Development of a Stray Current Testing Device Based on Harmonic Current Source Technology

The stray current of rail transit system will cause the harm of DC bias of transformers in urban power grid. Under the action of dynamic stray current, the transformer presents complex DC bias characteristics, which can only be studied by means of experiments at present. Transformer bias test under dynamic measured stray current waveform must be carried out with the help of professional power supply platform, and there is no suitable power source hardware to assist this test. In order to simulate the dynamic stray current of rail transit system, a design scheme of stray current test power supply based on harmonic technology has been proposed and a prototype is developed. Firstly, the requirements of stray current test power supply have been analyzed, and the design scheme of stray current test power supply has been proposed. The basic hardware structure of the test power supply and the specific performance requirements of the related modules are introduced in detail. On the basis of developing and processing the prototype, the stray current data measured on the spot is used as the input of the prototype, and a 10kV single-phase transformer is used as the load of the output of the power supply. The validity of the design principle and hardware scheme has been preliminarily verified by testing. The technical scheme of power supply proposed in this paper can be used as a reference for the test of transformer magnetic bias caused by stray current.