摘要
A trend identification and early warning method for steady-state power quality(PQ) based on the trend-span index is proposed, aiming at the limitation of the traditional steady-state PQ classification warning, which mostly focuses on the comparison between the numerical value and the threshold and seldom considers the long-term change trend of the indices. Firstly, the STL decomposition algorithm is used to decompose the steady-state PQ index time series to extract the trend components. Secondly, the Mann-Kendall method is used to identify the trend type of the trend components of the PQ index. Thirdly, the trend-span index is proposed to quantify the trend change of the PQ index and the early warning level is divided according to the distribution characteristics of the trend-span indices. Finally, the ideal solution sorting method is used to comprehensively evaluate the risks of the PQ deterioration at the monitoring sites. The method is applied to the actual monitoring data of the steady-state PQ in a city. The trend warning of various PQ indices and the overall power quality level of monitoring sites is carried out. ? 2023 Power System Technology Press.
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