Zero-Resistance-Branch Electrical Drainage System to Solve the Adverse Influence of Stray Current on Buried Pipelines

The buried pipeline's ground potential may be seriously shifted by the stray current leaking from the rail transit, leading to the problem of severe electrochemical corrosion on buried pipeline. For this, a zero-resistance-branch electrical drainage system is proposed to solve the adverse influence of stray current on buried pipeline just like the active power filtering technology in power systems, mainly consisting of a negative resistance compensating converter (NRCC) and a grounding electrode, which can directly drain the stray current to the soil without connecting the rail system. Moreover, the equivalent interference circuit model of stray current is established, and the corrosion rule is analyzed in detail. Furthermore, based on the NRCC, the zero-resistance active drainage control method is proposed to realize the absorption of stray current. As the optimization objective of the control method, the disturbance component of pipe-to-soil potential is regulated to be approximately 0, and the zero-resistance branch at the disturbance frequency can be realized without directly detecting the value of the stray current. Then, the stray current can be transferred to the new drainage branch to mitigate its electrochemical corrosion on buried pipelines. Finally, the experimental results verify the effectiveness of the proposed electrical drainage system.