Study on the amplification effect of high-frequency harmonics in power cables

Power electronic devices will inevitably produce a large number of high-frequency harmonics in the operation of the power grid, which will cause the amplification of harmonics after injecting them into the power grid, especially in the process of long-distance transmission. In this paper, the equivalent circuit diagram of cable lines is established, and the transmission platform of high-frequency harmonics is built. The law of voltage amplification effect of high-frequency harmonics at the same position of different length cables and the law of voltage amplification effect of high-frequency harmonics at different positions of the same cable is analyzed theoretically and experimentally. The results show that for cables of different lengths, when the cable length is longer, the equivalent inductance and equivalent capacitance are larger, the resonant frequency of resonance is lower, and the magnification is smaller. For the same cable, before resonance occurs, with the increase of frequency, the voltage amplification on the cable is also gradually increased. After the resonant frequency is reached, the voltage amplification ratio at each position of the cable gradually decreases with the increase of the frequency. When the frequency increases to a certain extent, the voltage at the end of the cable gradually decreases, which is because the attenuation constant increases and the loss increases with the increase of the frequency. This paper has some guiding significance to the modeling of cable equivalent circuit and the amplification law of high-frequency harmonics in power cables.