Since both ends of the AC transmission and output lines of the low-frequency transmission system of offshore wind power are power electronic equipment
current distortion in the process of grid failure may cause the adaptability decline of the existing protection . To solve these problems
this paper proposes a new method of multi-criterion comprehensive identification of transformer excitation inrush current based on fuzzy progress. The method synthesizes several characteristics of transformer inrush current
including the second harmonic
waveform symmetry
waveform sine and the ratio of reactive fundamental wave to active DC. By using different membership functions and combining the characteristics of each criterion
different weights are calculated. By synthesizing multiple criteria
the similarity degree between the comprehensive fuzzy set and the preset inrush current or internal fault standard fuzzy set is calculated using the progress function. At last
PSCAD is used to build the low-frequency transmission system model
and the operation state of the low-frequency transformer under different working conditions is simulated. The current data generated under different working conditions are processed and analyzed by Matlab
and the proposed identification method is verified. The results show that this method can synthesize the advantages of each criterion and realize the accurate and reliable identification of inrush current and internal fault in low-frequency offshore wind power system.
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