Rüzgar türbinlerinin şebekeye entegrasyonu ve performanslarının incelenmesi
Investigation of integration and performance of wind turbines into grid
Yazar: AHMET DABAKOĞLU
Danışman: DOÇ. DR. RAMAZAN ÇAĞLAR
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Elektrik Mühendisliği Ana Bilim Dalı
Derece: Yüksek Lisans, 2017
Konu: Elektrik ve Elektronik Mühendisliği = Electrical and Electronics Engineering

Özet:
Yenilenebilir enerji kaynaklarının elektrik enerjisi üretiminde kullanılması, fosil yakıt tüketimlerinin artması ve dünya nüfusunun hızla çoğalması nedeniyle günümüzde oldukça yaygınlaşmıştır. Rüzgar gücüne dayalı elektrik sistemleri bu ihtiyacı karşılama yolunda hızla gelişmiş ve büyük önem kazanmaya başlamıştır. Öncelikle rüzgar enerjisinden elektrik üretmenin avantaj ve dezavantajları, rüzgar enerjisinin Türkiye ve Dünyadaki genel durumu hakkında irdelenecek, ardından rüzgar türbinleri ile elektrik üretimi başlığı altında rüzgar enerjisi, rüzgar türbini tasarımları ve parçaları, kullanılan generatör tipleri ve özellikleri, gerilim kararlılığı sağlanması ve rüzgar enerjisinden elektrik üretme tekniği hakkında bilgi verilecektir. Rüzgârdan çok değişken biçimde elektrik enerjisi üretilmesi nedeniyle, büyük güçlerdeki rüzgar çiftliklerinin şebekeye entegrasyonu beraberinde çeşitli elektrik kalite problemleri de getirebilmektedir. Şebekeye bağlı rüzgâr türbinlerinin sayısının artması elektrik sisteminde gerilim kararsızlığı, reaktif güç ve frekans kontrolündeki zorluklar elektrik kalitesi problemlerini beraberinde getirmektedir. Şebekeye bağlı rüzgar sistemlerinin bölgesel ve sistem üzerinde olan bozucu etkileri, büyük rüzgar santrallerinin planlanmasında yaşanabilecek sorunlar hakkında bilgiler üçüncü bölümde verilmiştir. Bahsedilen elektrik kalite problemleri ve bunların ölçümleri incelenmiş, elektrik piyasası şebeke yönetmeliğine göre, şebekeye bağlı rüzgar türbinlerinin için reaktif güç, aktif güç, frekans değişimlerine bağlı toleransları, ayrıca gerilim düşümü, fliker ve harmonik sınırlamaları değerlendirilmiştir. 
Son bölümde rüzgar türbini sistemlerinde en çok kullanılan SKAG ve ÇBAG bağlı rüzgar türbini sistemleri incelenmiştir. SKAG ve ÇBAG bağlı rüzgâr türbinleri modelleri MATLAB- Simulink programıyla geliştirilerek farklı rüzgâr hızları için simule edilerek rüzgâr çiftliği kurulurken hangi rüzgâr türbin topolojisinin değişken rüzgâr hızlı sisteme daha uygun olduğu incelenmiştir. Geliştirilen benzetim sistemlerinde iki rüzgar türbini modelinin farklı seviyelerdeki rüzgar değişikliklerine verdikleri tepkiler, harcadıkları reaktif güç miktarı, ortak bağlantı noktasındaki gerilim kararlılığına etkilerini gösteren simülasyon yapılmıştır. Bunun yanında iki benzetim sistemi için tek-faz toprak, üç faz ve faz-faz kısa devre arızası durumlarında türbinlerin verdiği tepkiler ölçülerek, hangi generatörün bağlı bulunduğu benzetim sisteminin elektrik kalitesi üzerinde daha olumlu sonuçlar doğurduğu incelenmiştir. Yapılan benzetim çalışmalarının ardından varılan analizler ve sonuçlar, şekiller halinde sunulmuştur.

Abstract:
The use of renewable energy sources in the production of electric power has become widespread due to the increase of fossil fuel consumption and the rapidly increasing of the world population. Electrical power systems based on wind power are rapidly developing and gaining great importance in meeting this need. First of all, the advantages and disadvantages of electricity generation from the wind energy will be explored about the general situation of the wind energy in Turkey and the world, followed by the wind turbines and the power generation under the power production, the wind turbine designs and components, the generator types and features used, the voltage stability and electricity generation from wind energy information about the technique will be given. Due to the very different forms of electrical energy generated from wind, the integration of large wind farms into the grid can also bring various electrical quality problems. Today, most international network regulations require power quality requirements. The wind at the connection point for a given type of wind turbine can cause the farm to be limited in capacity. In addition, it is permissible to build lines with higher capacities with converters having better power quality characteristics. Information about the regional and systematic disruptive effects of the grid-connected systems, and the problems in planning the grid plants are given in the third section. The electrical quality problem and its implications are examined, the reactive power, the tolerances related to the frequency changes, voltage drop, the flicker and the harmonic limitations are evaluated according to the electricity market grid code. 
In the last section, the systems of wind turbines and SFIG and DFIG connected wind turbine systems have been investigated. SFIG and DFIG connected wind turbines models are simulated for different wind speeds that can be developed with MATLAB- Simulink program, for finding which wind turbine topology is more suitable for variable wind speed system when the wind farm is established. In the developed simulations, the two wind turbine models were simulated to show the responses of different levels of wind change, the amount of reactive power, the voltage stability at the point of common coupling. Electrical quality problems caused by wind power plants were investigated in this study for variable wind speeds single phase-earth, three-phase-earth and phase-phase short circuit faults made by SFIG and DFIG generator types commonly used in the market were investigated by comparison with simulation studies. A network connection criterion analysis was made in the DFIG connected wind farm; The behavior of the wind farm and the high voltage line to which the wind farm is connected has been examined while the short circuit power of the bus to be connected is 5%, 10%, 20%. SFIG and DFIG connected wind turbines models were developed with MATLAB- Simulink program and simulated for different wind speeds so that which wind turbine topology is more suitable for variable wind speed system when the wind farm is established. 
In the developed model, the two wind turbine models were simulated to show the responses to different wind speed changes, the amount of reactive power consumed, the voltage stability at the common connection point, and therefore the power quality effects, the amount of active power delivered to the network in wind conditions. The simulations followed by the calculations are analyzed and the results are folded.
For variable wind speed models in modern wind turbines, it has been found that the DFIG-connected wind turbine systems offer several advantages over the SFIG-connected wind turbine systems. At three levels of wind speed changes, such as cut-in, nominal wind speed and cut-off speed, it was observed that the DFIG-connected wind turbine was superior to the SFIG-connected wind turbine at the point of active power and voltage stability. At the same time, the amount of reactive power consumed was less in the turbines connected to the DFIG. All these factors should be taken into consideration when deciding which wind farm model should be set up.
According to these simulation results, the wind turbine systems with SFIG reach the nominal active power value faster than the wind turbine systems containing the DFIG. Even if the wind speed is constant, the rotor speed increases with time in the wind turbines containing the DFIG.
If the pitch angle values are compared within the two topologies in graphs at speeds of 9-14 m/s, wind turbine systems with DFIG provide simple and cost-effective power control with simple pitch angle control systems. At high wind speeds, the pitch controller maintains the wind turbine by limiting the maximum output power, while the pitch angle remains constant at low wind speeds. This flexibility provided by DFIG at variable wind speeds reduces the mechanical stress due to the wind speed on the wings of the wind turbine, thus reducing the vibration in the generated torque and thus reducing my electric quality problems like flicker.
In a SFIG full-scale power converter connected to a stator, the variable wind speed can be used in fast systems so that the total output power will remain around 1 pu, but this will lead to increased transmission and switching losses at the same time. In addition, due to the reactive power generating and consuming feature provided by the power electronic converters of DFIG technology, there is no need to connect the STATCOM to the capacitor groups as in the SFIG model, thus the system cost is reduced.
Compared with the simulation results, it can be said that with the appropriate converters and control systems, the DFIG connected turbines are more reliable and stable than the SFIG connected turbines.
Wind power plants, turbine, generator and control systems are developing day by day, and new wind turbine models can be developed as a result of future developments. On the other hand, studies on the network effects can be made as a result of different types of power generation plants working together. As a result, the parallel operation of the wind power plant should not impair the quality of the electricity supplied to other consumers. In Turkey, as the number of power plants that produce wind power increases, their connection with the grid will become increasingly important and the work to be done in this regard will increase even more.