The invention provides a method for measuring the
direct current magnetic bias current of a neutral point multi-point grounding power
transformer, which comprises the following steps of: 1,
cutting sampling flat steel with the same length from each grounding flat steel as a sampling
resistor, and applying a
current source to two ends of one of the sampling flat steel; 2, connecting voltmeters to two ends of the
cut length of each sampling flat steel, and sampling
voltage signals of the sampling flat steel; and 3, enabling the
current source to apply currents of different magnitudes twice, enabling each piece of sampling flat steel to respectively extract
voltage signals under the working condition of the currents twice, obtaining the actual resistance value of the sampling
resistor through conversion under the condition of considering the inherent grounding current of the neutral point through the known current and
voltage signals, and then measuring a direct-current magnetic bias current
signal flowing through each piece of flat steel. The method can accurately measure the direct-current magnetic bias current of the neutral point of the power
transformer when multiple grounding flat steel is grounded, is suitable for
field detection and on-line monitoring, and has the advantages of being free of temperature drift and capable of being calibrated on line compared with a traditional Hall sensor.