The stability and reliability of the power frequency current measurement in the power system is an important means to ensure the stable and reliable operation of the distribution network.  Because the traditional current transformer contains an iron core, its ferromagnetic effect is easy to cause linear saturation and ferromagnetic resonance, and there are more and more problems in insulation performance, volume and bandwidth response.  Therefore, in view of the above problems, this paper designs a new type of current transformer based on PCB planar-type of air core coil for power frequency current measurement in distribution network. Firstly, the relationship between the current of the transmission wire and its surrounding magnetic induction is studied, and an air core coil sensor with an inverse series structure is proposed. The working state of the sensor is analyzed, and the appropriate integrating circuit is selected to obtain the optimal design scheme of the sensor. Secondly, the finite element simulation software is used to establish an air core coil model, and the induced voltage of a single PCB air core coil is calculated, and the anti-interference performance is simulated and analyzed. Finally, the amplitude-frequency characteristics, steady-state and dynamic response performance of the PCB air core coil are simulated.  Simulation analysis verifies that the designed PCB air core coil transformer has a wide frequency band, can effectively resist the influence of external interference magnetic field, and has good transient response and steady-state response performance. It is suitable for current measurement of transmission conductors in distribution network, and meets the intelligent and automatic requirements of current measurement of power system in the future.

Current Transformers,Non-contact Measurement,Current Measurement