報告書番号

T03025

タイトル（和文）

有限積分法を用いた三次元過渡電磁界基本解析コードの開発－過渡接地抵抗解析への適用－

タイトル（英文）

Development of Prototype Code for Three-Dimensional Electromagnetic Field Analysis Based on Finite Integration Technique- Appication to Transient Analysis of Resistance for Grounding Systems -

概要 （図表や脚注は「報告書全文」に掲載しております）

この論文は電力設備の接地系について有限積分法を基本とした不等間隔格子を用いた電磁界解析コードで行った三次元過渡電磁界解析の結果を述べるものである。三次元過渡電磁界の分野において，一般的な有限差分時間領域法(FDTD法)はMaxwell方程式の微分形式を用い，FDTD法の格子は直交格子に制限される。一方，有限積分法(FI法)はFDTD法と異なり，Maxwell方程式の積分形式を用いる。そのため，FITは直交格子だけでなく三角柱や構造化された非直交格子も使用できる。この論文では，FITを基礎として不等間隔の直交格子を用いた基本解析コードを種々の導体配置に適用した。主な解析結果は以下の通りである。(1)水平導体の種々の高さと半径のサージインピーダンスを計算した。計算結果とサージインピーダンスの測定値は良く一致する。(2)500kV～1000kV送電線の鉄塔基礎の地表面電界分布を計算した。電界がほとんど定常状態とみなせる時刻において静電界計算法の三角形表面電荷法による電界と比較した。広い計算領域のFITの結果と三角形表面電荷法による静電界分布はよく一致する。(3)鉄塔深礎基礎モデルとしての直方体電極について過渡接地抵抗を計算し，測定値と比較した。計算結果と実測結果はよく一致する。(4)送電線鉄塔の深礎基礎モデルで種々の大地抵抗率と深礎基礎モデルの長さについて過渡接地抵抗を計算し，それらが深礎基礎モデルの過渡接地抵抗に及ぼす影響を示した。

概要 （英文）

This paper describes three-dimensional transient electromagnetic analysis, performed by electromagnetic analysis code using nonuniform grids based on the Finite Integration Technique (FIT), for transient behavior in the grounding systems of electrical power apparatus. In general, the Finite Difference Time Domain method (FDTD) discretizes the differential forms of the Maxwell Equations of electromagnetic fields, and grids of the FDTD are restricted to three-dimensional Cartesian grids. On the other hand, the FIT discretizes the integral forms of the Maxwell Equations. Therefore, the FIT can use not only three-dimensional Cartesian meshes, but also a variety of generalized grid types such as triangular prisms and structured non-orthogonal grids. In this paper, an analysis code based on the FIT using nonuniform grids was applied to various conductor arrangements. The results of the analysis are as follows.(1) The surge impedances for various heights and radii of horizontal conductor were computed and compared with the measured results. The computed results coincide well with the measured surge impedance.(2) The electric field profiles on the ground with respect to the foot of transmission towers for 500kV - 1,000kV transmission lines were computed. The profiles were compared with static electric fields calculated by the triangular surface charge method mainly when the electric fields are stationary. The results of the FIT in the large computational domain coincide well with the electric static fields obtained by the triangular surface charge method.(3) The transient grounding resistances of a rectangular parallel piped electrode were computed and compared with measured results. The computed results and measured results were found to be in good agreement.(4) The transient grounding resistances at the foot model of transmission towers were computed for various conductivities of the ground and depths of the foot model, and their influence on the transient grounding resistances of the foot model was shown.

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