The Development Of Rogowski Coil Current Transformer

With the development of power system, on one hand, the capacity of the power system is increasing very rapidly and the system current becomes larger and larger, so it becomes very difficult for a traditional current transformer (CT) to undertake the measurement task . On the other hand, with the optimization of the administration and allocation of the power energy, it is very urgent to develop a new type of CT to meet such requirement.According to the actuality of the present research on CT, we bring forward a new design scheme based on the Rogowski coil, In this design, the protection in short circuit failure and the measurement in normal condition are both fulfilled. It can also communicate with the computer through the communicating interface, sending the parameter of the system current and accepting the instruction.In this paper, the factor that influence the precision of measurement is analyzed. Error related to the model establishing and screen cover is studied in both theoretical and experimental way. According to the causation of the error, the adjustment part is adopted in the processing of signal. In addition, the characteristics between amplitude and frequency are also analyzed.In order to fulfill the protection more effectively in the short circuit failure, a new method based on the varying rate of the system current is developed.In order to get the virtual value of the system current, considering the characteristic of the Rogowski coil output, a new integral method based on software is adopted and the traditional integrator is omitted. By this method, the precision of the measurement is improved.In this paper, both the hardware and the software are designed according to the demand of the system. At last, the CT developed in this paper worked well through the experimental test.