Research on the EMI mechanism and suppressing measures of TEV disturbing the electronic transformer

摘要

Repetitive ignitions of SF₆ gas discharge during switching operation in GIS may result in transient enclosure voltage (TEV) phenomena with the characteristics of high steepness, high amplitude and high frequency, which will disturb the electronic transformer seriously and decrease the reliability of electronic transformer dramatically. For this reason, the research about EMI mechanism of TEV which disturbs the electronic transformer is carried out in this paper. To study the EMI mechanism, ECVT is taken as the electronic transformer sample and a novel SF₆ gas discharge reignition model is established to calculate TEV. Furthermore, the secondary voltage of ECVT U₂ under the action of TEV, which may directly destroy the collection power module of electronic transformer is calculated as well. Moreover, factors as ground inductance, ground resistance and the capacitance of voltage divider which influence on the U₂ are discussed. The results reveal that increasing the ground resistance or in a certain range increasing the grounding inductance may decrease the amplitude of U₂. But for the capacitance of voltage divider, the value range is very important. In this study, the secondary voltage of ECVT U₂ decreases with the increasing of capacitance if the capacitance value is larger than 10pF. While, U₂ may drop off dramatically to a very small value with the decreasing of capacitance if the capacitance is smaller than 1pF. Although reducing the capacitance of the voltage divider is regard as an effective way to suppress the TEV which disturbs the electronic transformer, it can't be realized in practice. Therefore, a conclusion can be drawn that at present increasing, the ground resistance and inductance in a definite range is a practical and realizable method.