| In today's social life,people can not live without electricity,the sustainable development of the economy can not be separated from the development of electricity.Entering the new stage in twenty-first Century,China's economic development began to pay attention to the new form of harmonious coexistence with the environment.Not only need to reduce the environmental pollution,but also to provide efficient and stable energy.From the environmental point of view,water power generation is much smaller than the environmental damage caused by thermal power generation,and can provide more stable electricity than other new energy sources.In addition,Yunnan is rich in hydropower resources,and because of the terrain is very suitable for the development of hydropower.Among them,the ultra high voltage transmission has the characteristics of strong conveying capacity and long distance,which has become a new direction of power development.At present,there are over the territory of Yunnan Guang Guang + 800kV ultra high voltage DC transmission project.The Northwest Yunnan UHV DC transmission project is also in full swing in the construction.In this paper,combined with the cloud wide ±800kV ultra high voltage DC transmission project,build PSCAD model.Analysis of HVDC pole grounding fault,the other pole overvoltage situation.The influence of the length of the line,the fault location and the grounding resistance on the overvoltage is studied.The overvoltage of the DC filter is also discussed.The scheme of how to reduce the over voltage is studied.In this paper,the propagation of the wave on the DC pole line is studied,and the overvoltage is analyzed by using the method of module decomposition.Then according to the converter overvoltage,simulation of AC side grounding fault and commutation valve grounding fault overvoltage.The overvoltage of the converter valve is studied when the ground fault occurs.This paper investigates the Overvoltage on the valve when the Y/Y winding is grounded.According to the energy action of the arrester,the overvoltage condition of AC filter is analyzed.Finally,the influence of the control mode of HVDC transmission system on overvoltage is studied.In this paper,the influence of the minimum current limiting value of VDCOL on overvoltage is studied,and the overvoltage caused by different faults in VDCOL is analyzed.It is concluded that when the minimum current limit value is 0.55,the overvoltage is the minimum in most faults.Based on the study of these three cases,the effect of Overvoltage on HVDC transmission system is studied.Study on the analysis of the situation and characteristics of voltage,can provide the basic data for HVDC system overvoltage for practical engineering,and for the protection of over voltage recommendations,reduce insulation construction investment. |
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