Insulation Condition Analysis of Electrical Machines Using High-Frequency Signals
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Solution Overview
Problem
Current methods for monitoring and detecting insulation deterioration in electrical machines are limited by the need for de-energization, interference from noise and electromagnetic signals, and the high cost and complexity of existing FRA systems, which restrict their use in energized machines and multiple grounding configurations.
Innovation Solution
A system that injects and measures high-frequency voltage signals between the conductors and housing of electrical machines, using Sweep Frequency Response Analysis (SFRA) and the Absolute Sum of Logarithmic Error (ASLE) statistical indicator to assess insulation condition without interfering with power supply or grounding, allowing continuous monitoring across various voltage levels and grounding types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional FRA systems are used to monitor insulation condition, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The system divides the insulation monitoring task into phase-specific measurements. Instead of measuring all phases simultaneously with a complex system, the injection module injects signals into one phase at a time, and the measurement module measures the current in that phase, allowing simplified sequential monitoring of multiple phases
Solution Approach 2:
The patent uses an intermediary statistical indicator (ASLE - Absolute Sum of Logarithmic Error) to compare measured impedance spectra with reference spectra. This intermediary metric simplifies the complex comparison process and provides a clear quantitative measure of insulation deterioration without requiring complex analysis systems
2Productivity
If FRA systems are applied to energized machines, then productivity is improved by avoiding shutdowns, but measurement precision deteriorates due to noise and electromagnetic interference
Solution Approach 1:
The system performs preliminary measurements of the phase current spectrum before injecting the test signal. This allows the measurement module to distinguish between the normal operating current components and the injected high-frequency test signal components, enabling accurate impedance measurement even in energized conditions
Solution Approach 2:
The system uses high-frequency voltage signals (above 1 kHz) that are significantly higher than the power frequency (50/60 Hz). This parameter separation in frequency domain allows the measurement module to isolate the test signal response from the background electromagnetic noise and operating current, maintaining measurement precision during energized operation
3Adaptability or versatility
If multiple grounding configurations are supported, then adaptability is improved, but device complexity increases due to interference from ground paths
Solution Approach 1:
The system extracts and measures only the high-frequency current component that flows through the phase conductor during signal injection. By focusing measurement on this specific current component rather than total current, the system eliminates interference from ground path currents and other parallel paths, enabling compatibility with multiple grounding configurations without increased complexity
4Measurement precision
If high-frequency signals are injected into power supply conductors, then measurement precision is improved for insulation assessment, but harmful factors increase due to electromagnetic interference with other equipment
Solution Approach 1:
The injection module applies high-frequency voltage signals in a periodic, controlled manner rather than continuously. The signal is injected only during brief measurement intervals when the measurement module is actively measuring current. This periodic action minimizes electromagnetic interference with other equipment while still providing accurate insulation impedance measurements during the measurement windows
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 non-invasive, scalable, and cost-effective monitoring of insulation deterioration in energized electrical machines, reducing the risk of unscheduled downtime and improving reliability, while avoiding the need for user specialization and minimizing machine stoppages.
Implementation Method 1
a scanning module (20) configured to inject and measure a plurality of high-frequency voltage signals between the electrical machine housing and the plurality of conductors
Implementation Method 2
measure a plurality of high-frequency currents circulating in the plurality of conductors in response to the injection of each of the plurality of high-frequency voltage signals
Data Source
AI summary
The present invention relates to a system for analyzing the insulation condition of an electrical machine (1), the electrical machine (1) comprising a housing (2), a plurality of supply conductors (3) and at least one grounding branch (5), in which it comprises: at least one scanning module (20) coupled to the plurality of conductors (3); at least one control module (9) coupled to the scanning module (20); and at least one analysis module (21) coupled to the control module (9); wherein the scanning module (20) is configured to inject and measure a plurality of high frequency voltage signals between the housing (2) of the electrical machine (1) and the plurality of conductors (3) and measure a plurality of high frequency currents circulating in the plurality of conductors (3) in response to the injection of each of the plurality of high frequency voltage signals; wherein the control module (9) is configured to control and synchronize the injections and measurements of the scanning module (20) and send the measurement data to the analysis module (21); wherein the analysis module (21) is configured to process the data received from the control module (9) and determine the condition of the insulation by calculating statistical indicators of the frequency response of the electrical machine (1). The present invention also comprises a method for analyzing the insulation condition of an electrical machine (1) using the system according to the present invention. Finally, the present invention comprises a storage medium comprising a set of instructions for carrying out the method according to the present invention.