Analysis on natural main frequency

After the fault of EHV or UHV transmission line, natural main frequency makes the difference with the changing of fault place. The paper analyzes expression of the natural main frequency approximately at the difference fault places. The conclusion is that the nearer the distance of the fault place, the higher the natural main frequency and the farther the distance of the fault place, the lower the natural main frequency. In addition, the natural main frequency is in a range and the natural main frequency is finite. The accuracy of changing curve and the range of the natural main frequency have been proven by PSCAD procedure in a practical UHV transmission line.