Transformer Winding Clamping Force Estimation via Vibration
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Solution Overview
Problem
Current methods for determining the clamping force on a transformer's winding package are invasive, require shutting down the transformer, and risk contamination, while existing non-invasive methods lack practicality for on-site assessment.
Innovation Solution
A method involving a current pulse excitation of the winding to measure vibrations and calculate the mechanical resonant frequency, allowing for estimation of clamping forces using a device with a current pulse generator, sensor, and computing unit, enabling on-site non-destructive diagnostics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inspection methods (measuring bolt torque, opening transformer tank) are used to determine clamping forces, then measurement capability is improved, but transformer operation is disrupted and contamination risk increases
Solution Approach 1:
The patent applies mechanical vibration by exciting the winding package with a current pulse and measuring the resulting vibrations to determine the mechanical resonant frequency. The clamping force is then inferred from this frequency, as it is dependent on the clamping force. This non-invasive vibration-based method allows measurement without opening the transformer tank or disrupting operation, resolving the contradiction between measurement capability and operational continuity.
2Difficulty of detecting and measuring
If the transformer tank is opened for inspection, then direct access to winding package is improved, but contamination risk and operational disruption increase
Solution Approach 1:
The patent replaces direct mechanical inspection (opening the tank to visually or physically examine the winding package) with an indirect measurement system. Electrical signals (current pulses) are used to excite the winding, and sensors measure vibrations externally. This substitution of mechanical inspection with electrical excitation and vibration measurement allows assessment without opening the tank, eliminating contamination risk while maintaining measurement capability.
3Measurement precision
If numerical methods or mathematical models are used to calculate mechanical resonant frequency, then theoretical accuracy is improved, but practical on-site applicability deteriorates
Solution Approach 1:
The patent implements self-service by having the transformer itself provide the measurement data needed. The winding package's own mechanical resonant frequency, which depends on clamping force, is directly measured through vibration excitation and detection. This eliminates the need for external mathematical models or laboratory-based calculations, enabling practical on-site measurement while maintaining theoretical accuracy through direct physical measurement of the system's inherent resonant frequency.
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
Enables accurate and practical estimation of clamping forces on transformers without disrupting operation or risking contamination, using a device that excites the desired vibration mode and calculates mechanical resonant frequency for determining clamping forces.
Implementation Method 1
supplying a current pulse to the winding in order to excite the winding
Implementation Method 2
measuring vibrations of the winding package generated by the current pulse
Implementation Method 3
measuring vibrations of the winding package generated by the current pulse
Implementation Method 4
the strongly non-linear strain-stress characteristic of the pressboard used in the transformer insulation gives rise to a mechanical resonant frequency that is dependent on the clamping forces on the windings
Data Source
Figure 1
Figure 2a~2c
Figure 3~4
AI summary
The present invention relates to a method and a device for estimating the winding clamping force on a winding package of a transformer or a reactor, the winding package comprising at least one winding (1) with connections (1a, 1b) and an iron core. The device comprises a current pulse generator (4) configured to generate a current pulse sufficient to excite the winding, means for supplying the current pulse to the winding, a sensor (6) for measuring vibrations of the transformer or the reactor generated by the current pulse, and a computing unit (8) configured to calculate said mechanical resonant frequency based on the measured vibrations and to estimate the clamping forces on the winding packages based on the calculated mechanical resonant frequency and a predetermined relation between the expected mechanical resonant frequency and the clamping force.