Wind Turbine Grid Oscillation Detection Across Split FFT Ranges
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Solution Overview
Problem
Detecting low-frequency oscillations in electrical supply grids, particularly subsynchronous resonances, is challenging due to their low amplitude and frequency, which can be masked by noise and interference, and requires long measurement periods, making quick and accurate detection difficult.
Innovation Solution
A method involving two series of measurements with different frequency ranges and sampling rates is proposed, using Fast Fourier Transform (FFT) for frequency analysis to identify low-frequency oscillations, with a longer measurement period and lower sampling rate for lower frequencies and a shorter period with higher sampling rate for higher frequencies, allowing for quicker detection of oscillations within the upper frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a long measurement period is used to detect low-frequency oscillations, then detection accuracy is improved, but detection speed deteriorates
Solution Approach 1:
The frequency spectrum is segmented into multiple frequency ranges (e.g., first frequency range with lower frequencies and second frequency range with higher frequencies). Different measurement periods are assigned to different frequency ranges: longer measurement periods for lower frequencies and shorter measurement periods for higher frequencies. This allows accurate detection of low-frequency oscillations while maintaining fast detection capability for higher frequency components.
2Productivity
If a single high sampling rate is used for the entire frequency range, then detection speed is improved, but measurement complexity and data processing burden increase
Solution Approach 1:
Different sampling rates are applied to different frequency ranges based on local requirements. Higher sampling rates are used for higher frequency ranges where fast detection is critical, while lower sampling rates are used for lower frequency ranges where longer measurement periods are already employed. This optimizes the balance between detection speed and measurement complexity for each frequency band.
3Adaptability or versatility
If multiple frequency ranges are analyzed simultaneously, then comprehensive detection capability is improved, but processing time increases
Solution Approach 1:
The detection process is segmented into parallel frequency range analyses. Each frequency range is processed independently with its own optimized measurement period and sampling rate. This parallel segmentation allows comprehensive multi-frequency detection while minimizing total processing time by avoiding the need to sequentially analyze all frequency ranges.
Data Source
AI summary
A method for detecting low-frequency oscillations, in particular subsynchronous resonances, in an electrical supply grid is provided. The grid has a line voltage with a rated line frequency. The method comprises recording first and second series of measurements each for performing a frequency analysis (FFT). The method includes performing a lower frequency analysis for the first series for a lower frequency range and forming a lower amplitude spectrum. The method includes performing an upper frequency analysis for the second series for an upper frequency range and forming an upper amplitude spectrum. The method includes testing whether a low-frequency oscillation component can be identified in the lower amplitude spectrum, and testing whether a low-frequency oscillation component can be identified in the upper amplitude spectrum, where the presence of a low-frequency oscillation is assumed when a low-frequency oscillation component is identified in at least one of the lower and upper amplitude spectra.