Transformer Diagnostics via Multi-Frequency Excitation Current Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High voltage transformers face challenges in diagnostic testing due to capacitive components of excitation current distorting expected patterns, making it difficult to determine normal or abnormal characteristic signatures.
Innovation Solution
A system and method that apply AC voltages at different frequencies to a transformer's winding or phase, measure the resulting excitation currents, and compare them to benchmark transformers' currents to determine electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If AC voltage is applied at power frequency to measure excitation current, then diagnostic testing can be performed, but the capacitive component of excitation current distorts the expected patterns making conclusions less certain
Solution Approach 1:
The patent changes the frequency parameter of the applied voltage from power frequency (60 Hz) to a higher frequency (e.g., 1 kHz). This parameter change eliminates the capacitive component distortion that plagues power frequency measurements, allowing for more accurate measurement of the inductive component of excitation current and improving diagnostic reliability.
Solution Approach 2:
The patent segments the excitation current measurement into two distinct components by measuring at two different frequencies. The first frequency measurement captures the inductive component, while the second frequency measurement captures both inductive and capacitive components. By subtracting the first from the second, the capacitive component is isolated and can be removed from the analysis, leaving only the diagnostically relevant inductive component.
2Reliability
If routine diagnostic testing is performed to detect transformer issues, then catastrophic failures can be minimized, but the testing process is time-consuming and requires transformer downtime
Solution Approach 1:
The patent applies partial action by using a reduced voltage level (e.g., 120V or 240V) compared to full operating voltage, which is sufficient to obtain diagnostic measurements without requiring full transformer operation. This allows diagnostics to be performed with minimal impact on system operations and reduces the time transformers need to be taken offline.
Solution Approach 2:
The patent performs preliminary diagnostic testing before catastrophic failures occur by regularly measuring excitation current characteristics. This preliminary detection of insulation degradation, turn-to-turn shorts, and other issues allows for proactive maintenance scheduling, preventing unexpected failures and reducing overall downtime by addressing issues before they become critical.
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
This approach allows for more complete diagnostic analysis of transformers, enabling identification of defects or normal operation by matching current patterns with those of benchmark transformers.
Implementation Method 1
applying a voltage output of a voltage generator to a winding or phase of the target transformer; controlling the voltage generator to output an AC voltage at a first frequency and then a second frequency and measuring first and second excitation currents flowing into the target transformer
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A method for performing diagnostics on a target transformer includes applying a voltage output of a voltage generator to a winding or phase of the target transformer; controlling the voltage generator to output an AC voltage at a first frequency and then a second frequency and measuring first and second excitation currents flowing into the target transformer associated with the first frequency and second frequency, respectively. The method further includes determining an actual excitation current of the target transformer as a function of both the first and second excitation currents, and comparing the actual excitation current of the target transformer to excitation currents associated with one or more benchmark transformers having known electrical characteristics. And when the actual excitation current of the target transformer matches an excitation current of one of benchmark transformers, determining the electrical characteristics of the target transformer to match electrical characteristics of the one benchmark transformer.