether an active power is less than a reverse active power threshold and whether one or more turbine valves are closed, and determines that a breaker failure has occurred based on the active power being less than the reverse active power threshold and the one or more turbine valves being closed. If the active power remains less than the reverse active power and the turbine valves remain closed after a threshold time period after the trip command, and if a reactive power is less than a reverse reactive power threshold, then a breaker failure has occurred. In response, the controller may transmit another trip command to the generator circuit breaker to initiate the breaker failure protection.