デンリョク ケイトウ ノ アンテイド カイセキ ト アンテイカ セイギョ

京都大学0048新制・論文博士工学博士乙第4054号論工博第1243号新制||工||462(附属図書館)UT51-55-G51(主査)教授 林 宗明, 教授 上之園 親佐, 教授 木嶋 昭学位規則第5条第2項該当Kyoto UniversityDFA

Stability Calculation of Power Systems Having Shunt Loads

The small signal performance of a multimachine power system is described by a set of differential equations of the form ＝Ax. The analysis includes the effect of local shunt loads and margin of stability defined in the eigenvalue-plane. The construction of the A-matrix involves an equivalent circuit of a transmission network, a hybrid reference frame and an axis transformation based on Park's transformation. Once the A-matrix is obtained, standard computer programs may be used for studying the dynamic stability characteristics of the power system. Root-locus analysis is adapted to get information on the dynamic stability of a sample model

Asynchronous Operation and Resynchronization of a Synchronous Machine in a Power System

The large signal performance of a multimachine power system is described by a set of differential equations of the form ＝f(x). The system disturbance caused by asynchronous operation of a synchronous machine in a power system was investigated by solving the system equations with the method of Runge-Kutta-Gill and the possibility of the resynchronization of an asynchronously operating machine was studied, using the method of phase plane analysis. The effects of control systems on the resynchronization of a machine were estimated

A bridge between robustness and simplicity: practical control design for complex systems

Automatic control design has been one of the major subjects in real-world system design/operation and is becoming much more significant today in accordance with increasing size, changing structure, uncertainties and complexity of artificial industry systems. A major challenge in a new environment is to integrate computing, communication and control into appropriate levels of real-world systems operation and control. In practice, many control systems usually track different control objectives such as stability, disturbance attenuation and reference tracking with considering practical constraints, simultaneously. At the moment in the industry applications, it is desirable to meet all specified goals using the controllers with simple structures. Since, practically these controllers are commonly designed based on experiences, classical and trial-and-error approaches, they are incapable of obtaining good dynamical performance to capture all design objectives and specifications for a wide range of operating conditions and various disturbances. It is significant to note that because of using simple structure, pertaining to the low-order control synthesis for dynamical systems in the presence of strong constraints and tight objectives are few and restrictive. Under such conditions, the synthesis process may not approach to a strictly feasible solution. Therefore, the most of robust and optimal approaches suggest complex state-feedback or high-order dynamic controllers. Moreover in the most of proposed approaches, a single performance criterion has been used to evaluate the robustness of resulted control systems. This research addresses three systematical, fast and flexible algorithms to design of low order or static output controllers for dynamical systems. The developed strategies attempt to invoke the strict conditions and bridge the gap between the power of optimal/robust control theory and industrial control design. To illustrate the effectiveness of the proposed control strategies, they have been applied to several complex systems in the electric industry

Impending Gastric Rupture in a Neonate with Gastric Outlet Obstruction due to Malrotation

This is a case report of a neonate with impending gastric rupture due to malrotation with gastric outlet obstruction. A preoperative plain abdominal X-ray showed expansion of the gastric bubble. A barium meal demonstrated an unusual bulging of the gastric wall extending from the fundus to the body of the stomach on the greater curvature side and malrotation of the duodenal loop. At operation a malrotation with volvulus and a rupture of the seromuscular layer with bulging of the mucosa in the stomach was found. We think that this unusual bulging of the gastric wall in the barium meal is an important radiological sign of impending gastric rupture

Fuzzy wavelet network identification of optimum operating point of non-crystalline silicon solar cells

The emerging non-crystalline silicon (c-Si) solar cell technologies are starting to make significant inroads into solar cell markets. Most of the researchers have focused on c-Si solar cell in maximum power points tracking applications of photovoltaic (PV) systems. However, the characteristics of non-c-Si solar cell technologies at maximum power point (MPP) have different trends in current???voltage characteristics. For this reason, determining the optimum operating point is very important for different solar cell technologies to increase the efficiency of PV systems. In this paper, it has been shown that the use of fuzzy system coupled with a discrete wavelet network in Takagi???Sugeno type model structure is capable of identifying the MPP voltage of different non-c-Si solar cells with very high accuracy. The performance of the fuzzy-wavelet network (FWN) method has been compared with other ANN structures, such as radial basis function (RBF), adaptive neuro-fuzzy inference system (ANFIS) and three layered feed-forward neural network (TFFN). The simulation results show that the single FWN architecture has superior approximation accuracy over the other methods and a very good generalization capability for different operating conditions and different technologie

Performance enhancement of photovoltaic array through string and central based MPPT system under non-uniform irradiance conditions

Energy Conversion and Management, Vol. 62, No. 10, pp. 131???140, 2012Mismatching losses reduction of photovoltaic (PV) array has been intensively discussed through the increasing penetration of residential and commercial PV systems. Many causes of mismatching losses have been identified and plenty of proposed methods to solve this problem have been recently proposed. This paper deals with reducing method of mismatching losses due to the non-uniform irradiance conditions. It is well-known that a certain number of multiple peaks occur on the power???voltage curve as the number of PV modules in one-string increases under non-uniform operating conditions. Since the conventional control method only drives the operating points of PV system to the local maxima close to open circuit voltage, only small portion of power can be extracted from the PV system. In this study, a radial basis function neural network (RBF-ANN) based intelligent control method is utilized to map the global operating voltage and non-irradiance operating condition in string and central based MPPT systems. The proposed method has been tested on 10 x 3 (2.2 kW), 15 x 3 (2.5 kW) and 20 x 3 (3.3 kW) of series???parallel PV array configuration under random-shaded and continuous-shaded patterns. The proposed method is compared with the ideal case and conventional method through a simple power-voltage curve of PV arrays. The simulation results show that there are significant increases of about 30-60% of the extracted power in one operating condition when the proposed method is able to shift the operating voltage of modules to their optimum voltages

Random phase-free kinoform for large objects

We propose a random phase-free kinoform for large objects. When not using the random phase in kinoform calculation, the reconstructed images from the kinoform are heavy degraded, like edge-only preserved images. In addition, the kinoform cannot record an entire object that exceeds the kinoform size because the object light does not widely spread. In order to avoid this degradation and to widely spread the object light, the random phase is applied to the kinoform calculation; however, the reconstructed image is contaminated by speckle noise. In this paper, we overcome this problem by using our random phase-free method and error diffusion method