A New Monitoring Method for the Dynamic Stray Current Intrusion of Subways

Metro dynamic stray current invades urban power grid, which leads to DC bias hazard of transformer. In view of the shortcomings of the current dynamic stray current intrusion monitoring technology, Firstly, the fluxgate technology scheme of large-size flexible stray current sensor has been proposed. According to the principle of self-excited oscillation fluxgate circuit, an open-loop high-precision dynamic stray current sensor with a radius of 1m has been developed, and it has passed the tests without AC current interference and 50A AC current interference. Compared with the current Hall sensor and four-point stray current sensor, the new stray current sensor improves the signal conditioning circuit, which can effectively improve the sampling resolution of stray current to 10Hz and meet the requirements of dynamic tracking of stray current. Finally, the effectiveness of this method has been proved by different tests and application cases, and the next improvement direction has been pointed out, which provides new technical support for stray current monitoring.