A new method for current measurement of overhead lines

With the rise of the power transmission capacity and the voltage classes, traditional current transformers begin to reveal more and more problems. In view of this, a novel approach is presented in this paper to measure line currents by using the magnetic field under overhead lines. The characteristics of the magnetic field around overhead lines are analyzed in detail, a method for measuring horizontal magnetic field is proposed, and the formulas for calculating three-phase line currents are deduced according to the horizontal magnetic field at three different places under overhead lines. Finally the magnetic fields under transmission lines are simulated both in steady and lighting states with Maxwell software and the line currents are calculated by adopting the proposed method. The feasibility of the proposed method is verified through comparison between the calculated value and the simulation value.