Endüstri Mühendisliği Bölümü Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12469/48

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A Comparative Study of Energy Models for Turkish Electricity Market Using Leap
(IEEE Computer Society, 2019) Massaga, Daniel Julius; Kirkil, Gökhan; Çelebi, Emre
Fossil fuel thermal power plants constitute a large part of the Turkish electricity generation capacity. Turkish government has been developing several energy policy documents to evaluate how various renewable energy sources of the country can be utilized optimally in the generation of electricity within the next 30 years. This study considers three scenarios in the transition to renewable energy for Turkey; the business as usual (BAU), energy conservation (EC) and renewable energy (REN) scenarios. EC scenario considers the use of energy-efficient appliances and imposing a carbon tax, whereas REN scenario considers increasing the share of the renewable energy sources as much as possible in the power generation mix. These scenarios were evaluated in terms of cost and environmental impact. The LEAP (Long-range Energy Alternatives Planning Model) was used in the research. The REN scenario has been shown to be the optimal energy policy option for Turkey in terms of cost and environmental impact.
Citation - WoS: 1
Citation - Scopus: 1
The Critical Point of a Sigmoidal Curve
(Babeș-Bolyai University, 2020) Bilge, Ayşe Hümeyra; Özdemir, Yunus
Let y(t) be a monotone increasing curve with lim(t ->+/-infinity) y((n))(t) = 0 for all n and let t(n) be the location of the global extremum of the nth derivative y((n))(t). Under certain assumptions on the Fourier and Hilbert transforms of y(t), we prove that the sequence {t(n)} is convergent. This implies in particular a preferred choice of the origin of the time axis and an intrinsic definition of the even and odd components of a sigmoidal function. In the context of phase transitions, the limit point has the interpretation of the critical point of the transition as discussed in previous work [3].
Electricity Market Equilibrium Models With Dynamic Demand Functions
(2013) Çelebi, Emre
Many electricity market models have either mostly ignored the demand response to changing prices (e.g. day-ahead models with mostly fixed demand) or at the other extreme they assumed that the full demand response occurred within one hour. Moreover the capital stock adjustment and the forward-looking nature of consumers are usually omitted. In this paper we propose variational inequality models for electricity markets with dynamic demand models where the intertemporal nature of consumption (i.e. the current consumption decision affects capital stock/habits and thus the future preferences and demand) is recognized. It is intended that the proposed models would develop a framework for electricity market equilibrium models that incorporate the dynamics of the demand side. © 2013 IEEE.
Citation - WoS: 3
Citation - Scopus: 3
An Equivalence Class Decomposition of Finite Metric Spaces Via Gromov Products
(Elsevier Science Bv, 2017) Bilge, Ayşe Hümeyra; Çelik, Derya; Koçak, Şahin
Let (X, d) be a finite metric space with elements P-i, i = 1,..., n and with the distance functions d(ij) The Gromov Product of the "triangle" (P-i, P-j, P-k) with vertices P-t, P-j and P-k at the vertex Pi is defined by Delta(ijk) = 1/2(d(ij) + d(ik) - d(jk)). We show that the collection of Gromov products determines the metric. We call a metric space Delta-generic, if the set of all Gromov products at a fixed vertex P-i has a unique smallest element (for i = 1,., n). We consider the function assigning to each vertex P-i the edge {P-i, P-k} of the triangle (P-i, P-j, P-k) realizing the minimal Gromov product at P-i and we call this function the Gromov product structure of the metric space (X, d). We say two Delta-generic metric spaces (X, d) and (X, d') to be Gromov product equivalent, if the corresponding Gromov product structures are the same up to a permutation of X. For n = 3, 4 there is one (Delta-generic) Gromov equivalence class and for n = 5 there are three (Delta-generic) Gromov equivalence classes. For n = 6 we show by computer that there are 26 distinct (Delta-generic) Gromov equivalence classes. (C) 2017 Elsevier B.V. All rights reserved.
Flow Structure in a Shallow Mixing Layer Developing Over 2-D Dunes
(E D P Sciences, 2018) Kirkil, Gökhan
A high resolution Detached Eddy Simulation (DES) are used to characterize the evolution of a shallow mixing layer developing between two parallel streams in a long open channel over two-dimensional (2D) dunes. The study discusses the vertical non-uniformity in the mixing layer and provides a quantitative characterization of the growth of the large-scale quasi 2D coherent structures with the distance from the splitter plate. The presence of large-scale roughness elements in the form of an array of two-dimensional dunes with a maximum height of 0.25D (D is the channel depth) induces a very rapid and larger shift of the centerline of the mixing layer due to the increased influence of the bottom roughness. Results show that in streamwise sections situated after 100D (D is the channel depth) from the splitter plate, the width of the mixing layer close to the free surface stays constant. The tilting of the mixing layer interface toward the low speed stream is observed as the free surface is approached in all vertical sections.
Citation - WoS: 2
Citation - Scopus: 2
Generation/Transmission Investment Planning Integrated With Market Equilibrium Models in Electricity Markets
(IEEE Computer Society, 2017) Çelebi, Emre
This paper introduces integrated models for transmission investments anticipating the generation investments and market-clearing equilibrium. Market-clearing models for deregulated electricity markets can inform decision makers on price signals formed in the competitive market other investor's and/or generator's behaviors underlying these price signals and new generation/transmission investment decisions. Bi-level programming problems are formed for this integrated models and reformulated by using mathematical programs with equilibrium constraints (MPEC). A simultaneous optimization model (as mixed complementarity problem-MCP) is proposed to compute the same equilibrium solution of the MPEC problem. The proposed MCP model is found to be computationally more efficient than the traditional MPEC reformulations on a simple 3-bus example. These models will be useful in planning generation/transmission investments and analyzing the relations among these investments and the market outcomes. © 2017 IEEE.
Citation - WoS: 3
Citation - Scopus: 6
Reformulations of a Bilevel Model for Detection of Tacit Collusion in Deregulated Electricity Markets
(IEEE Computer Society, 2019) Çelebi, Emre; Şahin, Güvenç; Esmaeili Aliabadi, Danial
In this study, we consider a collusion model for competitive pool based electricity markets operated by an independent system operator (ISO), where it aims to prevent tacit collusion among generators. In order to determine the existence of tacit collusion in the market, we have employed the the game-Theoretic bilevel optimization model proposed by [1]. This model represents the market clearing mechanism, where generators determine their bids in order to maximize their profit while the system operator allocates power and determine locational electricity prices. The resulting optimization problem is a bilevel multi-criteria problem with non-linear terms, which is already complex and difficult to solve. We provide reformulations and linearization methods to obtain equivalent problems, e.g., a mathematical problem with equilibrium constraints (MPEC), a mixed integer non-linear problem (MINLP) and a mixed integer problem (MIP). A simple 6-bus system is used to test the rate of detection for collusive states for the reformulations and the results are presented. We have found that MIP models and reformulations detect strong collusive states. This model can guide ISOs in identifying and preventing cases of generator collusion.
Citation - Scopus: 1
Turkey - Romania Subsea Transmission Cable Investment: Time for Reconsideration?
(2013) Guler, Burak; Fuller, David J.; Çelebi, Emre; Nathwani, Jatin S.
Transmission investment is important for integrating electricity markets operated by different countries/transmission system operators (TSOs). Turkey and Romania have proposed a transmission cable linking the transmission network between two countries under the Black Sea but this investment has been found infeasible due to the insufficient technical and financial benefits to the countries/TSOs. Now there may be a case for revisiting this project given emerging national and global policy frameworks leading to a 'shadow price' for carbon requiring decision analysis for investments to be guided by an explicit accounting of carbon-constraints. We propose a method that estimates the overall net benefit investing in this project by evaluating the project from the following perspectives: (1) economics where the energy resources of both countries are better utilized by evaluating the electricity supply and demand of each country (2) financial where the additional access to European electricity markets brings more trades in when the two promising markets are physically coupled (3) environmental where the effect of emission constraints are introduced. © 2013 IEEE.

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