Matti Lehtonen

Bio: Matti Lehtonen is an academic researcher from Aalto University. The author has contributed to research in topics: Fault (power engineering) & Electric power system. The author has an hindex of 40, co-authored 694 publications receiving 8559 citations. Previous affiliations of Matti Lehtonen include Razi University & New York University.

Overvoltage spikes transmitted through distribution transformers due to MV spark-gap operation

Abstract: Small distribution transformers are often protected with spark gaps. As the spark-gap ignites, an overvoltage is coupled to the secondary side due to the steep voltage change. This overvoltage can reach to the customer socket. In this paper, the breakdown of MV spark-gaps is first modeled under an impulse voltage superimposed on AC voltage. To study the overvoltage propagation to the low voltage side, an accurate and simplified high frequency transformer model is used. The model, MV spark-gap and LV network are combined in ATP/EMTP to study the overvoltage spike propagation. Finally, the low voltage surge arrester at the secondary terminals of the distribution transformer is investigated for overvoltage mitigation.

Toward Operational Resilience of Smart Energy Networks in Complex Infrastructures

Abstract: Smart energy systems can mitigate electric interruption costs provoked by manifold disruptive events via making efforts toward proper pre-disturbance preparation and optimal post-disturbance restoration. In this context, effective contingency management in power distribution networks calls for contemplating disparate parameters from interconnected electric and transportation systems. This chapter, while considering transportation issues in power networks’ field operations, presents a navigation system for pre-positioning resources such as field crews and reconfiguring the network to acquire a more robust configuration in advance of the imminent catastrophe. Also, after the occurrence of the calamity, this navigator optimally allocates the resources to recover the devastating system. So, providing a coordination framework for manual field operation and automation system, this navigator takes a step from traditionally operated systems accommodation toward smart networks. During the contingency management process, there might be modifications in initial data due to the dynamic and time-varying condition of electric and transportation systems. Therefore, the mentioned navigator copes with a real-time problem of data-driven decision making in which, the decisions need to track online changes to the input data. Decision making by the navigation system in this environment is based on a mixed integer linear programming (MILP) optimization which is described in this chapter in detail.

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 …

The Design and Analysis of Experiments

Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

World energy outlook

Abstract: This chapter discusses leading problems linked to energy that the world is now confronting and to propose some ideas concerning possible solutions. Oil deserves special attention among all energy sources. Since the beginning of 1981, it has merely been continuing and enhancing the downward movement in consumption and prices caused by excessive rises, especially for light crudes such as those from Africa, and the slowing down of worldwide economic growth. Densely-populated oil-producing countries need to produce to live, to pay for their food and their equipment. If the economic growth of the industrialized countries were to be 4%, even if investment in the rational use of energy were pushed to the limit and the development of nonpetroleum energy sources were also pursued actively, it would be extremely difficult to prevent a sharp rise in prices. It is evident that it is absolutely necessary to pursue actively the development of coal, natural gas, and nuclear power if a physical shortage of energy is not to block economic growth.