Browsing by Author "Yoldaş, Yeliz"

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DEVELOPMENT OF CONTROL STRATEGIES IN SMART MICROGRIDS
(Abdullah Gül Üniversitesi Fen Bilimleri Enstitüsü, 2021) Yoldaş, Yeliz; 0000-0002-9821-9339; AGÜ, Fen Bilimleri Enstitüsü, Elektrik ve Bilgisayar Mühendisliği Ana Bilim Dalı
This thesis concerns the transformation of aged power systems to modern power systems that include microgrids with renewable energy sources and energy storage systems. The integration of renewable energy sources brings excellent opportunities to provide better reliability and efficiency. The aim of this dissertation is to maintain the supply-demand balance in microgrids while minimizing the cost in real time operation. A microgrid energy management system that can optimize the dispatch of the controllable distributed energy resources in grid-connected mode of a pilot microgrid on a university campus in Malta was developed to achieve this goal. Designing intelligent method for the real-time energy management of the stochastic and dynamic microgrid is the primary goal of this research. Moreover, the detailed mathematical models of the network model and of the technical model are considered for the economic and environmental operation of the microgrid system to solve the optimization problem under more real-world conditions. The objective is to minimize the total daily operation costs, which include the degradation cost of batteries, the cost of energy bought from the main grid, the fuel cost of the diesel generator, and the emission cost. Q-learning algorithm is adopted to solve the sequential decision subproblems. The proposed algorithm decomposes a multi-stage mixed-integer nonlinear programming (MINLP) problem into a series of single-stage problems so that each subproblem can be solved using Bellman’s equation. A predictive control framework is also proposed to provide optimal operation with minimum cost. This method allows the consideration of operational cost values, demand with uncertainty, generation units’ profiles with uncertainty, and constraints related to the network model and technical model.
Dynamic rolling horizon control approach for a university campus
(Elsevier Ltd, 2022) Yoldas, Yeliz; Goren, Selcuk; Onen, Ahmet; Ustun, Taha Selim; 0000-0002-5320-4213; 0000-0001-7086-5112; 0000-0002-2413-8421; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Yoldaş, Yeliz; Gören, Selçuk; Önen, Ahmet
An energy management system based on the rolling horizon control approach has been proposed for the grid-connected dynamic and stochastic microgrid of a university campus in Malta. The aims of the study are to minimize the fuel cost of the diesel generator, minimize the cost of power transfer between the main grid and the micro grid, and minimize the cost of deterioration of the battery to be able to provide optimum economic operation. Since uncertainty in renewable energy sources and load is inevitable, rolling horizon control in the stochastic framework is used to manage uncertainties in the energy management system problem. Both the deterministic and stochastic processes were studied to approve the effectiveness of the algorithm. Also, the results are compared with the Myopic and Mixed Integer Linear Programming algorithms. The results show that the life span of the battery and the associated economic savings are correlated with the SOC values.
Mitigation of power quality problems using distribution static synchronous compensator: A comprehensive review
(Institution of Engineering and Technology, 2015) Latran, Mohammed Barghi; Teke, Ahmet; Yoldaş, Yeliz; 0000-0002-9821-9339; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Yoldaş, Yeliz
Electric power quality (PQ) in distribution system has become increasingly significant subject both for end users and power suppliers with the deregulation of the electric power market. The inadequate performance of conventional compensation devices to mitigate PQ problems has revealed the use of advanced power electronics based compensation devices. Distribution static synchronous compensator (DSTATCOM) is one of the shunt connected custom power devices used to improve PQ, voltage and reactive power support and to increase the capability of the auxiliary service for utility grid. This study presents a comprehensive review of the various DSTATCOM configurations for single-phase (two-wire) and three-phase (three or four-wire) systems and control strategies for the compensation of different PQ problems in distribution systems. In addition, comprehensive explanation, comparison and discussion on DSTATCOM technology are performed. Furthermore, latest trends, practical consideration and some future research fields on DSTATCOMs are discussed in detail. This is intended to present a broad perspective on the status of DSTATCOM technology to researchers dealing with compensation of PQ problems in distribution systems.
Step by Step Design Procedure of a Distribution Static Synchronous Compensator (DSTATCOM)
(ÇUKUROVA ÜNİVERSİTESİ, 2015) Teke, Ahmet; Yoldaş, Yeliz; Latran, Mohammad Barghi; 0000-0002-9821-9339; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Yoldaş, Yeliz
DSTATCOM is one of the power conditioning devices that is used to mitigate power quality problems in distribution systems. The overall performance of the DSTATCOM is strictly related with the proper selection of power circuit configuration and controller algorithm. The power circuit of DSTATCOM consists of dc link capacitor, inverter and passive filter. The control circuit of DSTATCOM consists of reference signal extraction, DC link voltage control, AC voltage control and switching signal generation. Compensating current reference signal is generally derived from the measured quantities by the use of the Instantaneous Symmetrical Component Theory (ISCT) and dq theory based method. A proportional integral (PI) controller is generally used to maintain a constant voltage at the dc-link of a Voltage-Source Inverter (VSI). Furthermore, by connecting a delta connected inductor-capacitor-inductor (LCL) passive filter at inverter output, the high order harmonics generated by the DSTATCOM can be easily and effectively eliminated. This study presents the design procedures for power and control circuits of 300 kVA DSTATCOM in detail.