Estimation of voltage and Sag in Overhead Transmission Lines With Electric Field Sensor Array

A non-contact voltage measurement technology is proposed to reduce the industrial safety risk during the maintenance of high-voltage transmission and distribution lines and to improve work efficiency during the inspection. In this technology, three single-axis electric field sensors are used to design a sensing array and are placed on the ground below the measured overhead line. Moreover, these sensors are distributed at equal distances and orthogonally across the overhead line. When the geometric specification of the proposed overhead line is given as initial values, the designed voltage algorithm can accurately evaluate the voltage harmonic distortion of each phase based on the space electric fields measured by the sensor array. The difference between this study and other related non-contact voltage measurement methods is the consideration of conductor sags. Hence, the electric field around an overhead line simulated in this study is similar to the actual electric field. Moreover, the proposed electric field simulation is presented in a 3D model. Based on this 3D model, the new voltage distortion measurement algorithm can accurately measure the voltage distortion of the overhead line with sags. In order to verify the feasibility of the voltage distortion measurement algorithm, this study uses possible combinations of three overhead-line geometric variables, including: conductor radius, conductor sag, and distance between two adjacent conductors, to evaluate the accuracy of the proposed algorithm. The simulation results show that the maximum error of the proposed voltage distortion measurement method is less than 7% under the possible geometric deviation of the measured overhead line.