Çift devre üç fazlı bir sistemin altı fazlı çalışması durumunda işletme büyüklükleri üzerine etkilerinin incelenmesi
A General investigation of the six-phase transmission system operation effects compared to lthe double-circuit three-phase transmission system
- Tez No: 19430
- Danışmanlar: PROF.DR. H. NUSRET YÜKSELER
- Tez Türü: Yüksek Lisans
- Konular: Elektrik ve Elektronik Mühendisliği, Electrical and Electronics Engineering
- Anahtar Kelimeler: Altı fazlı enerji sistemi, Arıza analizi, Enerji iletim sistemleri, Üç fazlı enerji sistemi, Six phase energy system, Fault analysis, Energy transmission systems, Three phase energy system
- Yıl: 1990
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: Belirtilmemiş.
Özet
ÖZET Sürekli artan yük talebi karşısında santrallardan yük merkezlerine çok daha fazla enerji iletmek gerekmektedir. Enerji iletim hatlarının kapasitesinin artırılmasının en genel çözümü olan gerilim kademesinin yükseltilmesi bugün doyma noktasına ulaşmıştır. Bu durum karşısında geleneksel üç-fazlı enerji iletimi yerine hattın iletim kabiliyetini % 73 oranında artıran altı-fazlı enerji iletimi alternatif olarak ortaya çıkmaktadır. Enerji iletim sistemlerinin işletilmesi ve planlanması kısa devre çalışma analizlerini zorunlu kılmaktadır. Bu analizler olası arıza tipleri için yapılarak devre kesicilerinin seçimi, koruma biçim ve ayarı bu analiz sonuçlarına göre yapılır. Bu çalışmada 380 kV gerilim kademesindeki üç- fazlı çift devre enerji iletim sistemi yine aynı gerilim kademesinde altı-fazlı enerji iletim sistemine dönüştürülerek incelenmiştir. Altı-fazlı enerji siste minin torn haralarında altı-faz için olası kısa devre analizleri yapılmıştır. Güncel durumu ve gelecek durumu karakterize eden iki konum ele alınmış ve bilgi sayar ile yapılan çalışma sonucunda değişik tipteki arızalar için bulunan bara kısa devre akımları karşı laştırılarak sistemin tanınmasına çalışılmıştır.
Özet (Çeviri)
SUMMARY A GENERAL INVESTIGATION OF THE SIX-PHASE TRANSMISSION SYSTEM OPERATION EFFECTS COMPARED TO THE DOUBLE-CIRCUIT THREE-PHASE TRANSMISSION SYSTEM. Because of ever increasing load demands, electric utilities are facing the pressing need to transfer more and more power from generation stations to load centers. The most common solution of increasing power transmission voltages seems to have reached the point of saturation. Recently the concept of high phase order transmission (HPOT) was pioneered in place of conventional three-phase power systems. HPOT utilities difficult to obtain rights-of-way in a better manner, and offers a very appealing and unique solution to the problem of increased demand of electric energy. At present, the six-phase transmission system appears to be the most promising amont HPOT systems. Fault studies form an important step in the design of adequate protective schemes. A detailed fault analysis programme employs symmetrical or Clarke's component transformation for six and higher phase systems have been arrived purely be anoloyy and intuitive reasoning. The various faults likely to occur on a six- phase system may be as large as eleven in number, compared with only five in the case of three-phase systems. Six-phase faults are the most severe and least common, whereas single-line-to-ground faults are least severe but most common. In addition, faults involving two and three phases with several distinct possibilities may be more frequent in six-phase systems than in three-plase systems. The various types of faults that can occur in a six-phase system, which is considered here, are : i) single-phase-to-ground fault (LG) ii) two-phase-to-ground fault (LLG) iii) two-phase falut (LL) iv) three-phase-to-ground fault (LLLG) VIv) three-phase fault (LLL) vi) four-phase-to-ground fault (LLLLG) vii) four-^phase fault { LLLL) viii) five-phase-to-ground fault (LLLLLG) ix) five-phase fault (LLLLL) x) six-phase-to-ground fault (LLLLLLG) xi) six-phase fault (LLLLLL) In the development to follow, the six-phase system is assumed to be a balanced and unloaded, i.e. open- circuited during the prefault stage, and all faults are assumed to be bolted to simplify matters for clarity of presentation. To carry out the fault analysis of multi-phase systems generalised schemes using transformation as well as phase coordinate techniques are employed. The symmetrical component transformation method for three-phase systems employing the bus impedance description of the network is generalised to six-phase systems or the systems represented on an equivalent six-phase basis. The expression for fault currents at a six-phase bus 'k' involving a fault impedance/admittance matrix Zp / Y is given by (5), (6) in Table 1. Jk(F) = (ZF + ZKK) EK(0) (1) ^(P)“ 4 <”6 + zkk*?>~1eM0, (2) The fault voltages are given by Eur, - 4 <4 + 4»“X(0) »> Ek(F) = (u + zkkV Ek(0) (4) and other buses g(F) ”*-i(0) " ^ik^ktF) i = 1,2, N; i - k viaTABLE 1 : Fault impedance and admittance matrices, Type of fault Fault admittance/impedance matrix a b c d e £ 0 0 0 0 0 S(F) 111111 111111 111111 1 İ 1 1 1 1 111111 1 1 1 1 J 1 = ı/z, aai z6 The following steps are required to carry out the fault analysis : i) Perform the equivalent single-phase load flow analysis to determine the prefault voltages. ii) Form the sequence component bus impedence matrices. iii) Calculate the sequence component fault impedance/ admittance matrices. iv) Determine the fault current. v) Calculate the post-fault voltages, currents and power flows in the network as usual. The method of phase coordinates is a very powerful and flexible tool for fault analysis, especially where the transformation techniques become unwieldy or too cumbersome to apply. Moreover, all types of serres, shunt and simultaneous faults can be analysed with the same ease as for a single balanced fault. The basic steps required are as follows : vmi) The base-cas matrix Y is modified to Y ' to incorporate the machine and load representations. All static loads are converted to equivalent admittances and are added to the respective diagonal terms of Y. With these changes, the performance of the system is described by : Y'V = I' (5) ii) The solution of various faults is obtained by solving (5) with suitable constraints. The complexity of fault analysis in a six-phase system is much greated than in three-phase systems. The fact that there are six phases, each subjected to a different voltage, and a number of fault types much greater for the six-phase system. Keban - Gölbaşı line, 380 kV three-phase double circuit which is converted to 380 kV six-phase line, then the fault types that could arise in a six-phase system is calculated at the state of two different circuit types. And also the sequence network connection for each case is given. The fault currents on the buses are compared each other, and some graphs and tables are given for this purpose. IX
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