Computation Model of the Reradiation Interference Protecting Distance Between Radio Station and UHV Power Lines

A three-dimensional computation model of UHVDC has been designed, which is used to offer higher accuracy in the assessment of reradiation interference protecting distance between radio station and UHV power lines. The model is excited by vertically polarized plane wave, and then the interference of requested point is calculated. Based on the wire and surface electric field integral equations of interference from power line, the equivalent principle and the reasons for increased deviation with increasing frequency of wire model are analyzed. In order to assure the continuity of induced current on steel tower and embody the structure of angle-steel effectively, three-dimensional surface model of UHVDC steel tower with and without auxiliary angle-steel based on triangular element are presented. With the RWG base function and Galerkin´s method, Method of Moments is applied to calculate the interference of surface model from steel tower, and the results are compared with that of wire model. The results show the values drawn from wire model and surface model have the same change trend, and the error gradually increases with the increase of frequency. If 0.1 dB is selected as the allowable deviation value, the surface model should be used instead of wire model when frequency is over 16.7 MHz.