Bayesyen oyun yaklaşımı ile elektrik enerjisinde talep tarafı yönetimi: Üç tüketicili bir tesis örneği
Power demand side management using bayesian game approach:A case with three consumers
Yazar: ZEYNEP BEKTAŞ
Danışman: DOÇ. DR. GÜLGÜN KAYAKUTLU
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Endüstri Mühendisliği Ana Bilim Dalı / Endüstri Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2015
Konu: Endüstri ve Endüstri Mühendisliği = Industrial and Industrial Engineering
Dizin: Enerji optimizasyon modeli = Energy optimization model

Özet:
Teknolojik gelişmelerin düzeyinin, enerjinin kullanım biçimlerine etkisi büyüktür. Elektronik cihazların hayatın her alanında giderek daha büyük bir yer tutması, elektrik enerjisinin kullanım payını oldukça arttırmıştır. Üretim, iletim, dağıtım ve tüketim olmak üzere dört temel süreçten geçen elektrik enerjisinin optimal biçimde kullanılması problemi, on yıllardır gündemdedir. Son 30 yıldır ise, bu optimizasyon çalışmaları tüketim süreçlerini de içine almaktadır. Arzın karşısındaki en önemli aktör olan talep tarafının kontrol edilmesi fikriyle ortaya çıkan bu yaklaşım, Talep Tarafı Yönetimi (TTY) olarak adlandırılır. TTY ile tüketicinin faaliyetlerini olumsuz etkilemeden, elektrik talebinin daha dengeli bir hale getirilmesi amaçlanır.
Gelişmiş ülkelerde TTY programlarının en büyük destekçisi akıllı elektrik şebekeleridir. Güç üretici ve tüketicileri arasında çift yönlü iletişimi mümkün kılan bu sistemler, talebin yönetimi çalışmalarına da yeni bir boyut getirmiştir. Akıllı şebekelerin mevcut olmadığı sistemlerde ise, uygulanabilecek TTY programları sınırlı kalmaktadır. Bu çalışma ile, TTY programlarının sınırları gevşetilmek istenmiştir. Eksik bilgi durumlarını modellemekte kullanılan Bayesyen oyunlar ile, şebekedeki haberleşme eksikliğinin giderilmesi amaçlanmıştır.
Elektriği tek bir kanaldan alan tüketici gruplarının saatlik elektrik taleplerinin dengesizliği, şebeke kararsızlığını olumsuz etkilemektedir. Böyle sistemler için, saatler arası talep farklılıklarını minimize etmeyi amaçlayan bir doğrusal olmayan karışık tam sayılı programlama modeli önerilmiştir. Sanayi kullanıcıları dikkate alınarak kurulan modellerde, işletmelerin üretim planları da kısıt olarak bulunmaktadır. Sonraki aşamada ise, hem gruptaki tüketicilerin her birini hem de toplam değerleri göz önüne alıp şebeke kararsızlığına olan etkiyi negatif fayda fonksiyonu olarak kullanan bir Bayesyen oyun modeli kurulmuştur. Önerilen bu iki aşamalı yöntem ile, ortak optimalliği sağlayacak günlük elektrik tüketim çizelgelerinin belirlenmesi hedeflenmektedir.
Uygulama çalışması üç sanayi tüketicisinden oluşan bir tesiste yapılmıştır. Her bir tüketici için karışık tam sayılı modeller çözüldükten sonra, üç oyunculu Bayesyen oyunun tüm verileri elde edilmiştir. Ardından oyun çözülüp, Bayesyen Nash denge noktasına ulaşılmıştır. Denge noktası, her bir oyuncunun kullanması gereken tüketim çizelgesini verir. Oyuncular bu elektrik tüketim çizelgelerini uyguladıklarında, hem şebeke kararsızlığında azalma elde edilmiş hem de buna paralel olarak elektrik tüketim maliyetleri düşürülmüştür. Ayrıca Nash teoremini doğrular biçimde, oyunculardan herhangi birinin farklı bir çizelge kullanması durumunda daha fazla fayda sağlayamayacağı da görülmüştür.

Abstract:
The impacts of technological development level to the ways of energy usage are great. Due to the higher usage of electronic devices in every area of life, the share of electrical energy usage has increased substantially. Electrical energy includes four basic processes, i.e., generation, transmission, distribution and consumption. Optimal usage of electrical energy problem is on the agenda for decades. In the last 30 years, these optimization studies comprehend consumption process as well. The approach which is based on the control of demand side, the most important second actor, is referred as Demand Side Management (DSM). The aim of DSM is to manage electricity demand without affecting consumers' activities adversely.
Demand management programs can be divided into two topics: energy efficiency and load management. In energy efficiency studies, consumption is reduced without changing consumers' welfare. On the other hand, in load management studies, hourly load flows are regulated purposefully without changing consumption. The main objectives of these studies are to reduce grid instability, and to provide balanced load demand which is the most important desire of the supply side. Amount of the contribution to grid stability can be seen from daily load curves. The aim is to flatten the load curves with DSM studies.
The largest supporters of DSM programs in developed countries are smart grids. They brought a new dimension to the demand management studies by enabling two way digital communication between power producers and consumers. In the absence of smart grid systems, applicable DSM programs are limited. Although the usage of smart meters becomes more popular nowadays in our country, as a whole, there is not a smart grid infrastructure yet. Existing smart meters can only hold consumption data that has time dimension.
Price-based DSM is the one on which consumers are most active. The programs which are routed to directly control the customer consumptions by using incentives and penalty payments are supported by different pricing tariff applications. These pricing tariffs can be analyzed under three groups named static, dynamic and real time. These require more advanced grid infrastructure, respectively. The one which is used in our country is static, in other words, time of use tariffs. Time of use tariffs may be one-time period or multiple-time period.
The aim of this study is to loosen the limits of the DSM program when two way digital communication in electrical network is not possible. With Bayesian games, which is used to model games with incomplete information, it is intended to overcome the lack of communication in the network. Bayesian game is based on the update of belief functions with Bayesian theorem when there exist incomplete information about the players or information cannot be shared. Besides, different from other games, in these kind of games, there exists 'type' concept. This can be seen as a component reflecting a player's decision. In Bayesian games, equilibrium point is called as Bayesian Nash equilibrium and as in other games; in Bayesian games there is at least one Bayesian Nash equilibrium if types and actions of players are finite.
Grid instability is adversely affected by hourly demand imbalance of consumer groups that take electricity from a single channel. For such systems, a mixed integer nonlinear programming model is proposed to minimize the hourly demand differences. In the model, a nonlinear objective function is used which reflects the consumption amount differences of three-time period tariffs proportionally that are used in our country. Furthermore, another objective function is proposed for the cases where different tariffs are used. In addition, in the models where industrial users are taken into account, when total consumption is given as constant, enterprises' production plans are constrained.
The model proposed in this study is solved by using GAMS software. However, the outputs taken from this model are not the optimum results of this study but they reflect the all results that are in the feasible area. After feasible consumption schedules are set for each consumer, they are transmitted to a central control unit that is outside the consumers and the game model will be applied here. Each of the resulting feasible schedules will refer to the types of players in the game.
After obtaining all the components of Bayesian game, a Bayesian game model that uses payoff function is constructed that takes into account each consumers in the group as well as the whole. The payoff function is composed of the indicators that are goal functions of mixed integer programming models, but the indicators are used with negative coefficients not to destroy utility maximization principle. With this proposed two-step method, daily electrical consumption schedule is aimed that provides common optimality. When the game's equilibrium point is determined, according to the corresponding schedules, for each consumer, how much electricity consumed for each hour will be determined and the consumers will use devices in accordance with this order.
Application study is conducted in a facility consisting of three industrial consumers. For each customer, mixed integer models are created and these models are solved with GAMS software. The outputs of this model are seen as the inputs of the model of the next step. For each consumer different numbers of types are found. As the next step, with the help of Microsoft Excel program, game model is solved and Bayesian Nash equilibrium point is reached. Each player has seen the need to implement which consumption schedule for the purpose of common optimality. In accordance with Nash Theorem, it is seen that if any player use different schedules, they cannot provide a higher utility level.
Past consumption data that reflects the current status of the facility studied is created with simulation. To determine the combinations of machine usage in the factories, macros in Excel is used in this stage. When the consumption schedules gathered as a result of the method are compared with the historical data, a reduction in the power consumption costs as well as a reduction in grid stability is observed. The contribution to grid stability is shown by comparing load curves of the old and new situation.
Without violating existing production plans of the sampled factories and without changing total daily energy consumption, for each consumer and for factories as a whole, most balanced power consumption schedules are determined. Thus, grid instability originate from the factories is minimized and hence the purpose of the study is realized. Last but not least, proposed method's applicable areas and improvable points for the proposed study are discussed and proposals are offered.