Rapid potential-controlled rectifier for securing the underground pipeline under electrolytic interference

In electrolytic interference circumstances such as underground pipelines in the vicinity of DC rail transportation power systems, either drainage methods or ICCP method has been widely used in order to secure the integrity of the pipelines. The drainage method is applied either by forced drainage system in which the driving voltage for draining the stray current from the pipelines is controlled by thyristors or by polarized drainage system which connects the pipeline with the railroads by diodes. In ICCP method, the phase-controlled rectifier with thyristors is in common use. Both methods, however, cannot respond to the dynamic fluctuation of the stray current. As a result, the pipe-to-soil potentials of the pipelines near railroads vary rapidly and therefore a new counter measure with dynamic response is necessary. In this paper, we introduce a new rapid potential-controlled rectifier consisting of full bridge circuits for bidirectional power output and IGBT switching device. Field test comparison with the existing forced drainage method showed the effectiveness of the developed rectifier for securing the pipelines under electrolytic interference.