Research on the pulsed flashover characteristics of vacuum insulation material is significant for the design and manufacture of pulse power devices. In view of the voltage increase rate of the fast pulse （pulse steep...Research on the pulsed flashover characteristics of vacuum insulation material is significant for the design and manufacture of pulse power devices. In view of the voltage increase rate of the fast pulse （pulse steepness）, the vacuum fiashover characteristics of pure epoxy under different steepnesses is investigated by using a pulse generator with parameters of a rise time of 40 ns and a full width at half maximum of 2.5 μs. Pulses with six levels of steepness were achieved by changing the charging voltage of the generator. Based on the linear equation and electron emission equation, the relationship between the flashover voltage and pulse steepness was fitted. By virtue of the fitted formula, it was possible to predict the flashover voltage under near DC or higher steepness conditions. Based on the electron emission equation, the relationship between the time delay and flashover field was also fitted. Result shows that F-N electron emission dominates the flashover process.展开更多
Transformers are widely distributed and extremely important energy conversion equipment in the power system.However,the high altitude electromagnetic pulse(HEMP)can induce a steep pulse voltage with a peak value of up...Transformers are widely distributed and extremely important energy conversion equipment in the power system.However,the high altitude electromagnetic pulse(HEMP)can induce a steep pulse voltage with a peak value of up to thousands of kilovolts on the overhead line,and the frequency is up to 100 MHz,which is easy to damage the transformer and seriously threaten the safe and stable operation of the power system.Therefore,to protect the safety of the power system,analysing the transformer wave process under the action of HEMP is necessary.Accordingly,there is a need for an ultrawide band model of the transformer.In this paper,the skin effect of winding is analysed,the dielectric response of oil-paper is fitted with the double relaxation Cole-Cole model,and the frequency dependent models of distribution parameters are established.Fractional order terms are introduced into the traditional multi-conductor transmission line(MTL)integer order model to describe the characteristics of these distribution parameters so that the frequency application range of the MTL model is extended to 100 MHz.The proposed MTL model is solved by the finite-difference time-domain algorithm and verified by the finite element method and experiment.The error is less than 5%,which verifies its accuracy and effectiveness.展开更多
基金supported by National Natural Science Foundation of China(No.50437030)
文摘Research on the pulsed flashover characteristics of vacuum insulation material is significant for the design and manufacture of pulse power devices. In view of the voltage increase rate of the fast pulse （pulse steepness）, the vacuum fiashover characteristics of pure epoxy under different steepnesses is investigated by using a pulse generator with parameters of a rise time of 40 ns and a full width at half maximum of 2.5 μs. Pulses with six levels of steepness were achieved by changing the charging voltage of the generator. Based on the linear equation and electron emission equation, the relationship between the flashover voltage and pulse steepness was fitted. By virtue of the fitted formula, it was possible to predict the flashover voltage under near DC or higher steepness conditions. Based on the electron emission equation, the relationship between the time delay and flashover field was also fitted. Result shows that F-N electron emission dominates the flashover process.
基金Energy Security Technology Project of Huaneng Group Headquarters Science and Technology Project,Grant/Award Number:HNKJ20-H87。
文摘Transformers are widely distributed and extremely important energy conversion equipment in the power system.However,the high altitude electromagnetic pulse(HEMP)can induce a steep pulse voltage with a peak value of up to thousands of kilovolts on the overhead line,and the frequency is up to 100 MHz,which is easy to damage the transformer and seriously threaten the safe and stable operation of the power system.Therefore,to protect the safety of the power system,analysing the transformer wave process under the action of HEMP is necessary.Accordingly,there is a need for an ultrawide band model of the transformer.In this paper,the skin effect of winding is analysed,the dielectric response of oil-paper is fitted with the double relaxation Cole-Cole model,and the frequency dependent models of distribution parameters are established.Fractional order terms are introduced into the traditional multi-conductor transmission line(MTL)integer order model to describe the characteristics of these distribution parameters so that the frequency application range of the MTL model is extended to 100 MHz.The proposed MTL model is solved by the finite-difference time-domain algorithm and verified by the finite element method and experiment.The error is less than 5%,which verifies its accuracy and effectiveness.
