Partial Discharge Detection Bandwidth Expansion via Signal Aliasing
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Solution Overview
Problem
Conventional partial discharge detection boards struggle to accurately detect high-frequency signals above the Nyquist frequency due to the presence of anti-aliasing filters, which limit their ability to distinguish and measure the full extent of partial discharges in electrical insulation systems.
Innovation Solution
A partial discharge detection board design that omits the anti-aliasing filter, using a voltage divider and buffer to attenuate frequencies above an upper cutoff frequency, allowing the analog-to-digital converter to capture signals up to this frequency, and a high-pass filter to remove lower frequencies, enabling more accurate detection of partial discharges by processing a broader range of signal frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an anti-aliasing filter is used to remove signal portions above the Nyquist frequency, then the ADC can accurately convert signals without aliasing, but the detection board cannot distinguish or measure signals above the Nyquist frequency
Solution Approach 1:
The patent removes the anti-aliasing filter from the signal path, extracting the constraint that previously prevented high-frequency signal detection. This allows the ADC to receive and process signals above the Nyquist frequency, capturing previously lost high-frequency partial discharge information while managing aliasing through software or post-processing methods.
Solution Approach 2:
The patent changes the sampling frequency parameter of the ADC to a higher value (e.g., 200 MHz or 250 MHz), which raises the Nyquist frequency and enables the system to detect higher frequency signals. This parameter change allows the detection board to capture a broader frequency range of partial discharge signals.
2Measurement precision
If the sampling rate is increased to capture higher frequencies, then signals above the original Nyquist frequency can be detected, but the complexity of the detection board increases
Solution Approach 1:
The patent employs an FPGA (Field-Programmable Gate Array) that can perform multiple functions: it serves as the ADC control unit, implements digital filtering, processes signals, and manages data output. This multi-functional approach increases detection capability without proportionally increasing physical hardware complexity, as the FPGA can be reprogrammed to handle different sampling rates and processing requirements.
Solution Approach 2:
The patent replaces analog anti-aliasing filters with digital signal processing methods implemented in the FPGA. Instead of using physical analog components to filter signals before ADC conversion, the system uses digital filtering algorithms to process signals after conversion, reducing the need for complex analog circuitry and allowing flexible adjustment of filtering parameters through software.
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 precise measurement of partial discharge strength by capturing and amplifying frequencies above the Nyquist frequency, enhancing the detection of insulation system failures before catastrophic damage occurs.
Implementation Method 1
A voltage divider is configured to attenuate a voltage of the reflected signal
Implementation Method 2
The buffer attenuates frequencies of the reflected signal that are greater than an upper cutoff frequency
Implementation Method 3
the analog-to-digital converter converts the reflected signal from an analog domain to a digital domain
Implementation Method 4
The filter attenuates frequencies of the reflected signal that are less than a lower cutoff frequency
Data Source
AI summary
A partial discharge detection board includes a voltage divider configured to attenuate a voltage of a reflected signal. A buffer is connected to the voltage divider. The buffer attenuates frequencies of the reflected signal that are greater than an upper cutoff frequency. An analog-to-digital converter is connected to the buffer. The analog-to-digital converter receives portions of the reflected signal up to the upper cutoff frequency, and the analog-to-digital converter converts the reflected signal from an analog domain to a digital domain. A filter is connected to the analog-to-digital converter. The filter attenuates frequencies of the reflected signal that are less than a lower cutoff frequency. A comparator is connected to the filter. The comparator compares the voltage of the reflected signal to a reference voltage. A counter is connected to the comparator. The counter increments when the voltage of the reflected signal is greater than the reference voltage.