Digital Modelling of the Excitation and Short-Circuit Transient Characteristics of the Short-Circuit Generators

Examensarbete för masterexamen

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Type: Examensarbete för masterexamen
Master Thesis
Title: Digital Modelling of the Excitation and Short-Circuit Transient Characteristics of the Short-Circuit Generators
Authors: Kinčeš, Marian
Abstract: High Power Laboratory in Ludvika has facilities for short-circuit testing of high voltage equipment like circuit breakers, disconnectors, surge arresters, transformers, switchgear cubicles, etc.; simulating the test conditions as in real power transmission network. In order to provide such an extremely high short-circuit current up to 100kA, two specially designed turbo-generators are being used with a total capacity of 4000MVA. Each of generators during the short-circuit test is excited by a separate driven exciter to provide the excitation current. Flying excitation method which is used to provide the right value of test current and voltage is described more in detail in Chapter 2. The excitation system has to be properly set in order to satisfy requirements of short-circuit testing. Therefore correct value of excitation time and an exciter voltage has to be chosen in advance to fulfil the criteria of short-circuit testing. The no-load characteristics of generators have been measured and an analysis of obtained data was made to get the needed excitation time characteristics. The study of collected data from previous single-phase short-circuit tests showed that it is best to use the same excitation times for the operating sequences open (O), open-close-open (O-CO) and close-open (CO) in order to provide the correct short-circuit current at interruption for a given connection of generator winding, and frequency. For operating sequence close (C) is also recommended to use the same excitation time determined in the study for whole range of short-circuit current at the generator side within the same generator winding connection, frequency and use of the generators. The final program for calculation of excitation parameters has been developed to visualise the particular excitation time characteristics obtained from the no-load measurements as well as easily and accurately determine the right values of parameters for excitation of the generator, such as exciter voltage and generator output rms voltage, for a certain short-circuit test. Recommended excitation times can be also easily found in the program by various combinations of the input parameters like generator, frequency, winding connection and operating sequence.
Keywords: Elkraftteknik;Electric power engineering
Issue Date: 2006
Publisher: Chalmers tekniska högskola / Institutionen för energi och miljö
Chalmers University of Technology / Department of Energy and Environment
Collection:Examensarbeten för masterexamen // Master Theses

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