Audible noise levels of transmission overhead lines standard configurations EHV (Extra High Voltage) operated in the Czech Republic

摘要

The requirements for overhead lines (OHL) environmental influences are up-to-date mainly due to current settlement in former peripheral city areas where single overhead lines corridors went through in the past. However these areas are absorbed by civil buildings, shopping centres, residential areas etc nowadays. Their environment is deteriorated by low frequency electrical and magnetic field from overhead lines but also by the lines audible noise. Its levels must be controlled by calculations already in the project stage but mainly after new power constructions establishment. The deciding influence on the audible noise level in the EHV overhead lines surrounding is given primarily by surface electrical gradient level of active construction parts (especially conductor wires, clamps and armatures) in coordination with secondary factors as weather conditions and powerlines active parts pollution. The paper shows calculated and analysed audible noise levels generated by overhead lines of different configurations utilized in the Czech Republic. The surface electrical gradient influencing the line audible noise of conductor wires can be controlled by operational voltage and construction parameters, i.e. conductor wires diameter, their surface roughness, conductor wires number in the bundle, symmetrical and non-symmetrical bundle configuration, phase-to-phase distances in the 3-phase system, phase rotating on the tower, phase conductors height above the ground, mutual distance of parallel 3-phase systems on a double powerline common tower, or separate parallel powerlines distance. The analyses result in important knowledge for configuration design, operation and also for the overhead line trace choice.