Enerji sistemlerinde geçici olayların analizinde bilgisayar desteğinin etkisi
The Effect of computer aid on analysis of power system transients
- Tez No: 39117
- Danışmanlar: PROF.DR. NESRİN TARKAN
- Tez Türü: Yüksek Lisans
- Konular: Elektrik ve Elektronik Mühendisliği, Electrical and Electronics Engineering
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 1993
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 115
Özet
ÖZET Elektrik enerji sistemlerinde açma-kapama olayları sonucunda çok kısa süreli fakat normalden çok daha aşırı şiddetli meydana gelen gerilim ve akımlar sistemi oluşturan elemanları oldukça zorlar. Özellikle çok yüksek gerilim sis temlerinde boyutlandırma bu tür akım ve gerilimlere göre yapılır. Bu çalışmada amaç, hem enerji sistemlerinde meydana gelen geçici olayları kısaca gözden geçirmek, hem de bugüne kadar kullanılmış geçici olay analiz yöntemlerini inceledikten sonra genel amaçlı bir bilgisayar paket programının da bu iş için kullanılabilirliğini tartışmak olacaktır. Buna göre tezin ikinci bölümünde geçici olay incelemeline temel teşkil eden R-L, R-C, R-L-C devreleri ele alınarak bunların DC ve AC kaynaklara bağlanması durumunda diferansiyel denklemler yazılarak, çözümleri hakkında bazı yorumlar yapılmıştır. Üçüncü bölümde ise Enerji sistemlerinde meydana gelen aşırı gerilimler dış aşın ve iç aşırı gerilimler olarak iki gruba ayrılarak, anahtarlama olayları sonu cunda meydana gelen iç aşırı gerilimler alt bölümlere ayrılmıştır. Dördüncü bölümde enerji sistemlerinde geçici olaylara neden olan belli başlı olaylar ele alınmıştır. Bunun haricinde her alt bölümde, meydana gelen geçici olayları azaltma yollan tartışıldıktan sonra ayrıca geçici iç aşın gerilimlerin azaltılması adı altında alt bölümde konu teorik olarak incelenmiştir. Beşinci bölüm geçici olay incelemelerinde en önemli yardımcı eleman olan Geçici Rejim Analizörü'ne (GRA) ayrılmıştır. Bu amaçla GRA'nın nasıl kurulduğu, kurulmuş olan bir GRA'da hangi tür analizlerin yapılacağı hem genel olarak, hem de bir örnek üzerinde incelenmiştir. Son bölüm olan altıncı bölümde, sayısal bilgisayar destekli geçici olay anal izi üzerinde durulmuş, bu amaçla geçici olayların bilgisayar ile analizinde kullanılan matematiksel modeller tanıtıldıkdan sonra sayısal simülasyonda kullanılan Pspice paket programı kısaca ele alınmıştır. Son olarak Türkiye Ulusal Elektrik Şebekesinden ele alman bir şebeke parçası üzerinde Pspice yardımıyla çeşitli geçici olay analizleri yapılmıştır. Analiz sonuçları açısından değerlen dirildiğinde, Pspice'in geçici olay analizi için uygun olduğu ancak çok büyük sistemler için bazı dezavantajlan olduğu görülmüştür.
Özet (Çeviri)
SUMMARY THE EFFECT OF COMPUTER AID ON ANALYSIS OF POWER SYSTEM TRANSIENTS Switching operations cause high frequency transient oscillations of very short duration in electrical transmission systems. In the course of such transient phenomena, various points of the system are subjected to over voltage stresses. Since the beginning of the century, extensive works of theoretical and exper imental basis have been carried out about this subject. In the past, attempts were made to find analytical solutions for integro-differential equations written for distributed-parameter models of power systems. Unfortunately, even though many assumptions were made to simplify the solution of the problem, calcula tions were laborious and time consuming. In recent years, solution in time domain of system equations has become easy by using of digital computers. The switching event in a power system initiates the transition between two steady-state conditions, the pre-switching condition and post-switching condi- tion.Switching means, not only opening or closing of a circuit breaker on pur pose, but also taking form of a fault, restriking in a breaker, clearing of a fault by fuse blowing, so forth. For a DC circuit, the energy stored in various in ductances and capacitances are constant in steady-state. But in an AC circuit, energy is continually exchanged between circuit inductances and capacitances. Depending upon resistances of the system, losses will extract energy which will be supplied by various sources within the system. Each steady-state condition entails its own tmique set of energy storage and exchange rates. Thus a redistribution of energy must occur among the various system el ements to change from one steady-state condition to another. This change cannot occur immediately. In a certain period of time, this energy exchange will be carried out by transient voltages and currents. These transient voltages and currents develop in a orderly manner, which is prescribed by the network topology and conditions before and after switching event. Timing of switching event affects the characteristic of transients. These transient voltages and currents are damped and natural-frequency oscillations which are much greater than normal. Solution of the transient problems is based on Kirchoff laws. Since quantities are changing throughout the transient VIperiod, the mathematics describing transients involves differantial equations. Therefore, classical mathematical computation of transients requires a certain degree of mathematical proficiency and effort. In order to eliminate these difficulties, many aids have been improved since 1930's. The earliest aid to analysis of power system transients were so-called me chanical differantial analyzers and later electronic differantial analyzers called analog computers. These devices assist the solution of differantial equations representing transient phenomena. Since power system consists of some non linear devices, such as reactor and transformer, analog computer was unusable. This led to the electromagnetic model approach in which electric power system elements are represented by miniature counterparts. These are identical elec tric and magnetic response to harmonics, travelling and waves switching surges. This electromagnetic model system is called transient network analyzer(TNA). But now, In limited areas digital computer are replacing the TNA. For simple system arrangments without nonlineer devices, some digital computer programs offer an economical alternative to the TNA. Digital computer aided transient analysis consists of building a mathematical model for the entire system, then solving the state equations in the time domain. All possible switching and fault conditions can be simulated in this way, in order to predict the complete behavior of the system. Data Required for a Switching Transient Study Compared to conventional power system studies, switching transient anal ysis data requirements are often more detailed and unusual or special. These requirements remain essentially unchanged regardless of basic analysis tools and aids. The generalized data listed below encompass virtually all information areas required in a power system switching transient study: (1) One-line diagram of the system showing all circuits elements and connection options. (2) Impedances R, Xl, Xc both positive and zero sequence, representing utility system and its maximum and minimum voltage limits. (3) Individual power transformer data and other transformer data, if any. These are followings; - Rating, connections, no-load tap voltages, - No-load saturation data: Curve of no-load voltage versus exciting cur rent, additionally specifying rated voltage, magnetizing impedances, and vnair core impedances. - Positive and zero sequence leakage impedances. - Neutral grounding details. (4) Capacitor data, for each Mvar supply bank. (5) Information about cables and lines. - Impedances R, Xl, Xc both positive and zero sequence, for each circuits of appreciable length. (6) Other power system elements. - Surge arresters: location and rating. - Grounding resistors(and reactors, if any): rating and impedance of each. - Series reactors: rating and impedance (7) Operating modes and procedures. - Sequnce for closing each circuit breaker. - Action of existing protection scheme during system over voltages and undervoltages. Switching Transient Problem Areas Switching of reactive equipment such as capacitors or inductive apparatus represents the greatest potential for creating excessive transients. Capacitors can store, trap and suddenly release relatively large quantities of energy. Simi larly, highly inductive apparatus possesses energy storage cabability which can release large quantities electromagnetic energy during a rapid current decrease. It means that the greater the energy storage in associated system elements, the greater transient magnitudes become. The following is a partial list of transient-related problems. (1) Energizing and deenergizing transients on lines or cables. vm(2) Switching surge response of motors, generators, transformers. (3) Optimum surge arrester location. (4) Switching of large-magnitude inductive currents. (5) Switching of capacitors. (6) Restrike phonemena in opening of lines, cables, and capacitor bank. (7) Transients in power electronic devices. (8) Switching surge reduction by means of controlled closing of circuit breaker or resistor pre-insertion. (9) Statistical distribution of switching surges. (10) Recovery voltages on tranmission system. Control of Switching Transients The philosopy of control of switching transients in power system revolves around: (1) Minimizing the number and severity of switching events. (2) Limitation of the rate of exchange which is important during transient pe riod. (3) Extraction of energy (4) Shifting of resonance points to avoid amplification offensive frequencies. (5) Provision of energy storage elements in order to release or trap energy within safe limits. (6) Provision of paths high-frequency currents. In order to carry out this philosopy, it has been proposed many ways in the literature practically. These are following; (1) Temporary insertion of resistances between circuit elements. For example, IXinsertion reistors in circuit breakers. (2) Series reactors. (3) Damping resistors in filter circuits and surge protective circuits. (4) Surge capacitors. (5) Filters. (6) Surge arresters. (7) Necessary switching only, with properly maintained switching devices. (8) Proper switching sequences. In this thesis, a general study has been done for transient switching phenom ena. In the second chapter, philosophy and fundamentals of transients events in the basic electric circuits. In this connection, in order to investigate behavior under transient conditions of basic R-L, R-C, R-L-C circuits which is supplied by either DC or AC source, their own differential equations have been builded. Some comments have been done by giving solutions of these equations without solving. In the third chapter, overvoltages in power systems have been classified as external overvoltages and internal overvoltages. Since external overvoltages are not taken place by switchings, it has been referred briefly. But internal over voltages arising from switching events have been classified between themselves properly, as steady-state internal overvoltages and transient internal overvolt ages. On the other hand in this chapter, some measurements about switching transients, which is accepted by IEC, has been given. In the fourth chapter, some events which causes to the transients in power system have been tackled with details. These are following; (1) Removing of a short circuit fault at the terminal of an unloaded generator. (2) Removing of a short circuit fault at the terminal of an unloaded transformer. (3) Analysis of three-phase short circuit faults by means of symetrical compo nents method. x(4) Out of phase (Asynchronous) switching (5) Transients arising from closing and reclosing in transmission lines and cables. (6) Transients arising from opening of unloaded transformer. (7) Transients taking place opening of unloaded transmission lines. (8) Switching surges as a results of switching events. (9) Short line or kilometric faults. Except out of these, in the section 4.6 a theoritical study for damping of transients. Furthermore, at the end of each section it has been tried to be stud ied some practical approaches in order to damp to the transient overvoltages. After fourth chapter, the thesis includes only analysis aids of transient events. In the fifth chapter, it has been tackled Transient Network Analyzer (TNA) The importance of TNA was referred at the beginning of summary sec tion. In this chapter, first components of TNA has been introduced. Then accuracy in TNA has been studied, After that it has been dwelled on studying procedure in TNA. Fnally, it has been given a study example about TNA. Sixth chapter, which is last one, is most original chapter in this study. As it has just referred at the beginning of summary section, digital computers have been commonly used in transient analysis since last decade, if some condition are convenient. There are a lot of digital computer program which has been written for this aim. On the other hand, since transients analysis means studying of R- L-C circuits in terms of transients, general-aim circuit analysis programs can be used on condition that representing of power system component with convenient models. Therefore, in this thesis a general-aim circuit analysis program called Pspice has been used. Pspice, which is prepared by Microsoft Company, runs not only for transient analysis, but also every analysis type in electric circuits such as steady-state analysis, D.C analysis, operating point analysis, Fourier analysis, etc. In order to analyze a circuit with Pspice, first step is to define the circuits with format of Pspice. Second step is to determine analysis type. Third step is to run program and obtain results. It has been referred to these subjects in the sixth chapter with details. At the same time, in the sixth chapter model of power system elements have been tackled, which are used digital computer solutions of transients. A gener ator model has been introduced. Since it was proved that using of complicated generator model is unnecessary in transient analysis in literature experimental, a simple model has been given about it. Transformers are devices which their xirepresentation is most difficult. Several models about them have been proposed since the beginning of the century. In this thesis, this models have been classified as lumped-parameter and distrubuted parameter model. But in the analysis, lumped-parameter model has been usually used. Transmission lines must be represented by distrubuted-parameter in order to obtain accuracy results. On the other hand, it has been referred that models of other auxiliary devices such as circuit breakers, series reactors, capacitor banks, filters and surge arresters. Consequently, since the greater voltage level in power systems, the greater internal transient over voltages become, switching events must be taken into account by designers. At the same time, solving of this problem requires a good engineering-knowledge in terms of designers, whether they make by hand or other auxiliary tools. If the problem is studied in terms of analysis aids, TNA seems more useful than digital computer, at present. But in the future digital computer will probably be more useful. Because digital computer is to introduce much more choices to the designers, even now, if representation of nonlinearity of some power system elements is not taken into account. In this connection, Pspice can be used as education-aim in the universities, even though it is unuseful for designing of power system. xn
Benzer Tezler
- EMPT ile enerji iletim sistemlerinde açma-kapama olayları analizleri
Switching phenomena analyses of power transmission systems with EMTP
TANER DENİZ
Yüksek Lisans
Türkçe
1995
Elektrik ve Elektronik Mühendisliğiİstanbul Teknik ÜniversitesiDOÇ.DR. ADNAN KAYPMAZ
- Designing a microgrid stabilizer using sliding mode controller
Kayan kipli denetleyici kullanarak mikro şebeke denetleyici tasarımı
HASAN MOUSAVİ SOMARİN
Yüksek Lisans
İngilizce
2016
Elektrik ve Elektronik Mühendisliğiİstanbul Teknik ÜniversitesiElektrik Mühendisliği Ana Bilim Dalı
DOÇ. DR. VEYSEL MURAT İSTEMİHAN GENÇ
- Yeni Cami'nin akustik açıdan performans değerlendirmesi
Evaluation of the acoustical performance of the New Mosque
EVREN YILDIRIM
Yüksek Lisans
Türkçe
2003
Mimarlıkİstanbul Teknik ÜniversitesiMimarlık Ana Bilim Dalı
PROF. DR. SEVTAP YILMAZ DEMİRKALE
- Avlulu bina biçiminin farklı iklim bölgelerinde iklimsel performansa göre optimizasyonu için geliştirilen bir yöntem
A method developed for optimization in view of climatic performance of the form of the courtyard buildings in regions of different climates
ENES YAŞA
- Condition monitoring and fault detection for electrical power systems using signal processing and machine learning techniques
Sı̇nyal ı̇şleme ve makı̇ne öğrenme teknı̇klerı̇ kullanılarak elektrı̇k güç sı̇stemleri ı̇çı̇n durum ı̇zleme ve arıza belirleme
YASMIN NASSER MOHAMED
Doktora
İngilizce
2024
Elektrik ve Elektronik Mühendisliğiİstanbul Teknik ÜniversitesiElektrik Mühendisliği Ana Bilim Dalı
PROF. DR. ŞAHİN SERHAT ŞEKER