Influence Analysis of the Metro Nstray Current on AC Power Grid Based on Surface Potential Gradient

The metro stray current can change the surface potential distribution, which will affect the grounding equipment of the power grid. In order to analyze the interference range and influence degree of metro stray current, the DC traction power supply system was equivalent to the resistance network model, so the stray current and rail potential can be calculated numerically. Based on the potential field distribution of the point current source in uniform media, by using the superposition principle, the potential distribution and gradient change of the whole line stray current at any position were realized. The research showed that the stray current is closely related to the running state of trains on the metro line. The more trains in accelerating and decelerating state, the wider the spreading range of stray current and the larger the amplitude of surface potential.