By WU Chunxin, TANG Zeyang & HE Lingling

Recently, the Institute of Electrical and Electronics Engineers (IEEE) Standards Review Committee passed an international standard on the monitoring of stray current in urban rail transit, formulated by the Hubei Electric Power Research Institute (EPRI) of State Grid Corporation.

The IEEE P2970 standard, "Guide for Synchronous Monitoring of the Magnitude and Distribution of Stray Current in Urban Rail Transit's Direct Current Traction System," is the first international standard established and issued by IEEE Vehicle Technology Association (VTS) in the State Grid.

The stray current generated by the traction system of urban rail transit is injected into the ground, which not only affects the safe and stable operation of the power supply system of rail transit, but also leads to the abnormal increase of the vibration and noise of the transformer, and even damages the transformer, affecting the safe and stable operation of the urban power grid.

To this end, Hubei EPRI took the lead in the world to put forward a method to guide cross-industry norms, to carry out synchronous monitoring of stray current of rail transit and DC bias current of power grid transformers, and launched a proposal in December 2020, which was unanimously recognized by many cross-industry and cross-professional experts of IEEE Power and Energy Association (PES) and VTS, and successfully established the project. 

The standard specifies the method of synchronous monitoring of stray current and distribution of DC traction system in urban rail transit, the principle of distribution, the technical requirements of monitoring devices and systems, and the processing of monitoring data, which can effectively guide the synchronous monitoring and correlation analysis of grid side and rail side, and provide data basis for the management of stray current in rail transit.