A study on Electric and Magnetic field effects between EHV AC and DC Lines and its impact on substation equipment

摘要

To enhance the transmission capacity, to reduce the loss and to improve the stability of power system, it is appropriate to increase the maximum operating voltage of system. Commercial operation of 765kV AC lines are already in vogue & trial operation of 1200kV AC station are also being done for testing as well as to measure the interferences for any harmful effect/impact on human/livestock. High Voltage Direct Current (HVDC) transmission lines are also gaining a lot of momentum as it has got technical advantage over UHV AC transmission system due to reduced voltage drop particularly for long distances power transmission and eventually possibility of reduced operating cost. However, due to rapid urbanisation, one of the great difficulties or challenges being encountered in recent times is getting the right-of-way (ROW) for transmission system - the difficulties are either due to economic reasons or due to ecological reasons and in some cases both factors. Hence, it becomes inevitable to build new transmission corridors for UHV/EHV AC & HVDC in relatively close vicinity. Sometimes there may be situations wherein the existing towers will be re-designed for transmission with both UHV AC and HVDC lines While it is evident that there is an essential need to mitigate the effects of electromagnetic field interference in the new corridors, there would be challenges it may pose on existing assets like substation equipment in the proximity. This technical paper deals on the electric and magnetic field effects between AC and DC lines and their impact on adjacent substation equipment.