Experimental Research On Corona Current Of HVAC And HVDC Transmission Lines In Parallel

Due to the rapid growth of power demand and the uneven distribution of geographical resources, long-distance and large-capability transmission becomes an important part of electric power system. At the same time, the increasingly shortage of transmission corridor makes AC and DC parallel transmission system become indispensable.With the increasing use of extra-high voltage(EHV) and ultra-high voltage(UHV) transmission lines, the electromagnetic environmental problems caused by corona discharge are becoming more and more serious. Corona current caused by corona discharge would generate the electric field, magnetic field, radio interference and audible noise, which may affect people’s work and life. What’s more, in the system of AC and DC parallel transmission, the parallel transmission lines will interact, which leads to the change of space electric field. The surrounding environment needs to be reappraised.In this paper, firstly, according to the measurement of HV test line, a corona current measurement system is developed for the investigation of HV test line. The measurement principle and system configuration are described. Thanks to the photovoltaic technology and computer control technology, problems such as high-voltage insulation, interference suppression, high-frequency signal sampling, and signal record and transmission etc. are solved. Secondly, performance tests of the measurement system are processed. On one hand, experimental platforms are set up in electromagnetic compatibility(EMC) Lab in order to test the electrostatic discharge immunity and RF electromagnetic field immunity. On the other hand, a few experiments are done to verify the equivalence of measurements at high-potential side and low potential side. At last, the experimental platform of AC/DC hybrid transmission lines is set up and a number of experiments are accomplished. The measurement system is used to measure corona currents. The wave forms, currents and energies are being calculated and analyzed to obtain the change rules of the corona currents when DC and AC lines are parallel.The research provides a reliable basis for further study on corona discharge of AC/DC hybrid transmission lines.