Research On Electromagnetic Influence And Protective Measures Of Uhv Ac Transmission Lines On Parallel Erected Lines

With the planning and construction of UHV transmission and transformation project,the shortage of land for line corridors and the influence of the electromagnetic environment have become two factors that must be considered in the new UHV transmission line project.It is an effective way to utilize land resources to erect new lines parallel to the established UHV AC/DC transmission lines.Therefore,during the construction of the line in the corridor,the electromagnetic coupling effect of the established UHV AC/DC operation lines on the subsequent new transmission lines must be considered,which is of great significance for protecting the safety of construction personnel.In the construction of the line parallel to UHV AC transmission line,the static induction voltage of the open circuit at both ends of the construction line is as high as several tens of kilovolts.After the line is lifted off,it is mainly grounded through the temporary grounding device of the tower.If too few temporary grounding devices are installed,the grounding device will melt.Thesis aims at the problem of induced electrical hazards encountered during the construction of the Changji-Guquan ±1100k V UHV DC transmission project.Based on the electromagnetic transient analysis software,a model of 1000 k V double-circuit UHV AC line on the same tower and the parallel construction of Changji-Guquan ±1100k V DC line is established.The hazards of electrostatic induction voltage and electromagnetic induction current faced by the 8km construction line near UHV AC line are evaluated,the related factors that affect the induction electricity are studied.At the same time,the influence of the tower grounding resistance on the electromagnetic induction current is analyzed.Taking into account the magnitude of the grounding resistance of the tower in actual construction,the grounding measures for preventing induction electricity of the 8km construction line are proposed.The distribution characteristics of induced voltage and current under different grounding schemes of the line are studied,and the influence of relevant factors on the induced voltage and current of the grounding device after tower by tower grounding of the line is analyzed.Finally,the induced voltage and current of multiple temporary grounding devices installed in long-distance lines are calculated,the change rule of the induced current after removing the grounding devices is studied.The effectiveness of installing temporary grounding devices at multiple locations on the construction line and the change rule of the induced voltage after removing the grounding devices are verified by field tests.The results show that,aiming at the removal sequence of the temporary grounding device,a scheme is proposed to retain the temporary grounding device at the first and last ends of the line and remove it from the middle of the construction line to both ends.The research results of this thesis provide a reference for the grounding scheme and grounding device removal scheme of the construction line parallel to the UHV AC transmission line.