| The construction of UHV transmission project has always been the focus of research on energy field at home and abroad.China's first UHVDC project Yunnan-Guangzhou line(Yunnan-Guangdong ±800kV UHVDC transmission line)Many aspects of high voltage transmission engineering have significant advantages.Has an irreplaceable advantage in terms of long-distance capacity and in response to the increasingly tense transmission corridors and the growing air pollution.The future of China is to "thirteen five" during the completion of"four cross six straight" 10 projects,not only that,the future will have more special high-voltage projects will be put into operation,which reflects the UHV transmission in advanced,Reliability,economy and environmental friendliness.±800kV UHVDC transmission project is the world's highest power grid in the operation of the highest level,and the future ±800kV will also be the most important DC transmission voltage level.So the impact of UHVDC over-voltage and over-voltage measures to conduct in-depth study of the future construction of UHV projects can provide reference and advice.In this paper,PSCAD/EMTDC is been selected,which is the most commonly used electromagnetic transient simulation software at home and abroad,as simulation tool.The simulation model is based on the operating parameters of the YunGuang ±800kV UHVDC project.The Yunnan-Guangzhou line is also the first UHVDC transmission project in the world which has been put into commercial operation and won the national high quality engineering gold award.And reference value.In this paper,for the symmetrical splitting,asymmetric splitting and non-indentation arrangement of the flat-wave reactor,the high-side Y/Y converter valve side,the double 12-pulse commutation unit intermediate bus voltage,the valve top voltage,The upper group of 12 pulsating commutation unit middle bus voltage,four points at the voltage of the simulation comparison,and from the economic and technical aspects of the choice of flat wave reactor split layout.In this paper,the AC side of the single-phase and three-phase ground fault,rectifier and inverter side of the AC filter C1,the valve valve top,the DC line import and export lines and the midpoint of the above points of the voltage,the simulation analysis is carried out,and the more serious overvoltage phenomena are analyzed theoretically.And then the DC lines are divided into several segments,and each node were ground short circuit experiments,simulation of non-fault pole of the voltage waveform,found near the midpoint of the failure,the perfect pole of the over-voltage situation is the most serious And the mechanism of overvoltage generation is theoretically expounded in combination with traveling wave theory.Finally,this paper describes the factors that affect the level of over-voltage,and proposed to limit the level of over-voltage measures. |
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