Multi-winding Stator Fault Detection via Second Harmonic Power

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Solution Overview

Problem

Existing methods for diagnosing faults in multi-stator generators, such as high resistance connections and short-circuit turns, are not reliable for online monitoring and often generate false alarms, posing a risk to wind turbines due to their complexity and sensitivity to transients and inherent asymmetries.

Innovation Solution

A method that monitors the second harmonic power difference between multiple winding sets of a generator during operation, using active and reactive power components to diagnose faults like high resistance connections and short-circuit turns, while accounting for inherent asymmetries and transients, allowing for robust and sensitive fault detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional diagnostic methods (visual inspections, standstill tests, negative sequence analysis) are used to detect high resistance connections, then fault detection capability is provided, but false alarms increase and reliability decreases during online operation

Engineering Contradiction:

Improvefault detection reliabilityVSAvoidfault detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent changes the monitoring parameter from conventional methods (negative sequence components, zero sequence voltages) to second harmonic power components. By analyzing the second harmonic content of active and reactive power produced by each winding set, the method achieves more reliable fault detection during online operation with reduced false alarms, as the second harmonic power difference directly reflects asymmetries caused by high resistance connections

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces offline mechanical inspection methods and complex signal analysis with a simplified electrical parameter-based diagnostic approach. Instead of using visual inspections, standstill resistance measurements, or complex negative sequence analysis, the method uses straightforward power measurement and second harmonic extraction during normal generator operation, substituting complex diagnostic procedures with a more reliable electrical parameter monitoring system

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If complex diagnostic methods are implemented for online monitoring, then fault detection capability improves, but device complexity increases

Engineering Contradiction:

Improveonline monitoring capabilityVSAvoidmonitoring system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts only the essential second harmonic power component from the complex power signal produced by each winding set. By focusing specifically on the second harmonic content rather than analyzing the entire power spectrum or using complex multi-parameter analysis, the method achieves reliable online monitoring with simplified processing requirements, reducing device complexity while maintaining high reliability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses the existing power measurement infrastructure of the generator control system to perform fault diagnosis. The same sensors and processors used for normal generator control and power management are utilized to extract second harmonic power components for diagnostic purposes, making the monitoring system universal and avoiding additional dedicated diagnostic hardware, thereby reducing overall system complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If conventional fault detection methods are used, then some faults can be detected, but sensitivity to transients and inherent asymmetries causes false alarms

Engineering Contradiction:

Improvefault detection sensitivityVSAvoidfalse alarm rate

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent exploits the asymmetry introduced by faults (high resistance connections) in the multi-winding stator system. By comparing the second harmonic power components between different winding sets, the method specifically targets asymmetric fault signatures while being insensitive to symmetric transient variations and inherent system asymmetries, thereby achieving high sensitivity to actual faults with low false alarm rates

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent applies a threshold-based diagnostic approach where the second harmonic power difference is compared against a predetermined threshold value. This partial action method provides sufficient sensitivity to detect faults without requiring complex adaptive thresholding or extensive signal processing, effectively filtering out transient effects and inherent asymmetries that would cause false alarms while maintaining reliable fault detection

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11165379B2Monitoring a multi-winding set stator

Publication Date: 2021.11.02 SIEMENS GAMESA RENEWABLE ENERGY AS

AI summary

A method of monitoring a first winding set and at least one second winding set of a stator of a generator during operation is provided. The method includes: obtaining a first strength of a second harmonic of a first power produced from the first winding set; obtaining a second strength of a second harmonic of a second power produced from the second winding set; diagnosing the first winding set and/or the second winding set based on a second harmonic power difference between the first strength and the second strength.