報告書番号

H02

タイトル（和文）

ガス絶縁機器の雷インパルス耐電圧レベルの合理的決定法に関する研究

タイトル（英文）

Study on Rational Determining of Lightning Impulse Withstand Voltage for Gas Insulated Apparatus

概要 （図表や脚注は「報告書全文」に掲載しております）

ガス絶縁電力機器においては，一層のコンパクト化によるコストダウンとSF6ガス使用量削減が求められている。このためには機器の試験電圧の合理的な決定手法の確立が必要である。我々は，立上り時間20nsの方形波インパルスを用いて，ガス絶縁電力機器を対象とした0.1～0.5MPaのSF6中準平等電界ギャップの絶縁破壊特性を実験的に調べた。特にこれまで未解明であった500ns以下の極短時間領域の絶縁破壊特性を明らかにするとともに放電時間遅れを定量的に示した。また，光学的観測機器を用いて放電進展様相の詳細観測も行った。これらの結果に基づき，任意の波形に対する絶縁破壊特性の定量的評価手法を提案し，その妥当性を評価した。さらには，実際のガス絶縁変電所（275kV～66kV級）の試験電圧の試算を行い，機器の合理化の可能性を評価した。本研究により，ガス絶縁機器の試験電圧低減の可能性が示され，更なる機器の合理化が可能であると考えられる。

概要 （英文）

Cost reduction and decrease in the volume of SF6 gas by downsizing are requested in gas insulation electric power apparatus. Therefore, it is necessary to establish a reasonable decision method of the test voltage of the equipment. In the sizing of gas-insulated switchgear (GIS), Lightning Impulse Withstand Voltage (LIWV) for the lightning surge becomes an important factor. As actual lightning surge waveforms have a steep front and the high frequency oscillations, it is difficult to estimate the equivalent standard lightning impulse voltage. We examined the discharge characteristics of SF6 at gas pressures of 0.1-0.5MPa under quasi-uniform field gaps using the steep-front square impulse. Moreover, the electrical discharge development phenomenon was observed in detail with an optical observation equipment. As the result, the V-t characteristics of short time region and discharge development phenomenon were clarified and discharge time lag was quantified. Based on the results using square impulse, the equal-area criterion as the V-t curve estimation method for the arbitrary waveform was proposed, and its applicability was evaluated. We found that application of the equal-area criterion for up to at least 5.4MHz oscillatory impulse intended for lightning surge and disconnector switching surge is possible. Based on these evaluation results, the lightning surges of standard substation layouts (gas insulated substation) obtained by EMTP were converted to the standard lightning impulse voltage by applying the equal-area criterion, LIWV of each nominal voltage was estimated. As a result, estimated LIWV of most cases of 500kV and 275kV substation in nominal voltage were lower than current LIWV. In all cases of less than 275kV in nominal voltage, estimated LIWV were lower than current LIWV. Therefore, the possibility of LIWV decrease of the gas-insulation equipment is shown by this research, and the possibility of further rationalization of apparatus was supposed.

報告者

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