Yönetim Bilişim Sistemleri Bölümü Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12469/68

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Applications of Eigenvalue Counting and Inclusion Theorems in Model Order Reduction
(Springer-Verlag Berlin, 2010) Yetkin, E. Fatih; Dağ, Hasan
We suggest a simple and an efficient iterative method based on both the Gerschgorin eigenvalue inclusion theorem and the deflation methods to compute a Reduced Order Model (ROM) to lower greatly the order of a given state space system. This method is especially efficient in symmetric state-space systems but it works for the other cases with some modifications.
Citation - WoS: 2
Citation - Scopus: 6
Branch Outage Simulation Based Contingency Screening by Gravitational Search Algorithm
(Praise Worthy Prize Srl, 2012) Ceylan, Oğuzhan; Özdemir, Aydoğan; Dağ, Hasan
Power systems contingency analysis is an important issue for electric power system operators. This paper performs branch outage simulation based contingency screening using a bounded network approach. Local constrained optimization problem representing the branch outage phenomena is solved by the gravitational search algorithm. The proposed method is applied to IEEE 14 30 57 and 118 Bus Test systems and its performance from the point of capturing violations is evaluated. In addition false alarms and the computational accuracy of the proposed method are also analyzed by using scattering diagrams. Finally the proposed gravitational search based contingency screening is compared with full AC load flow solutions from the point of computational speed. Copyright (C) 2012 Praise Worthy Prize S.r.l. - All rights reserved.
Citation - Scopus: 15
Branch outage solution using particle swarm optimization
(2008) Ceylan, Oğuzhan; Ozdemir, Aydogan; Dağ, Hasan
For post outage MW line flows and voltage magnitude calculations most of the methods use linear methods because of their simplicity. Especially for reactive power flow calculations one can face high errors. In this paper we use a minimization method that minimizes the errors resulting from the linear system model implementation. We solve the optimization problem using particle swarm optimization. We give some outage examples using IEEE 14 bus IEEE 30 bus and IEEE 57 bus data and compare the results with full ac load flow calculation. © 2008 Australasian Universities Power Engineering Conference (AUPEC'08).
Citation - Scopus: 17
Comparison of Feature Selection Algorithms for Medical Data
(IEEE, 2012) Dağ, Hasan; Sayın, Kamran Emre; Yenidoğan, Işıl; Albayrak, Songül Varli; Acar, Can
Data mining application areas widen day by day. Among those areas medical area has been receiving quite a big attention. However working with very large data sets with many attributes is hard. Experts in this field use heavily advanced statistical analysis. The use of data mining techniques is fairly new. This paper compares three feature selection algorithms on medical data sets and comments on the importance of discretization of attributes. © 2012 IEEE.
Citation - Scopus: 1
Distributed Memory Parallel Transient Stability Analysis on a Pc Cluster With Ethernet
(Praise Worthy Prize Srl, 2010) Soykan, Gürkan; Flueck, Alexander J.; Dağ, Hasan
On-line transient stability analysis is a necessity for real-time power system control and security. Parallel processing is a natural technology for achieving real-time solution performance. This paper presents a parallel-in-space algorithm based on a multi-level partitioning scheme in a distributed memory cluster environment. The main aim of the research is to decrease the wallclock time of transient stability analysis of large scale power systems by leveraging open source software and commodity off the shelf hardware of a Linux PC cluster. The proposed solution algorithm focuses on speeding up the transient stability simulation by partitioning via METIS the linearized update solution process of the Very Dishonest Newton Method for solving the differential-algebraic equation system. Results are presented for two power systems: I) 3493 buses 844 generators 6689 branches and 2) 7935 buses 2135 generators 13624 branches. The simulations were run on a small Linux-cluster with a 100 Mbit/s ethernet interconnect which is cheaper than any specially constructed parallel computer. By tuning vertex weights the performance of the partition strategy can be improved relative to the no-weight case. The proposed method easily can be adapted by commercial packages and used in various parallel environments including multicore architectures with non-uniform memory access. Copyright (C) 2010 Praise Worthy Prize S.r.l. - All rights reserved.
Citation - WoS: 2
Citation - Scopus: 2
Double Branch Outage Modeling and Simulation: Bounded Network Approach
(Elsevier Science, 2015) Ceylan, Oğuzhan; Özdemir, Aydoğan; Dağ, Hasan
Energy management system operators perform regular outage simulations in order to ensure secure operation of power systems. AC power flow based outage simulations are not preferred because of insufficient computational speed. Hence several outage models and computational methods providing acceptable accuracy have been developed. On the other hand double branch outages are critical rare events which can result in cascading outages and system collapse. This paper presents a double branch outage model and formulation of the phenomena as a constrained optimization problem. Optimization problem is then solved by using differential evolution method and particle swarm optimization algorithm. The proposed algorithm is applied to IEEE test systems. Computational accuracies of differential evolution based solutions and particle swarm optimization based solutions are discussed for IEEE 30 Bus Test System and IEEE 118 Bus Test System applications. IEEE 14 Bus Test System IEEE 30 Bus Test System IEEE 57 Bus Test System IEEE 118 Bus Test System and IEEE 300 Bus Test System simulation results are compared to AC load flows in terms of computational speed. Finally the performance of the proposed method is analyzed for different outage configurations. (C) 2015 Elsevier Ltd. All rights reserved.
A Generic Framework for Building Heterogeneous Simulations of Parallel and Distributed Computing Systems
(Springer Heidelberg, 2017) Dursun, Taner; Dağ, Hasan
There have been many systems available for parallel and distributed computing (PDC) applications such as grids clusters super-computers clouds peer-to-peer and volunteer computing systems. High-performance computing (HPC) has been an obvious candidate domain to take advantage of PDC systems. Most of the research on HPC has been conducted with simulations and has been generally focused on a specific type of PDC system. This paper however introduces a general purpose simulation model that can be easily enlarged for constructing simulations of many of the most well-known PDC system types. Although it might create a new vision for research activities in the simulation community current simulation tools do not provide proper support for cooperation between software working in real-time and simulation time. In this paper thus we also present a promising approach for constructing hybrid simulations that offers great potential for many research areas. As a proof of concept we implemented a prototype for our simulation model. Then we are able to rely on this prototype to build simulations of various PDC systems. Thanks to hybrid simulation support of our model we are able to combine and manage the simulated PDC systems with our previously developed policy-based management framework in simulation runs.
Citation - Scopus: 25
Gravitational Search Algorithm for Post-Outage Bus Voltage Magnitude Calculations
(2010) Ceylan, Oğuzhan; Ozdemir, Aydogan; Dağ, Hasan
Branch outage problem is one of the key problems in power system security analysis. This paper solves branch outage problem using a bounded approach. Local constrained optimization problem in the bounded approach is solved by the gravitational search algorithm. Test results of IEEE 14 30 and 118 bus systems are compared to those of ac load flow method in terms of both accuracy and speed.
Citation - Scopus: 4
Harmony Search Method Based Parallel Contingency Analysis
(2010) Ceylan, Oğuzhan; Dağ, Hasan; Ozdemir, Aydogan
Power system security management is one of the key problems in power system analysis. Power system management center operators need to simulate contingencies as fast as possible and take the remedial actions in time. These contingency analyses comprise of the outages of the branches transformers and other power system components. This paper solves branch outage problem using a bounded approach. Harmony search method is used to solve the local constrained optimization problem of the bounded approach. Several outage simulations using IEEE 14 30 and 118 bus systems are performed and compared against AC power flow in terms of accuracy. In order to speed up the contingency simulation the problem is also solved in a parallel environment. Speed up results of the IEEE 118 and 300 bus test systems are given. ©2010 IEEE.
Citation - Scopus: 1
Heterosim: Heterogeneous Simulation Framework
(Association for Computing Machinery, 2009) Dursun, Taner; Dağ, Hasan
In order to arrange heterogeneous simulation executions it would be useful to have simulation tools that enable easy and fast creation of simulation sessions employing real-time software components beside simulation codes. Although there have been considerable amount of research activities in simulation community the current simulation tools are not sufficiently capable to support such a cooperation between components working in real-time and simulation-time. In this paper we propose a new approach for constructing hybrid simulations that leverages usage of simulation systems. We introduce HeteroSim a Java-based simulation system that can execute discrete event simulations by employing both simulation and real world software entities. This model is applicable to many software related areas such as scenario-based software testing and development of simulators. As a case study we are able to rely on this model in order to build simulations combining both the simulated elements of a High Performance Computing (HPC) system and already implemented elements of our Policy Based Management (PBM) framework so-called POLICE [1][2]. In this manner it may be possible to study the efficiency of POLICE on management of HPC systems.
Citation - WoS: 5
Citation - Scopus: 5
Heuristic Methods for Postoutage Voltage Magnitude Calculations
(TUBITAK Scientific & Technical Research Council Turkey, 2016) Ceylan, Oğuzhan; Özdemir, Aydogan; Dağ, Hasan
Power systems play a significant role in every aspect of our daily lives. Hence their continuation without any interruption (or with the least duration of interruption due to faults or scheduled maintenances) is one of the key aims of electrical energy providers. As a result electrical energy providers need to check in great detail the integrity of their power systems by performing regular contingency studies of the equipment involved. Among others line and transformer outage simulations constitute an integral part of an electrical management system. Both accuracy and calculation speed depend on the branch outage model and/or the solution algorithms applied. In this paper the local constrained optimization problem of the single-branch outage problem is solved by intelligent methods: particle swarm optimization differential evolution and harmony search. Simulations of IEEE 14- 30- 118- and 300 -bus systems are computed both by intelligent methods and by AC load flow. The results of the intelligent method -based simulations and AC load flow -based simulations are compared in terms of accuracy and computation speed.
Implementation of a Sdn (software Defined Network)
(International Institute of Informatics and Systemics IIIS, 2014) Ergen, Mithat Sinan; Kutlan, Sarp; Dağ, Tamer; Dağ, Hasan
Improving resource efficiency enhancing network security and achieving simpler network management have become the main goals for networking in the previous years. To accomplish these ideas an efficient routing traffic monitoring access control and server load balancing systems need to be designed. However these objectives make the optimization and management of networks rather difficult. In this paper Software Defined Networks (SDN) an alternative way for creating an optimized network by taking into account the difficulties met today is introduced. Software Defined Networks provide the separation of control and data planes for the switches which allows programming for a customized control plane. With simplified network management through SDN it can be possible to dynamically adjust the behavior of the network equipment independently from equipment manufacturers. New mechanisms with new potential benefits can easily be explored and used. Quality of Service and network security problems can be solved rapidly. In this paper it is described how to build a virtualized SDN in order to show the benefits of SDN over a distributed network. Virtualization can provide deployment and delivery flexibility cost savings and improved user experience.
Citation - WoS: 2
Citation - Scopus: 2
A New Preconditioner Design Based on Spectral Division for Power Flow Analysis
(Praise Worthy Prize Srl, 2011) Dağ, Hasan; Yetkin, E. Fatih; Manguoglu, Murat
Solution of large sparse linear systems is the most lime consuming part in many power system simulations. Direct solvers based on LU factorization although robust are known to have limited satiability on parallel platforms. Thus. Krylov subspace based iterative methods (i.e. Conjugate Gradient method Generalized Minimal Residuals (GMRES) method) can be used as alternatives. To achieve competitive performance and robustness however the Krylov subspace methods need a suitable preconditioner. In this work we propose a new preconditioner iterative methods which can be used in Newton-Raphson process of power flow analysis. The suggested preconditioner employs the basic spectral divide and conquer methods and invariant subspaces for clustering the eigenvalues of the Jacobian matrix appearing in Newton-Raphson steps of power flow simulation. To obtain the preconditioner we use Matrix Sign Function (MSF) and to obtain the MSF itself we use Sparse Approximate Inverse (SPAI) algorithm with Newton iteration. We compare the convergence characteristics of our preconditioner against the well-known black-box preconditioners such as incomplete-LU and SPAI. Copyright (C) 2011 Praise Worthy Prize S.r.l. - All rights reserved.
On the Selection of Interpolation Points for Rational Krylov Methods
(Springer-Verlag Berlin, 2012) Yetkin, E. Fatih; Dağ, Hasan
We suggest a simple and an efficient way of selecting a suitable set of interpolation points for the well-known rational Krylov based model order reduction techniques. To do this some sampling points from the frequency response of the transfer function are taken. These points correspond to the places where the sign of the numerical derivation of transfer function changes. The suggested method requires a set of linear system's solutions several times. But they can be computed concurrently by different processors in a parallel computing environment. Serial performance of the method is compared to the well-known H-2 optimal method for several benchmark examples. The method achieves acceptable accuracies (the same order of magnitude) compared to that of H-2 optimal methods and has a better performance than the common selection procedures such as linearly distributed points.
On-Line Transient Stability Assessment Using Matlab Parallel Programming Environment
(IEEE, 2010) Soykan, Gürkan; Dağ, Hasan
Transient Stability Assessment (TSA) is the major part of Dynamic Security Assessment (DSA) in an electric power system. On-line TSA has gained more importance for power system security in last two decades. The decreasing costs of hardware and advanced package programs and techniques encourage researchers to apply parallel programming to the problems that are either too much time consuming or impossible to solve using serial computers. The real-time evaluation of TSA is now almost possible thanks to such tools and techniques. We demonstrate the use of the parallel computing toolbox of Mat lab for TSA. In this regard IEEE 57 and 118 bus systems are tested with 57 and 56 contingencies respectively. Each contingency requires solution of a transient stability problem. The parallel performance of this implementation is expected to spur researchers to use parallel programming in Mat lab environment. It requires minimal knowledge regarding parallel programming.
Citation - Scopus: 1
Parallel Contingency Analysis Using Differential Evolution Based Solution for Branch Outage Problem
(IEEE, 2010) Ceylan, Oğuzhan; Dağ, Hasan; Özdemir, Aydoğan
Contingency analysis is one of the most fundamental work an electricity management center operator has to perform regularly. If both bus voltage magnitudes and reactive power flowing on the branches during any type of outages are within the acceptable limits the system is called secure. In this paper we solve the contingency problem using a recently developed local constrained optimization based branch outage problem. The optimization problem resulted from the formulation of branch outage is solved by differential evolution method. Using Matlab's parallel computing toolbox contingency analysis for IEEE 300 test system is performed and the results are presented. The study shows that it is straight forward to implement contingency analysis on the Matlab's parallel environment and obtain near linear speedups.
Parallel Implementation Of Iterative Rational Krylov Methods For Model Order Reduction
(IEEE, 2010) Yetkin, E. Fatih; Dağ, Hasan
Model order reduction (MOR) techniques are getting more important in large scale computational tasks like large scale electronic circuit simulations. In this paper we present some experimental work on multiprocessor systems for rational Krylov methods. These methods require huge memory and computational power especially in large scale simulations. Therefore these methods are fairly suitable for parallel computing.
Citation - Scopus: 2
Parallel Implementation of Iterative Rational Krylov Methods for Model Order Reduction
(IEEE, 2009) Yetkin, Emrullah Fatih; Dağ, Hasan
Model order reduction (MOR) techniques are getting more important in large scale computational tasks like large scale electronic circuit simulations. In this paper we present some experimental work on multiprocessor systems for rational Krylov methods. These methods require huge memory and computational power especially in large scale simulations. Therefore these methods are fairly suitable for parallel computing. ©2009 IEEE.
Citation - Scopus: 6
Parallel-In Implementation of Transient Stability Analysis on a Linux Cluster With Infiniband
(IEEE, 2012) Soykan, Gürkan; Flueck, Alexander J.; Dağ, Hasan
On-line transient stability analysis is an inevitable way to provide real time power system security and control. Parallel computing is one of the most viable ways to perform on-line transient stability analysis. This paper presents the performance results of a parallel-in-space algorithm based on a multilevel partitioning scheme on an Infiniband cluster system. The algorithm decreases the transient stability simulation time using METIS for partitioning in conjunction with the linearized update solution process of the Very Dishonest Newton Method when solving the differential-algebraic systems of equations [1]. Two real power systems a 3493-bus system with 844 generators and a 7935-bus system with 2135 generators are tested on a Linux-cluster system with 16 nodes. Each node has 2 multicore processors and is connected to each other by Infiniband network. The properties of a test system have a large impact on the performance of the parallel algorithm used since it affects communication duration. © 2012 IEEE.
Citation - Scopus: 2
Post Outage Bus Voltage Calculations for Double Branch Outages
(IEEE, 2012) Ceylan, Oğuzhan; Ozdemir, Aydogan; Dağ, Hasan
Secure operation of electrical power systems is vital hence fast and accurate post-outage state calculations are important for contingency analysis. Contingency analysis includes simulations of both the single and double branch outages. This paper presents constrained optimization problem of a recently developed double branch outage model. Harmony search algorithm is used as an optimization tool. IEEE 30 Bus Test system simulation results are given and compared with those of the AC load flow in terms of computational accuracy. Speed test results of IEEE 14 30 57 118 and 300 Bus Test Systems are illustrated and compared with those of the AC load flow calculations. © 2012 IEEE.

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