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.

Increased Utilization of Wind Generation by Coordinating the Demand Response and Real-time Thermal Rating

Abstract: Demand response (DR) will play an essential role in smart grids by contributing to the operational flexibility requirement arising from the increased penetration of intermittent renewable generation. However, DR activation could be hampered in the absence of intelligent network management. Real-time thermal rating (RTTR) functions as a smart network management tool for unlocking the network capacities by allowing the network to safely operate during overload states. This paper offers an optimal residential DR approach integrated with RTTR to balance the hourly wind power production. The proposed framework is modeled from the perspective of an electrical aggregator that manages the population of heating, ventilation and air-conditioning (HVAC) loads for wind power balancing considering the RTTR of a distribution network. The model schedules the HVAC loads without deterioration of the customers' temperature preferences. To demonstrate the performance of the proposed approach, simulations are performed on a typical Finnish distribution network plan. The results demonstrate the considerable benefits that can be realized by coordinating the DR and RTTR in a distribution network for wind generation balancing.

Impact of MV Connected Microgrids on MV Distribution Planning

Abstract: The planning and development of distribution networks with a substantial penetration of microgrids connected to the medium voltage (MV) network form the main themes of this paper. The impact of microgrids is assessed in terms of their effect on optimal network topology, losses, reliability, reserve connections, network upgrade and expansion savings. The earning base of the distribution system operator also comes under scrutiny. A suburban MV cable network is planned using a network planning algorithm developed by the authors, first with optimal routing for demand-only nodes and then with a 33% penetration of randomly located microgrids. The network is then expanded to meet the requirements of a future planning horizon, in order to compare the expanded and upgraded optimum MV network topology with and without microgrids. Apart from visually depicting the topological differences, the savings such microgrids can give to the long term distribution network investment and running costs are quantified in terms of the investment costs, loss costs and interruption costs. When networks are planned with optimal rather than full backup, the introduction of microgrids is shown to have a considerable saving impact on all cost components except the cost per unit power transfer in the distribution network.

Optimal Energy Trading for Renewable Energy Integrated Building Microgrids Containing Electric Vehicles and Energy Storage Batteries

Abstract: The increasing penetration of renewable energy resources and volatility of energy prices cause huge challenges in planning and regulating energy generation, transport, and distribution. A possible solution can be a paradigm change of employing control actions from the demand side in addition to the conventional generation control. To realize such shifts, the primary stage should be a proper and robust analysis of the energy flexibility on the demand side. Recently, demand side control in buildings has become a major research issue because buildings share a substantial portion of the total electricity consumption. The increasing use of controllable devices in buildings combined with the advent of smart metering system has paved the way to exploit the potential flexibility of managing the energy generation and demand of buildings for optimal energy trading. In this paper, we investigate the benefits of demand resources in buildings for optimal energy trading in day-ahead and real-time energy markets. The building flexible demand resources considered are electric vehicles and batteries. The paper examines the combined optimization of EVs and batteries in the day-ahead and regulation electricity markets with the objective of maximizing the total profit of the building microgrid. It takes EVs driving pattern into consideration. The major contribution of the paper is the exploitation of the energy flexibility of buildings using EVs as dynamic energy storage device and batteries as manageable demand facility. The devised optimization problem is formulated as a double-stage mixed-integer linear programming (MILP) problem, and solved using the CPLEX solver. Several numerical results are presented to validate the effectiveness of the devised optimization framework using actual data of building electricity demand and local renewable generation in the Otaniemi area of Espoo, Finland. We demonstrate that the proposed optimization solution can achieve considerable increase in profit, reduce renewable energy curtailment and decrease power demand in peak hours, compared to uncontrolled or non-optimized operation.

A Model for Stochastic Planning of Distribution Network and Autonomous DG Units

Abstract: This article presents a mixed-integer linear stochastic model for the optimal expansion planning of electricity distribution networks and distributed generation (DG) units. In the proposed framework, autonomous DG units are aggregated and modeled using the well-known energy hub concept. In this model, the uncertainties of heat and electricity demand as well as renewable generation are represented using various scenarios. Although this is a standard technique to capture the uncertainties, it drastically increases the dimensions of this optimization problem and makes it practically intractable. In order to address this issue, a novel iterative method is developed in this article to enhance the efficiency of the optimization model. The proposed framework is further utilized to assess the benefits of the collaborative distribution network and autonomous distributed generation planning through various case studies performed on the 24-node distribution test grid. With 5.93% cost reduction, the obtained results indicate the importance of such collaborations in reaching an efficient network expansion solution. Moreover, the total planning cost for the stochastic model is 1.23% lower than the deterministic case. Various sensitivity analyses are also carried out to investigate the impacts of parameters of the proposed model on the optimal planning solution. The scalability of the model is also assessed by its implementation on the 54-node distribution test network.

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.