A high-voltage optoelectronic probe is developed for measuring impulse voltage distribution along thyristor units in the HVDC converter valve.The dimension of the resistive voltage divider is optimized by means of num...A high-voltage optoelectronic probe is developed for measuring impulse voltage distribution along thyristor units in the HVDC converter valve.The dimension of the resistive voltage divider is optimized by means of numerical computation of electric field.A pulse frequency modulation(PFM) mode is adopted for the data transmission link because of its immunity to high-intensity electromagnetic interference.Experimental results indicate that the linearity deviation for the whole measuring system is within ±0.15%,and therefore it can meet requirements specified by IEC60700-1.展开更多
The reasonable conduction property is beneficial to release the deposited charges by conduction current in dielectric space charging environment,thus the level of the deep charging and the pulse discharge can effectiv...The reasonable conduction property is beneficial to release the deposited charges by conduction current in dielectric space charging environment,thus the level of the deep charging and the pulse discharge can effectively be weakened and inhibited.A traditional method for conductivity measuring under ground circumstance was used,and both the applied voltage and temperature were varied to determine the dependence of volume conductivity in PTFE modified by different filler contents.The results inferred the volume conductivity was significantly affected by the phenomenon of the percolation conduction,as well as the high-field conduction.The shallow and deep charge traps were considered to be a key factor in volume conductivity variation.In this theory,modified by inorganic semi-conductive filler,the distribution of trap density and depth in PTFE can be controlled to achieve the ideal temperature-dependent conduction property and high-field conduction property,which will finally lead to gentle release of the deposited charges while the electrostatic field reaches the conductivity-variation threshold.展开更多
文摘A high-voltage optoelectronic probe is developed for measuring impulse voltage distribution along thyristor units in the HVDC converter valve.The dimension of the resistive voltage divider is optimized by means of numerical computation of electric field.A pulse frequency modulation(PFM) mode is adopted for the data transmission link because of its immunity to high-intensity electromagnetic interference.Experimental results indicate that the linearity deviation for the whole measuring system is within ±0.15%,and therefore it can meet requirements specified by IEC60700-1.
文摘The reasonable conduction property is beneficial to release the deposited charges by conduction current in dielectric space charging environment,thus the level of the deep charging and the pulse discharge can effectively be weakened and inhibited.A traditional method for conductivity measuring under ground circumstance was used,and both the applied voltage and temperature were varied to determine the dependence of volume conductivity in PTFE modified by different filler contents.The results inferred the volume conductivity was significantly affected by the phenomenon of the percolation conduction,as well as the high-field conduction.The shallow and deep charge traps were considered to be a key factor in volume conductivity variation.In this theory,modified by inorganic semi-conductive filler,the distribution of trap density and depth in PTFE can be controlled to achieve the ideal temperature-dependent conduction property and high-field conduction property,which will finally lead to gentle release of the deposited charges while the electrostatic field reaches the conductivity-variation threshold.
