Yasunori Mitani

Bio: Yasunori Mitani is an academic researcher from Kyushu Institute of Technology. The author has contributed to research in topics: Electric power system & Automatic frequency control. The author has an hindex of 27, co-authored 304 publications receiving 3157 citations. Previous affiliations of Yasunori Mitani include Osaka University.

Intelligent Frequency Control in an AC Microgrid: Online PSO-Based Fuzzy Tuning Approach

Abstract: Modern power systems require increased intelligence and flexibility in the control and optimization to ensure the capability of maintaining a generation-load balance, following serious disturbances. This issue is becoming more significant today due to the increasing number of microgrids (MGs). The MGs mostly use renewable energies in electrical power production that are varying naturally. These changes and usual uncertainties in power systems cause the classic controllers to be unable to provide a proper performance over a wide range of operating conditions. In response to this challenge, the present paper addresses a new online intelligent approach by using a combination of the fuzzy logic and the particle swarm optimization (PSO) techniques for optimal tuning of the most popular existing proportional-integral (PI) based frequency controllers in the ac MG systems. The control design methodology is examined on an ac MG case study. The performance of the proposed intelligent control synthesis is compared with the pure fuzzy PI and the Ziegler-Nichols PI control design methods.

Robust decentralised load-frequency control using an iterative linear matrix inequalities algorithm

Abstract: The load-frequency control (LFC) problem has been one of the major subjects in electric power system design/operation and is becoming much more significant today in accordance with increasing size, changing structure and complexity of interconnected power systems. In practice LFC systems use simple proportional-integral (PI) controllers. However, since the PI controller parameters are usually tuned based on classical or trial-and-error approaches, they are incapable of obtaining good dynamical performance for a wide range of operating conditions and various load changes scenarios in a multi-area power system. For this problem, the decentralised LFC synthesis is formulated as an HN-control problem and is solved using an iterative linear matrix inequalities algorithm to design of robust PI controllers in the multi-area power systems. A three-area power system example with a wide range of load changes is given to illustrate the proposed approach. The resulting controllers are shown to minimise the effect of disturbances and maintain the robust performance. List of symbols Dfi frequency deviation DPgt governor valve position DPci governor load setpoint DPti turbine power DPtiei net tie-line power flow DPdi area load disturbance

Optimal location assignment and design of superconducting fault current limiters applied to loop power systems

Abstract: Short-circuit current is strongly related to the cost of apparatus and the efficient use of power transmissions. Therefore, the introduction of Superconducting Fault Current Limiters (SFCL's) becomes an effective way for suppressing such a high short-circuit current in loop power systems. Firstly, a method to obtain a smaller SFCL capacity by observing the SFCL behavior including sub-transient and transient effects during a short circuit is proposed. Secondly, we propose using a micro-genetic algorithm (micro-GA) combined with a hierarchical genetic algorithm (HGA) to simultaneously search for the optimal location and the smallest SFCL capacity. The efficiency of the proposed method is shown by numerical examples with a loop power system.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Artificial neural networks

Abstract: Artificial neural networks (ANNs) constitute a class of flexible nonlinear models designed to mimic biological neural systems. In this entry, we introduce ANN using familiar econometric terminology and provide an overview of ANN modeling approach and its implementation methods. † Correspondence: Chung-Ming Kuan, Institute of Economics, Academia Sinica, 128 Academia Road, Sec. 2, Taipei 115, Taiwan; ckuan@econ.sinica.edu.tw. †† I would like to express my sincere gratitude to the editor, Professor Steven Durlauf, for his patience and constructive comments on early drafts of this entry. I also thank Shih-Hsun Hsu and Yu-Lieh Huang for very helpful suggestions. The remaining errors are all mine.

Energy function analysis for power system stability

Abstract: (1990). ENERGY FUNCTION ANALYSIS FOR POWER SYSTEM STABILITY. Electric Machines & Power Systems: Vol. 18, No. 2, pp. 209-210.

AC-microgrids versus DC-microgrids with distributed energy resources: A review

Abstract: This paper presents the latest comprehensive literature review of AC and DC microgrid (MG) systems in connection with distributed generation (DG) units using renewable energy sources (RESs), energy storage systems (ESS) and loads. A survey on the alternative DG units' configurations in the low voltage AC (LVAC) and DC (LVDC) distribution networks with several applications of microgrid systems in the viewpoint of the current and the future consumer equipments energy market is extensively discussed. Based on the economical, technical and environmental benefits of the renewable energy related DG units, a thorough comparison between the two types of microgrid systems is provided. The paper also investigates the feasibility, control and energy management strategies of the two microgrid systems relying on the most current research works. Finally, the generalized relay tripping currents are derived and the protection strategies in microgrid systems are addressed in detail. From this literature survey, it can be revealed that the AC and DC microgrid systems with multiconverter devices are intrinsically potential for the future energy systems to achieve reliability, efficiency and quality power supply.