ĐÁNH GIÁ CÁC PHƯƠNG PHÁP TÍNH TOÁN TỔNG TRỞ SÓNG ĐƯỜNG DÂY TẢI TRÊN KHÔNG

Abstract

Currently, method for determining the surge impedance of overhead transmission line the soil is considered to be absolutely conductive, the soil resistivity is
considered to be zero, only of the parameter of the height of the conductor above the ground is considered and size of wire. This method is only valid in the case of
steady mode, the transmission line is only excited by working current. In the case of lightning current, this calculation method will cause very large errors, leading to
the calculation results of overvoltage on the transmission line being no longer accurate. Using the surge impedance method combined with the electromagnetic
transient program to simulate is one of the modern methods. This paper uses the wave propagation direction to determine surge impedance of the transmission line.
In addition, the authors also review methods for determining the surge impedance of overhead transmission line when considering the influence of ground current
return as well as frequency of lightning current. The results of calculating the total wave impedance of overhead transmission lines from previous publications are
compared with the method proposed by the authors. The article uses the electromagnetic transient simulation program EMTP/ATP to simulate and calculate.