著者
林 泰弘 松木 純也 鈴木 良治 武藤 英司
出版者
The Institute of Electrical Engineers of Japan
雑誌
電気学会論文誌. B (ISSN:03854213)
巻号頁・発行日
vol.125, no.9, pp.846-854, 2005
被引用文献数
34 17

Sending voltage profile of distribution feeder is controlled by changing a tap of distribution transformer. In a distribution network with distributed generators, for reasons of effect of reversed flows from them and existence of a great number of sending voltage profile candidates, it is not easy to control sending voltage profile within the acceptable voltage limit. In this paper, in order to determine the optimal sending voltage profile of distribution transformer in a distribution network with distributed generators, the authors propose a new method to determine the optimal sending voltage profile so as to minimize total number of tap position's change per day under constraints of acceptable voltage limit. In the proposed method, after calculating acceptable range of three phase voltage of distribution feeder, the optimal profile of tap position within the calculated acceptable voltage range is determined among these candidates by using reduced ordered binary decision diagram (ROBDD) which is an efficient enumeration algorithm. In order to check the validity of the proposed method, numerical simulations are carried out for a distribution network model with a distributed generator.
著者
織田 慎一郎 見目 喜重 中川 重康 榊原 建樹
出版者
一般社団法人 電気学会
雑誌
電気学会論文誌. B (ISSN:03854213)
巻号頁・発行日
vol.117, no.8, pp.1146-1151, 1997
被引用文献数
1

So far a single-stage neural network has been proposed to forecast insolation of next day. In the present paper, a multi-stage neural network is developed to reduce forecasting error further. A first-stage neural network forecasts average atmospheric pressure of next day from atmospheric pressure data of previous day. A second-stage neural network forecasts insolation level of next day from the average atmospheric pressure and weather data of previous day. A third-stage neural network forecasts insolation of next day form the insolation level and weather data of previous day. Meteorological data of Omaezaki, Shizuoka at April 1994 are chosen as input data. The insolation values forecasted by the multi-stage and the single-stage neural networks are compared with the measurement ones. The results show that the forecasting error is reduced to 24% (by the multi-stage) from 33% (by the single-stage).
著者
久保川 淳司 佐々木 博司 大久保 嘉人 餘利野 直人 横山 隆一 田辺 隆也
出版者
一般社団法人 電気学会
雑誌
電気学会論文誌. B (ISSN:03854213)
巻号頁・発行日
vol.113, no.2, pp.138-144, 1993

In modern industrialized societies, it is mandatory to supply uninterruptedly high quality electric energy with modest cost while preserving better environments. This can only be realized through very sophisticated power system operations that compromise several contradictory factors stemming from economy, security and environment. Since these factors are in trade-off relationships to each other, they should be treated as such. A class of problems that simultaneously satisfy several criteria in trade-off relationships are called &ldquo;multi-objective optimization problems&rdquo;. Optimal power flow (OPF) has been regarded as the most powerful means to obtain such system operation plans, it only optimizes a single objective function.<br>This paper proposes an efficient solution methodology for a class of multi-objective optimal power flow problems which makes use of a heuristic search method. An optimal solution can be found in the proposed heuristic search method based on local information on a preference index which is arbitrarily chosen out of a given set of objectives. This circumvents the exhaustive evaluation of all non-inferior solutions which is needed in the existing multi-objective OPF algorithm proposed by the authors, thus dramatically reducing the solution time. The proposed method has been coded and applied to the IEEE 57 node test system. Simulation results have demonstrated the possibility of utilizing this method in on-line environments.
著者
久保川 淳司 大久保 嘉人 佐々木 博司 横山 隆一
出版者
一般社団法人 電気学会
雑誌
電気学会論文誌. B (ISSN:03854213)
巻号頁・発行日
vol.118, no.3, pp.239-245, 1998

As the necessity of high quality electric power supply is increasing, it has been required to make up sophisticated power system operations in which several requirements stemming from economy, security and environmental aspects should simultaneously be satisfied. In general, a problem of satisfying several noncommensurable criteria is called a multi-objec-tive optimization problem. Although the most powerful means to obtain desirable system operations is optimal power flow (OPF), a straightforward application of the conventional OPF optimize only one objective and the remaining objectives must be treated as constraints. However, since such objectives are in trade-off relationships each other, it is necessary to develop an efficient multi-objective OPF.<br> In this paper, we shall propose a solution method of multi-objective OPF by means of fuzzy coordination. In the first step, the degree of satisfaction of Decision Maker on each objective would be maximized with a pre-specified member-ship function. The membership function would be updated in accordance with the DM's preference information and target value of the objective function. The degree of satisfaction will be improved step by step by updating the membership functions. Finally, the saticificing solution for the Decision Maker would be obtained. The proposed method has been applied to the IEEE 57 and 118 test system, producing successful results.
著者
黄 〓 塚尾 茂之 田村 康男 岩本 伸一
出版者
一般社団法人 電気学会
雑誌
電気学会論文誌. B (ISSN:03854213)
巻号頁・発行日
vol.114, no.12, pp.1288-1294, 1994
被引用文献数
1

With rapid growth of the number of literatures on nonlinear systems, nonlinearities existing in the systems under study have drawn much attention. Studies on the effects of nonlinearities in power systems have been becoming an increasingly important part of researches for the investigation of system stability. It is probable that hidden phenomena may unexpectedly emerge due tc the nonlinearities that are involved in load flow equations, generator swing equations and characteristics of control equipments and loads, etc.<br> This paper presents a new Catastrophe Theory application to nonlinear power systems. Making use of the concept of Duffing's equation, we show that a Catastrophe Theory analogy can be used to interpret unstable phenomena caused by system nonlinearities from the viewpoint of oscillations. When considering the system nonlinearities, due to ill-combination of system parameters and periodic disturbances, there may exist the characteristic &ldquo;jumps&rdquo; in system states corresponding to slow (quasi-dynamic) changes of the frequencies of periodic disturbances. With this Catastrophe Theory approach, a system bifur-cation set can be identified to assess the unstable phenomena of power systems.
著者
兎束 哲夫 池戸 昭治 上田 啓二 持永 芳文 船橋 眞男 井手 浩一
出版者
The Institute of Electrical Engineers of Japan
雑誌
電気学会論文誌. B (ISSN:03854213)
巻号頁・発行日
vol.125, no.9, pp.885-892, 2005
被引用文献数
8 7

In AC electric Railway, three-phase voltage is changed into the single-phase circuit of two circuits with the Scott-connected transformer. If it becomes large unbalancing of the load between single-phase circuits, voltage fluctuation becomes large on three-phase side. Then, Railway Static Power Conditioner (RPC) was developed for the purpose of controlling voltage fluctuation on three-phase side. An RPC is comprised of a pair of self-commutated PWM inverters. These inverters connect the main phase and teaser feeding buses, coupled with a DC side capacitor such as a Back-To-Back (BTB) converter. In this way, the two self-commutated inverters can act as a static var compensator (SVC) to compensate for the reactive power and as an active power accommodator from one feeding bus to another.<br>20MVA/60kV RPCs started commercial operation in 2002 at each two substations on the newly extended Tohoku Shinkansen for compensating voltage fluctuation on three-phase side caused by traction loads, absorbing harmonic current. The results of operational testing indicate that an RPC can accommodate single-phase loads such as those of PWM-controlled Shinkansen and thyristor phase-controlled Shinkansen, and handle the exciting rush current of transformers, as well as compensate for harmonics successfully.
著者
道上 勉 鬼塚 長徳 北村 哲
出版者
一般社団法人 電気学会
雑誌
電気学会論文誌. B (ISSN:03854213)
巻号頁・発行日
vol.110, no.11, pp.887-894, 1990
被引用文献数
1

The previous generator excitation control system is based on AVR control of generator terminal voltage. This system can't accommodate reactive power up to the facility limit even when the power system voltage decreases to the limit for stable operation. We attempted to develop advanced excitation control system (PSVR) to achieve higher constant sending end voltage of power station. We intended to apply the system to the generator connected to a 500kV system which contributes most effectively to the voltage stability of a bulk power transmission system. This PSVR produces higher control gains than the AVR, the following functions were adopted: (1) AVR gain reduction circuit, (2) phase compensation circuit, and (3) damping improvement by enlarging the limiter of the PSS. In addition, various functions were provided. These include voltage slope characteristics to balance the reactive power of adjacent generators and PSVR output and terminal voltage limiter to stabilize the generator operation. Previously to an application to a real system, a transient response test was performed by combining PSVR and generator simulator to verify the damping improvement and stability of the voltage control.