Study on Electromagnetic Environment of Multi-circuit Transmission Lines on Same Tower

The technology of extra-high voltage multi-circuit transmission lines on same tower is one novel transmitting technology, which can obviously decrease the route way resource, and the transmission capacity per area is increased prominently. But its electromagnetic environment problem is one of the keys which affect the feasibility of EHV transmission lines, so it's important to study the electromagnetic environment. This paper calculates the electric field intensity and magnetic field intensity generated by transmission lines in different phase line sequences of different tower modes. We can accurately obtain the electric field and magnetic field distribution under EHV transmission lines using finite element analysis. From these simulating results, we can get the most reasonable position of transmission lines on tower and the best phase line sequence which has the least electromagnetic field intensity in 500 kV/220 kV mixed voltage four-circuit transmission lines on same tower. This can provide theoretic reference for construction of transmission lines.