Simulation of broadband non-contact current transformer and harmonic-transient effect in power system

In the “double-high” power system (high proportion of renewable energy and high proportion of power electronic equipment), the broadband harmonic and high-frequency transient oscillation problems are prominent due to the high proportion of new energy grid-connected and power electronic equipment access, and the traditional current transformer is difficult to meet the accurate measurement requirements due to the limited frequency band. In this paper, the working principle and performance differences of six non-contact current transformers are systematically analyzed, and the influence of harmonic and high-frequency transient signals on the power system is studied by Simulink simulation experiments. The experimental results show that the Roche coil can accurately capture the high-frequency transient signal at the MHz level, but the error is significant in the low-frequency band. Electronic current transformers perform well in harmonic separation and fundamental wave reduction, but the high-frequency response is limited by the bandwidth of electronic devices. The increase of harmonic amplitude will lead to an increase in fundamental wave distortion rate, and the high-frequency transient signal can reduce the effective value of the fundamental wave by about 15%, threatening the stability of the power grid. The research results provide a theoretical basis for the selection and optimization of broadband sensors in the “double height” system, and it is suggested to improve the measurement accuracy by combining multi-sensor fusion and digital algorithms, to provide technical support for the safe operation of the power grid.