Radio interference characteristics of UHVAC test lines and prediction for long lines

In order to accurately evaluate the radio interference (RI) level generated by ultra-high voltage alternating current (UHV AC) power lines, we theoretically analyzed multi-conductor test line using the modal analysis method. The RI field strength distribution characteristics under test lines were deduced when the line terminals were connected to three different typical impedance networks, respectively. Then we measured the standing wave when both line ends were opened. Moreover, on the basis of the test line arrangement in UHV AC Test Base in Wuhan and the RI characteristics of short test lines, we obtained the excitation function value using the mathematical inversion from the measured RI at 0.5 MHz under the condition of heavy rain. Then we applied the excitation function value to predict and analyze the RI distributions of Jindongnan-Nanyang-Jingmen 1000 kV transmission lines, and compared the results with measured data. The results show that the excitation value of 8×LGJ-500/35 line with applied voltage of 1050 kV is 39.3 dB, and when the measurement point is less than 60 meters far from the center phase of bundle conductors, the difference between the predicted excitation function values and the measured RI values is less than 2 dB. This proves the feasibility of using the mathematical inversion to calculate excitation function values for short test lines. ©, 2014, Science Press. All right reserved.