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Load Management and Demand Response in Small and Medium Data Centers

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Load Management and Demand Response in Small and Medium Data Centers Thiago Lara Vasques Load Management and Demand Response in Small and Medium Data Centers PhD Thesis in Sustainable Energy Systems, supervised by Professor Pedro Manuel Soares Moura, submitted to the Department of Mechanical Engineering, Faculty of Sciences and Technology of the University of Coimbra May 2018 Load Management and Demand Response in Small and Medium Data Centers by Thiago Lara Vasques PhD Thesis in Sustainable Energy Systems in the framework of the Energy for Sustainability Initiative of the University of Coimbra and MIT Portugal Program, submitted to the Department of Mechanical Engineering, Faculty of Sciences and Technology of the University of Coimbra Thesis Supervisor Professor Pedro Manuel Soares Moura Department of Electrical and Computers Engineering, University of Coimbra May 2018 This thesis has been developed under the Energy for Sustainability Initiative of the University of Coimbra and been supported by CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brazil). ACKNOWLEDGEMENTS First and foremost, I would like to thank God for coming to the conclusion of this work with health, courage, perseverance and above all, with a miraculous amount of love that surrounds and graces me. The work of this thesis has also the direct and indirect contribution of many people, who I feel honored to thank. I would like to express my gratitude to my supervisor, Professor Pedro Manuel Soares Moura, for his generosity in opening the doors of the University of Coimbra by giving me the possibility of his orientation when I was a stranger. Subsequently, by his teachings, guidance and support in difficult times. You, Professor, inspire me with your humbleness given the knowledge you possess. A formal acknowledgement is also due to Institute of Systems and Robotics of the University of Coimbra (ISR-UC), Energy for Sustainability Initiative, MIT Portugal Program and specially to Federal University of Goiás and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brazil (CAPES), for their support, which allowed me pursuing my Ph.D. I am deeply thankful to my wife, who besides loving me all the time, has been my Ph.D. companion in this adventure that was to leave our country and live abroad changing our lives completely. Her encouragement in difficult periods, fruitful discussions and invaluable advices, allowed me to move forward in some stages of the Ph.D study. I love you! I am very grateful to my family for their love, support and sacrifices by the time away and full of homesickness; to my parents, who always believed in me and invested all their energies in my education; to my brothers, who are my pride for being exactly who they are; to my niece, who renewed my days with a love that I did not know; to my sisters-in-law for the love and support; to the family of my wife, who is now my family and has been so precious; and to all my relatives, who allowed me to be away, but always near. I owe a great debt of gratitude to the family that I built in Portugal, this country that is in my heart now. To the countless and unforgettable moments of love spent in paradise, at Quinta do Outeiro, beside my Mindinha, who is my Portuguese mother, my Portuguese and inspiring brother Miguel, my dear Juliana and my real squiggly Lana; to my Ph.D colleagues, who became my beloved friends in this journey, Lurian and Zuleika. Every moment we uniquely shared together will be deeply kept in my heart; to Joanna, Merielly and Kika Maria, my dear friends from Porto, who have given me so many moments of joy and happiness; to Francisco and Ruben, our dear friends from Lisbon, who have always treated me with the best of Portugal; to special meetings, with special people, who crossed my path in Portugal. I would like to also thank all colleagues and professors from DEEC and DEM of FCTUC, and I want to express a special gratitude for the valuable help offered by dear Thiago Luz. Finally, I would like to thank Coimbra and Portugal for the unforgettable days I spent knowing, living and feeling the best of this wonderful country. ABSTRACT Data centers are the backbone of a growing number of activities in modern economies. However, the large increase of digital content, big data, e-commerce, and Internet traffic is also making data centers one of the fastest-growing users of electricity. The total energy consumption of data centers corresponded to almost 1.5% of the global electricity consumption and has an approximated annual growth rate of 4.3%. Therefore, it is very important to increase the energy efficiency in data centers with actions such as power usage management, server consolidation, energy efficient components and systems, as well as demand response programs and renewable energy sources. Small and medium data centers account for more than 50% of the total electricity consumption in this sector. In fact, surveys indicate that this data center profile waste more energy than larger facilities. Nevertheless, existing studies tend to be focused on the energy related issues for large data centers rather than small and medium data centers. Thus, this work aims to present how an intensive energy consumer, such as small and medium data centers, can become more efficient from the energy point of view and how they can take advantage of demand response programs to decrease costs and to cooperate with the grid to ensure higher reliability and sustainable development goals. For this purpose, a set of actions have been taken in pursuit of this objective. Firstly, a meticulous state-of-the-art literature review of data centers energy efficiency and demand response perspectives was performed, providing fundamental information about the complex and technological world of small and medium data centers, in order to support the knowledge of their flexible load. An energy efficiency survey directed at Brazil, Portugal and the United States was also conducted, showing an alarming reality regarding energy efficiency practices within small and medium data centers. In the same context, an impact and potential assessment on energy efficiency towards small and medium data centers was performed allowing to observe the main advantages, disadvantages and applications in three important methodologies. A design of load management strategies and opportunities for demand response was developed considering a framework with two layers encompassing an energy efficiency methodology, the management of flexibility and the deployment of demand response scenarios with dynamic tariffs or an incentive-based contract. Alongside, the small and medium data centers load mathematical modeling and specification of optimization processes were provided within the same scope with two algorithms implemented with different approaches; one focused on small and medium data centers operators, and other dedicated to distribution system operators. At the data center level, a mixed-integer linear programming optimization technique is used to control flexible loads (considering ICT workload, cooling and UPS), in order to reduce the cost function in a price-based outline or to match the load reduction requirements in an incentive-based outline. Concerning the distribution system operator, a random-rotation and fairness algorithm selects the data centers to be used in each demand response event. Such algorithm deals with small and medium data centers in an aggregated and equitable way by drawing on their joint and flexible loads in contractual terms, as if they were one large data center. Finally, the optimization results were firstly demonstrated in a small and medium data centers perspective, as well as their respective scenarios, in which it has been proven the algorithm operation and reliability. The potential for cost savings in demand response was also proved, being achieved with the considered incentives in the simulation process, savings of 1.33% for small and 5.15% for medium data centers in the incentive approach, and 0.21% for small and 0.68% medium data centers in the dynamic tariff approach. Subsequently, the same premises were utilized with focus on the distribution system operator point of view, enabling to predict specific contractual policies that can be adopted in this type of relationship through the best and the worst scenarios simulations. The scenario with a preponderance of incentives stimulates the adoption of demand response programs applied to small and medium data centers, nevertheless the unchanged and penalty cases enable to forecast an unfavorable scenario for this sort of demand response program. In this context, on one hand, the one single day analysis showed a variation in the reduction potential between 18.02% and 91.16%, while the highest value in the penalty profile was 356 € and in the incentive profile 10,580 €. The 22 business day analyses presented a fluctuation in the reduction potential in the range of 13.12% and 71.38%, whilst the highest value in the penalty profile was 1,200 € and in the incentive profile 84,700 €. Keywords: Data Centers, Information and Communication Technologies, Energy Efficiency, Load Management, Demand Response RESUMO Os centros de dados são a base de um número crescente de atividades na economia moderna. No entanto, o grande aumento de conteúdo digital, big data, comércio eletrónico e tráfego da Internet está a tornar os centros de dados um dos utilizadores de eletricidade com um crescimento mais acentuado, com um consumo de energia correspondente a quase 1,5% do consumo global e com uma taxa de crescimento anual de aproximadamente 4,3%. Portanto, é de extrema importância aumentar as iniciativas de eficiência energética em centros de dados, direcionadas para a gestão do uso de energia, a consolidação de servidores, utilização de componentes e sistemas energeticamente eficientes, bem como a adoção de programas de resposta da procura e a utilização de fontes de energia renováveis.
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