The floating crane supply system usually incorporates large-capacity multiple asynchronous motors.During the starting process of these motors,simultaneous activation can result in substantial current surges.Consequently,the transformer bears a heavy current burden,potentially triggering the false overcurrent protection and leading to further industrial production losses.This paper investigates a protection scheme for transformers supplying multiple high-capacity motors.Firstly,the mechanism of the overcurrent during motor starting is analyzed by an equivalent model.Subsequently,a random scenario generating algorithm is proposed to generate a large number of scenarios for analysis.Furthermore,the Hilbert-Huang transform technique is employed to examine the time-frequency domain characteristics of both fault current and normal current,leading to improvements in the conventional overcurrent protection scheme.Finally,The effectiveness of the proposed protection scheme is validated through a realistic floating crane supply project in Hunan province.
关键词
定时限过电流保护/希尔伯特黄变换/电流瞬时频率特性/异步电动机启动/断续周期工作制
Key words
definite-time overcurrent protection/Hilbert-Huang transform/current instantaneous frequency characteristics/asynchronous motor starting/intermittent periodic duty
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