Modeling and Error Characteristic Analysis of Current Transformer Considering Low-Frequency Condition

The operation performance of current transformer (CT) at low-frequency is directly related to the accuracy of electric energy measurement in low-frequency transmission process. In this paper, the error characteristics of low-frequency electromagnetic CT are studied and analyzed based on theoretical model and finite element simulation. Firstly, the mathematical model of CT error is established, and the parameters affecting the ratio error and phase error are analyzed. Then, the finite element modeling of low-frequency CT is carried out. On this basis, the influence of different working conditions represented by frequency, secondary load and power factor, as well as different structural parameters represented by core cross-sectional area and inner diameter on the error characteristics of low-frequency CT is simulated and analyzed. Finally, the simulation results are compared with the mathematical model to verify the correctness of the mathematical model and the analysis conclusion. The results show that the change of structural parameters and working conditions will have a serious impact on the error characteristics of low-frequency CT, which should be paid more attention to in the process of optimization design and operation.