Research On Analysis And Optimization Of The Electric Field Distribution Of 160kV HVDC Circuit Breaker

In recent years,the number of domestic HVDC project is getting rising,and as the key equipment of dc grid,high voltage direct current circuit breaker(HVDC CB)is getting more and more attention of the various scientific research units.But at present most of the research of dc circuit breaker is on the topology research stage,the production of dc circuit breaker is lack of experience.As a complex integrated equipment,the HVDC circuit breaker is made up of many sets of parts,and has complex potential distribution.In order to ensure the insulation of the dc circuit breaker safe and reliable,it not only needs enough air interval between different potential components,assessment of the electric field distribution is also needed.Based on the Nan'ao project “The production of 160 kV HVDC circuit breaker”,the thesis does some simulation research on the distribution of electric field of 160 kV dc circuit breaker,and put forward a reasonable optimization scheme of electric field to ensure safe and reliable dc circuit breaker insulation structure.As a switch device,dc circuit breaker has multiple operating conditions,and has a bigger size due to its high voltage level,which both make the electric field analysis of the dc circuit breaker optimization become more difficult.The thesis first gives all working conditions that dc circuit breaker may occur in the actual operation condition,then according to the duration divides the working conditions into steady state conditions and transient state conditions,and gives different criterion for two kinds of working conditions by engineering experience,which makes clear the working condition application of the subsequent simulation.In electric field calculation,the thesis analyzes both the whole model of 160 kV dc circuit breaker and the submodel of part of the dc circuit breaker,in which the whole model analysis is conducted with a relatively coarse mesh subdivision to find out the place the electric field exceeds the criterion so that submodel analysis can be conducted then.In the calculation of the whole model,because of the various parts of dc circuit breaker,the component parts should be named before the finite element model is established,to make the grid subdivision control and the load of potential easier.For the components with excess electric field in the whole model,the thesis will use submodel analysis method to optimize the electric field of the local parts,in which the working conditions that the electric field of the local parts are the worst will be adopted.Through analysis of the characteristics of the electric field distribution by submodel method,reasonable electric field optimization measures can be put forward,and the measures will be checked in the submodel analysis.In this way we can make full use of the limited computer resources,and improve the accuracy of the simulation calculation as much as possible,which can ensure the credibility of the calculation results.After the optimization by submodel method,the optimization measures put forward are checked by the whole model calculation,as well as examine the electric field distribution of the air gap in the transient state conditions.In this way,through the optimization by submodel method and check in the whole model calculation,as well as the examination of the maximum field strength and the space electric field distribution,the rationality of the electric field distribution can be fully affirmed,as a result the design result of DC circuit breaker meeting the requirements under different working conditions is put forward.