Analysis Of Ecological Environment For 500kV Four Circuits Power Transmission Lines On Same Tower

Multi-circuit transmission line (MCTL) on same tower is one of the popular over-head transmission line technologies both in China and overseas, which has good economic benefit and application value. Comparing to a single-circuit, the electromagnetic field intensity around the MCTL transmission line on same tower is greatly increased which will influence ecological environment consequently; therefore, the electric field intensity and magnetic field intensity of MCTL on same tower will directly influence its application. The paper analyzes this problem from both principle and practice side.The paper firstly introduces the electromagnetic field calculation method of transmission line. Considering the deficiency of the traditional equivalence charge method (ECM) for analyzing extra -high transmission line, it proposes two dimensional finite element method (FEM) model of its electromagnetic field secondly. Due to this is an open domain, it introduces a solution for such kind of boundary condition, via comparison with testing data, it is testified that the proposed method is feasible.The transmission line electromagnetic field is among extremely-low frequency (ELF) electromagnetic field; so it has close relation with human health and ecological environment. This paper discusses the ELF ecological effect and its influence to ecological environment as well as human health; moreover, we investigate its evaluation criteria.At present, the 500kV four circuits transmission line (FCTL) on same tower has been widely used overseas and China is also plotting its own project. As an example, the paper considers it is feasible from the view of ecological environment. The paper also develops a special program to calculate the electric field and magnetic field of the selected tower modes and phase sequences, and concludes the suitable tower modes and phase sequences which meet ecological environment criteria. The proposed method and the analysis results in this paper will contribute to transmission line plan.