Analysis on transfer characteristics of Rogowski coil transducer to travelling wave

The electronic current transducers based on Rogowski coil are now widely used in digital (smart) substations. But the high frequency response feature of Rogowski coil has not been fully developed, which results in a fact that travelling wave fault location technique can´t be applied in digital substations yet. To improve this situation, this paper introduces Rogowski coil´s transfer principle and structure features, studies two types of coil model - lumped parameter and distributed parameter, and then design a set of suitable coil parameters for travelling wave transfer. According to the coil´s parameters, transient responses of two models are compared by computer simulations. To truly restore original traveling wave signals, a novel compound integration circuit is developed, which consists of an active integrator and a passive RC integrator. The active integrator works within low-frequency band, and the passive one works within high-frequency band. Finally, the frequency response characteristic of complete circuit containing both Rogowski coil and the compound integrator are obtained, which could show the transfer ability to travelling wave.