The power frequency electrical field on EHV AC transmission lines under corona discharge conditions

A method to calculate power frequency electrical field considering the charges caused by corona discharge around EHV (Extra-High Voltage) AC (Alternating Current) transmission lines is presented in this paper. The corona occurs when the electrical field intensity in the vicinity of the transmission lines exceeds the critical breakdown strength of air. To research the corona influence on the power electrical field, the charge simulation method and superposition principle are used to establish the computation model under this condition. Through the simulation, it is known that, due to the corona discharge, the electrical field is distorted, and the distribution curve periodically changes in time domain. As corona discharge enhances the power frequency electrical filed, the calculation model in the State Environmental Protection Administration standards in our country needs to be amended from the practical view.