Correlation Analysis of Direct Current of the Transformer Neutral Point and Rail Transit

In this paper, online monitoring devices for DC current, noise, and vibration have been installed. Correlation analysis of direct current of the transformer neutral point and rail transit has been carried out. Results show that the neutral point DC current on the 220kV side of the #1 and #2 transformers is closely related to the operating times of the rail transit system. There is no correlation between the neutral point DC current and the main transformer load. During the subway operating periods, the noise from the #1 transformer fluctuates significantly and increases abnormally, with the maximum noise reaching 83.1 dB. The vibration of the #1 transformer is closely related to the subway operating times. During the subway operating periods, the dominant frequency of vibration at measurement point 1 of the #1 transformer is 350 Hz, whereas after the subway stops, the dominant frequency shifts to 100 Hz.