Determination of weak transmission links by cluster analysis

Ertuğrul, Hamza Oğuz
Due to faults and switching, transmission lines encounter power oscillations referred as power swings. Although in most cases they do not lead to an eventual instability, severe changes in power flows on the lines may cause the operation of impedance relays incorrectly, leading to cascaded tripping of other lines. Out-of-Step tripping function is employed in modern distance relays to distinguish such an unstable swing but setting the parameters and deciding lines to be tripped require detailed dynamic power system modelling and analysis. The proposed method aims to determine possible out-of-step (OOS) locations on a power system without performing detailed dynamic simulations. Method presented here, is based on grouping of the buses by statistical clustering analysis of the network impedance matrix. Inter-cluster lines are shown to be more vulnerable to give rise to OOS as proven with dynamic simulations on IEEE 39 bus test system.


Prediction of hot-spot and top-oil temperatures of power transformers according to IEEE standards C57.110-1998 and C57.91-1995
Karaca, Haldun; Ermiş, Muammer; Department of Electrical and Electronics Engineering (2007)
In this thesis, the effects of Harmonics on the Top Oil and Hot Spot Temperatures of Power Transformers used in Turkish Electricity Transmission System have been investigated. Due to the solid state equipment, the harmonic levels increase. This effect raises the losses and temperatures in the transformer windings. None of the power transformers currently used in Turkey has measuring equipment suitable for measuring the Hot-Spot temperatures. In this study, a computer program is written in LABVIEW which meas...
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Güneri, Melih; Özay, Nevzat; Department of Electrical and Electronics Engineering (2006)
This thesis analyses the controlled switching methods applied to modern SF6 type circuit breakers for the purpose of reducing switching overvoltages. Main emphasis is placed on controlled switching methods applied at extra high voltage level, since the cost of failures caused by switching overvoltages is highest in this voltage level. After a brief introduction about circuit breakers in general, switching overvoltages and controlled switching methods are analysed. Also a case study about controlled switchin...
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Bilgin, Hazım Faruk; Ermiş, Muammer; Department of Electrical and Electronics Engineering (2007)
This research work is devoted to the analysis, design and development of the first medium power Current-Source Converter (CSC) based distribution-type Static Synchronous Compensator (D-STATCOM) with simplest converter topology and coupling transformer connection. The developed CSC-D-STATCOM includes a +/-750kVAr full-bridge CSC employing Selective Harmonic Elimination Method (SHEM), a 250kVAr low-pass input filter at 1kV voltage level, and a Δ/Y connected coupling transformer for connection to medium-voltag...
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Türkmen, Coşkun Aziz; Ermiş, Muammer; Department of Electrical and Electronics Engineering (2010)
It is known from the literature that conventional voltage and current transformers measure inaccurate values for voltage and current harmonics which are parts of power quality. Maximum bandwidth of conventional current transformers, which are used in electricity transmission and distribution systems, is 1.5-2 kHz and it is lower for conventional voltage transformers. Also, it is known that; voltages in some frequency spectrum are measured higher and voltages in another frequency spectrum are measured lower ...
Design and implementation of a voltage source converter based hybrid active power filter
Uçak, Onur; Ermiş, Muammer; Department of Electrical and Electronics Engineering (2009)
This research work is devoted to the analysis, design and implementation of a shunt connected Hybrid Active Power Filter by the use of a lower rated voltage source PWM converter, and a series connected LC passive filter. In recent years, voltage and current harmonics have become a serious problem both in transmission and distribution systems, due to the widespread usage of non-linear loads such as diode/thyristor rectifiers, electric arc furnaces and motor drives. In order to obtain a better performance tha...
Citation Formats
H. O. Ertuğrul, “Determination of weak transmission links by cluster analysis,” M.S. - Master of Science, Middle East Technical University, 2009.