Partial Discharge Measurement via I/Q Mixing
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Solution Overview
Problem
Existing partial discharge measurement systems in high-voltage installations face challenges in distinguishing real partial discharge signals from environmental noise, particularly in noisy environments, which affects the accuracy and robustness of the measurements.
Innovation Solution
A method and device utilizing I/Q mixing to generate in-phase and quadrature signals from electrical signals, followed by low-pass filtering and processing with a low-frequency Analog-Digital converter, allowing for precise detection of partial discharge pulses and differentiation from noise, while operating at lower costs with off-the-shelf components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional band-pass filtering and envelope detection are used according to IEC 60270 standard, then the measurement system can operate at low frequency, but the system cannot effectively distinguish real partial discharge signals from environmental noise in noisy environments
Solution Approach 1:
The patent transforms the signal processing approach by using I/Q mixing to convert the partial discharge signal from a single-dimensional amplitude measurement to a two-dimensional representation with both in-phase and quadrature components. This dimensional expansion enables phase-based discrimination between genuine partial discharge signals and noise, resolving the contradiction between low-frequency operation and noise immunity.
Solution Approach 2:
The patent changes the processing parameters by introducing phase information through I/Q mixing, transforming the signal representation from simple amplitude envelope detection to complex I/Q plane analysis. This parameter change allows the system to maintain low-frequency operation while gaining the ability to distinguish signals from noise through phase characteristics.
2Measurement precision
If I/Q mixing is used to distinguish signals from noise, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent introduces I/Q mixing as an intermediary processing step that converts the raw partial discharge signal into in-phase and quadrature components. This intermediary transformation simplifies the subsequent noise discrimination task by organizing the signal information in a structured I/Q plane, making the overall system more manageable despite the added mixing stage.
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
The approach enhances the robustness of partial discharge measurements by distinguishing real signals from noise, providing precise data acquisition and improved detection capabilities in noisy environments, thus improving the reliability of partial discharge monitoring in medium- and high-voltage systems.
Implementation Method 1
Generating an in-phase and a quadrature-signal from the electrical signal which comprises the partial discharge pulses in an I/Q-mixer unit by mixing the electrical signal which comprises the partial discharge pulses with two local oscillator signals, which have the same frequency and a phase difference of 90°
Implementation Method 2
Filtering each of the in-phase and the quadrature signals with a low-pass filter
Data Source
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AI summary
A method and device for determining partial discharge in an electrical insulation system of a medium- or high voltage apparatus is disclosed with: Detecting, with a sensing unit, an electrical signal that comprises partial discharge pulses due to dielectric breakdowns in the electrical insulation system of the medium- or high voltage apparatus; generating an in-phase and a quadrature-signal from the electrical signal comprising the partial discharge pulses in an I/Q-mixer unit by mixing the electrical signal comprising the partial discharge pulses with two local oscillator signals having the same frequency and a phase difference of 90°; Filtering each of the in-phase and the quadrature signals with a low-pass filter; Processing the filtered in-phase and the quadrature signals in a processing unit with a low-frequency Analog-Digital converter to obtain digital signals representing an in-phase and a quadrature value.