Brushless Exciter Fault Detection via Harmonic Admittance
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Solution Overview
Problem
Existing methods for detecting faults in rotating diodes of brushless synchronous generators are complex, require multiple sensors, and are slow to respond, making them inadequate for preventing damage during diode failures.
Innovation Solution
A method that uses a single sensor to measure characteristic values of the exciter armature winding, calculating the positive sequence third harmonic admittance and impedance to rapidly detect faults in the rectifier circuit, allowing for fast and accurate identification of diode failures without modifying the existing circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage sensors are used to measure diode voltage and determine voltage ratios for fault detection, then fault detection capability is improved, but device complexity increases due to requiring 12 separate voltage sensors and series connected diodes
Solution Approach 1:
The invention extracts only the necessary measurement information (voltage drops across two specific diodes D1 and D3) from the rectifier circuit, rather than measuring all diode voltages. This selective extraction reduces the sensor count from 12 voltage sensors to just 2 sensors while maintaining fault detection capability through the ratio V_D1/V_D3 analysis.
Solution Approach 2:
The voltage sensors are configured to perform multiple functions: they measure voltage drops across individual diodes for fault detection, and their measurements are used to calculate the voltage ratio that indicates fault conditions. The same sensing infrastructure supports both normal operation monitoring and fault detection, eliminating the need for dedicated fault detection hardware.
2Reliability
If fast and accurate diode failure detection is implemented, then reliability is improved, but device complexity increases due to additional sensors and circuit modifications
Solution Approach 1:
The rectifier circuit itself provides the measurement signals needed for fault detection. The voltage drops across the diodes during normal operation are directly used as the measurement signals, eliminating the need for separate measurement circuits or additional hardware. The circuit's own operating parameters serve as the fault detection indicators.
Solution Approach 2:
The invention monitors changes in the voltage ratio parameter V_D1/V_D3 to detect fault conditions. By focusing on this specific parameter relationship rather than absolute voltage values, the system achieves fast and accurate fault detection while using minimal sensing infrastructure. The ratio parameter provides robust fault indication across varying operating conditions.
Data Source
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AI summary
A method for detecting a fault in an exciter circuit, suitable for use in a brushless generator, the exciter circuit including (a) an exciter armature winding, having a plurality of armatures, arranged to generate a multiphase AC signal, each armature of the plurality of armatures providing a respective sub-signal component of the multiphase AC signal, and (b) a rectifier circuit for receiving the sub-signals via the respective armatures, the rectifier circuit comprising a plurality of components arranged to rectify the sub-signals to provide a rectified output signal, wherein the method includes the steps of: acquiring a respective operational sub-value for a first characteristic of each of at least two of the respective sub-signals; deriving an operational value indicative of a relationship between the acquired respective operational sub-values; determining whether a fault has occurred in the exciter circuit on the basis of the derived operational value.