Kei Ohtsuka

A H/sub infinity / optimal theory-based generator control system

A generator control system is designed on the basis of H/sub infinity / control theory, and the control performance of the system is investigated. A Riccati equation approach is first introduced. How to apply this approach to designing the generator control system is then presented. The control performance of the system based on H/sub infinity / control design is studied by numerical examples and is compared with that based on linear-quadratic control design. Some advantages and disadvantages of the generator control system based on the H/sub infinity / design are clarified. >

Decentralized Control of a Multimachine Power System

Abstract A decentralized control methodology for multimachine power systems is proposed and studied. The first step is to solve the corresponding centralized control problem. The LQ1 regulator or the H∞ regulator is applied to the conrol system. One can then examine the relattive effects of the control gains and eliminate those that are small. A human judgement based on the power system engineering leads to an application of tieline power of the system to the decentralized control design. The methodology is verified by an illustrative example. This study tells us that the tieline power is served as an important variable, and is essential to mull imachine power system control. This study also suggests a possibility of a unified design for decentralized systems of both voltage and power stabilization and load frequency control.

Reviewing Japanese sake quality and its brewing by AHP

This paper investigates the brewing process and sensory evaluation of Japanese sake by using the analytic hierarchy process (AHP). Every brewer of Japanese sake has his own policy to develop many brands of sake with various kinds of sake quality, putting different sales prices on them. Every sake brewing expert establishes his own techniques of brewing each brand of sake taking into considerations the managers policies. In this paper, various estimations are given using AHP on both the primary brewing factor and primary quality factor of Japanese sake. This leads to a possibility of quantifying some brewing policies and expertise that the manager and the expert have in mind. Some new considerations on Japanese sake quality and its brewing process are thus given.

Estimation of category mixture rate for boundary area on remote sensing image due to fuzzy inference

The authors propose a fuzzy estimation method for the category mixture rate in the mixed pixel (mixel) of the satellite image. The distribution of the brightness lever for the training data is handled by a fuzzy set, and the category mixture rate in the mixel is estimated by fuzzy inference. The proposed method, therefore, takes into consideration the scattering of the training data in the membership function. The simulation result shows that the proposed method is a useful technique for estimating the category mixture rate of the mixel located on the boundary area between two different categories.<<ETX>>

On LQI regulator applied to inverse response system

Inverse response systems are characterized by a transfer function with an RHS (right-hand side) zero. It is well known from regulator theory that the response of such an RHS zero system is constrained even when controlled by an ideal LQ (linear-quadratic) regulator. It is shown in the present work that the RHS zero system has another kind of constraint on its response when controlled by a LQI regulator.<<ETX>>

An Application of the Extended Kalman Filter to Parameter Identification for Stability Analysis of Power Generating Systems

Abstract An application of the extended Kalman filter to identifying parameters used for the analysis of the power system stability is presented. The parameters are identified using the method based on the field data in a 69 MVA power plant. The results show that the reactances X d and X q of the generator and the time constants T MS and T AS governor are quite different from the design data. The identified data are well verified by digital simulations of the power system stability. It is also shown that the deviation in the reactance X q has great influence on the power stability analysis.