Transformer Impedance Monitoring via Load-Dependent Coefficients
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Solution Overview
Problem
Current on-line transformer impedance monitoring methods are inaccurate for diagnostic purposes due to computational complexity and neglect of magnetizing current, which is crucial for determining transformer properties like impedance and turn ratio.
Innovation Solution
A method that collects measurements of transformer load currents and AC signals to derive coefficients for relations between quantities and transformer loads, allowing for accurate on-line monitoring and diagnosis of transformer properties such as impedance, turn ratio, and magnetizing current, using equations like ΔV=Z1*I0+Zw*I2 and I1=1/n*I2, reflecting impedances to determine transformer status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional off-line impedance measurement methods are used, then measurement accuracy is sufficient, but transformer operation is interrupted and replacement is costly
Solution Approach 1:
The patent replaces conventional off-line impedance measurement methods with an on-line monitoring system that uses voltage and current sensors to continuously monitor transformer impedance during operation. The system substitutes direct physical measurement with computational analysis of electrical parameters (voltage E and current A) to derive impedance values, enabling continuous monitoring without interrupting transformer operation.
Solution Approach 2:
The patent introduces an intermediary computational model that processes voltage and current measurements to derive impedance values. Instead of directly measuring impedance, the system uses the relationship between measurable quantities (voltage E, current A) and the target quantity (impedance Z) through the equation Z=E/A, acting as an intermediary calculation layer that enables indirect but accurate measurement during operation.
2Device complexity
If simplified impedance models are used for on-line monitoring, then computational complexity is reduced, but measurement accuracy becomes insufficient for diagnostic purposes
Solution Approach 1:
The patent implements a dynamic impedance monitoring system that continuously updates impedance values based on real-time voltage and current measurements. The system adapts to changing operational conditions by recalculating impedance at different load levels, capturing the dynamic behavior of transformer impedance rather than relying on static simplified models. This dynamic approach maintains accuracy across varying operating conditions.
Solution Approach 2:
The patent segments the impedance measurement process into multiple independent calculations for different phases and time points. Instead of attempting to measure all impedance parameters simultaneously, the system divides the measurement into separate voltage and current measurements, then combines them computationally. This segmentation allows for more accurate individual measurements that are then synthesized into comprehensive impedance values.
3Loss of information
If comprehensive 9×9 impedance matrix calculation is performed, then complete transformer status information is obtained, but computational complexity increases significantly
Solution Approach 1:
The patent applies partial action by selectively measuring and calculating only the specific impedance parameters needed for diagnostic purposes, rather than computing the complete 9×9 impedance matrix. The system focuses on extracting relevant information (such as self-impedance and mutual impedance values) through targeted measurements and calculations, reducing computational burden while maintaining diagnostic effectiveness.
Solution Approach 2:
The patent extracts essential impedance information from the complex 9×9 matrix calculation by identifying and isolating the specific parameters needed for transformer diagnostics. The system takes out only the critical impedance values (such as Z11, Z22, and mutual impedance terms) that provide meaningful diagnostic information, discarding redundant calculations while preserving the essential transformer status data.
Data Source
AI summary
A transformer diagnosis apparatus and method which can advantageously be used for on-line diagnosis of a transformer, and by which transformer properties may be monitored and/or determined. The diagnosis method includes collecting, for at least two different transformer loads, measurements of a current being indicative of the transformer load, as well as measurements of at least one further transformer AC signal. The method further includes deriving, from the collected measurements, at least two values of a quantity which depends on a transformer property as well as on transformer load; and determining, from the derived values, a set of coefficient(s) of a relation for how the quantity is expected to vary with transformer load. The method further includes using the determined coefficient(s) in performing a diagnosis of the transformer.