Stator Winding Fault Localization via Power Ratio Analysis
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Solution Overview
Problem
Existing methods for diagnosing faulty winding sets in generators, particularly in wind turbines, are inefficient as they fail to accurately locate the faulty phase during operation, leading to prolonged downtime and complex service interventions due to high resistance connections and other faults.
Innovation Solution
A method and system that calculates individual power ratios for each wire in a winding set, forming diagnostic values by comparing these ratios to identify faulty phases without requiring thresholds, allowing for online condition monitoring and precise fault localization in generators, including those with high resistance connections and short-circuit turns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
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 the faulty phase cannot be localized and service time is prolonged
Solution Approach 1:
The patent segments the diagnostic process into two distinct phases: first detecting the presence of a fault in the winding set, then localizing the specific faulty phase. This is achieved by calculating individual power ratios for each phase and comparing them to identify which specific phase has the abnormal ratio, thereby pinpointing the faulty phase without requiring inspection of all connections.
Solution Approach 2:
The patent performs preliminary fault detection during generator operation using power ratio analysis before service intervention is required. By continuously monitoring and comparing individual power ratios of different phases, the system preliminarily identifies which phase is faulty, preparing the information needed for rapid targeted repair.
2Measurement precision
If all connections in a winding set are inspected to locate the faulty phase, then accurate fault localization is achieved, but service complexity and downtime increase
Solution Approach 1:
The patent extracts the diagnostic function from physical inspection by using electrical measurements (power ratios) to identify the faulty phase. Instead of taking out and physically inspecting each connection, the system extracts information about the faulty phase through mathematical analysis of power ratios, thereby simplifying the service intervention to only the identified phase.
Solution Approach 2:
The patent replaces the mechanical inspection process with an electrical measurement and calculation system. By substituting physical inspection of all connections with electrical power ratio analysis, the system achieves automatic fault localization without manual intervention, reducing service complexity and downtime.
3Ease of operation
If threshold-based diagnostic methods are used, then fault detection is simplified, but false alarms increase reducing reliability
Solution Approach 1:
The patent changes the diagnostic parameter from absolute power values to relative power ratios between phases. This parameter transformation eliminates the need for threshold settings because the diagnosis is based on comparing phases against each other rather than against fixed thresholds, thereby reducing false alarms while maintaining operational simplicity.
4Loss of time
If online diagnostic methods are implemented during generator operation, then downtime is reduced, but measurement accuracy may be affected by operational variations
Solution Approach 1:
The patent exploits the asymmetry or imbalance in power ratios between phases as the diagnostic indicator. Under normal operation, power ratios should be balanced; when a fault occurs, an asymmetric pattern emerges in the power ratios of the faulty phase. This approach actually benefits from operational variations because the fault creates a distinct asymmetric signature that stands out against the balanced background.
Data Source
AI summary
Provided is a method of diagnosing at least one winding set of a stator of a generator during operation, the winding set having plural wires for plural phases, the method including: obtaining, for each of the plural wires of the winding set, an individual strength of an individual power output from the respective wire of the plural wires of the winding set; obtaining a sum strength of power; forming, for each considered wire of the plural wires of the winding set, an individual ratio between the individual strength of the considered wire and the sum strength; forming, for each considered wire of the plural wires of the winding set, a diagnostic value by subtracting from an individual ratio not corresponding to the considered wire a term depending on the individual ratio corresponding to the considered wire; diagnosing at least one wire based on comparing the diagnostic values.