著者

鈴木 守 石井 隆裕 神尾 光一 鈴木 浩 伊庭 健二

出版者

The Institute of Electrical Engineers of Japan

雑誌

電気学会論文誌B(電力・エネルギー部門誌) (ISSN:03854213)

巻号頁・発行日

vol.112, no.10, pp.937-944, 1992-10-20 (Released:2008-12-19)

参考文献数

9

被引用文献数

3

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The idea of unbalanced load flow calculation was proposed many years ago. At that time, however, the needs for such techniques was not an urgent one. Modern power system networks are comprised of long untransposed transmission lines. Therefore, for some kinds of analysis, it is now almost impossible to treat a system as though it were a symmetrical network. The aims of most previous studies were oriented to solve voltage/current imbalance in local or small systems, as local imbalance was a serious concern. This is still an important issue, but more recently our needs have become concentrated on practical bulk power systems, since principal EHV lines are entirely untransposed. In this paper, the development of practical unbalanced load program and practical experience with it are reported. This program was developed for steady state analysis of large-scale practical networks under many possible unbalanced condition. The Newton-Raphson method in polar coordinates is used, since fast and moderate convergent characteristics are suitable for solving solutions. The program was applied to practical case studies. The models contain all of the 500 kV and most of the 275 kV overhead transmission lines in TEPCO. Since the density of the Jacobian matrix is higher than in single phase load flows, the number of non zero elements is extremely large. Convergent characteristics are excellent in all cases. The fear of numerical instability has been allayed.

著者

伊庭 健二 川崎 龍子 熊野 長次郎

出版者

一般社団法人 電気学会

雑誌

電気学会論文誌C(電子・情報・システム部門誌) (ISSN:03854221)

巻号頁・発行日

vol.114, no.2, pp.252-258, 1994-02-20 (Released:2008-12-19)

参考文献数

5

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This paper presents a method for drawing power system networks using fractal technique. It is quite common to represent power systems as visual network graph. The drawing of such graph, however, was performed manually by human-hand. Automatic drawing makes possible to represent power system flexibly. The mathematical problem seems to be similar to “How to draw planar graph”. However, unlike to the planar graph problem which treats eassentially non-separable, power systems contain a few loops. Fractal graph is utilized in this paper. Our problem is defined as follows: (1) All vertex must be on the grid. All branches must be composed of horizontal or vertical line segments. The vertex that has more than 5 degree can be divided into sub-vertices. (2) Geometrical relationship between two vertices must be preserved as long as possible (In this paper, “Geometrical” means “Directional”). (3) Branches should not cross each other as long as possible. The method is applied to some practical power system networks. Although the method has some week points for grid systems, the test results show the feasibility of the proposed method.