Stefanos Delikaraoglou

Abstract: With the integration of fluctuating renewable production into the electricity system, electric drive vehicles may contribute to the resulting need for exibility if the market conditions provide sucient economic incentive. To investigate this, we consider the short-term management of electric vehicles in a market environment. From the perspective of vehicle operators participating in the electricity spot market, the problem is to optimally charge and discharge the vehicles in response to spot market prices. We consider the case of a vehicle owner who is a price-taker, and that of a eet operator who can inuence prices. In both cases, we show how the problem is amenable to dynamic programming with respectively linear or quadratic costs. With discretizations of the state space, however, the problem of eet operation is prone to suffer from the curse of dimensionality, and we therefore propose an ex ante vehicle aggregation approach. We illustrate the results in a Danish case study, and find that although optimal management of the vehicles does not allow for storage and day-to-day exibility in the electricity system, the market provides incentive for intra-day flexibility.

Abstract: The achievement of the national energy targets in Greece is mainly based on the exploitation of the abundant wind and solar potential. The effective implementation of these technologies into the Greek power system requires the determination of a long-term energy planning, which takes into account the characteristics of the existing power system and the availability of wind and solar resources into the current geographical area. Technical aspects related with the reliability of the Greek power system and its ability to absorb the variable output of wind and PV are analyzed. In such a perspective, an hour by hour simulation of the Greek power system provides the energy balance of the system and the renewable energy curtailment. A second probabilistic model is used to evaluate the effect of wind and PV integration on the reliability of the Greek power supply system through the calculation of the capacity credit. Both approaches contribute on the determination of the optimum mix between the two leader technologies. Results show that the simultaneous integration of wind energy and PV could have positive effects both on the reliability and on the renewable power absorption. Apart from that, the optimum mix requires a larger wind than PV integration, which in case of the Greek case study is accounted for at least 2:1 ratio, even if financial aspects are ignored.

Abstract: � αιολική ενέ�γεια α�ο�ελεί �ην �λέον ��ιμη �ε�νολογικά και οικονομικά αν�αγ�νι��ική �Π�. � ε�ί�ε�ξη ��ν �θνικ�ν �����ν για �ο 2020 �ε�νά �α��� μέ�α α�� �ο ��ί�μα �η� μεγαλ��ε�η� δ�να�ή� α�οδο�ική� εν��μά���η� ανεμογεννη��ι�ν ��ο ����ημα. � ����έ�ι�η ��ν ανεμολογικ�ν �α�ακ�η�ι��ικ�ν ��ι� �ε�ιο�έ� ανά���ξη� α�αι�εί �ην διε�ε�νη�η �ε�νικ�ν ζη�ημά��ν �ο� ��ε�ίζον�αι με �ην α�ο����η�η �η� αιολική� ενέ�γεια� και �ην �α�ο�ή εγγ�ημένη� ι���ο� και καθο�ίζο�ν �ην ενε�γειακή ��νει��ο�ά και �ην αξιο�ι��ία �ο� ηλεκ��ικο� ����ήμα�ο�. Σ�ην �α�ο��α ε�γα�ία, μελε�ά�αι η βέλ�ι��η ���οθέ�η�η ��ν αιολικ�ν εγκα�α��ά�ε�ν με ��ή�η γενε�ικ�ν αλγο�ίθμ�ν με ε�α�μογή �ε ��ία �ενά�ια εγκα�ε��ημένη� αιολική� ι���ο� 3000, 5000 και 8000MW. Χ�η�ιμο�οιο�ν�αι αν�ι��ο���ε��ικέ� ��ονο�ει�έ� ανεμολογικ�ν δεδομέν�ν για κάθε �ε�ιο�ή ενδια�έ�ον�ο� ανά �ην ε�ικ�ά�εια, οι ο�οίε� έ�ο�ν ��οκ��ει με ��ή�η �ο� ε�ι�ει�η�ιακο� με�οκλιμα�ικο� με�ε��ολογικο� ��ο���ο� COAMPS �ο� ανα����θηκε α�� �ο �μήμα �α��ική� �ε�ε��ολογία� �ο� ��γα��η�ίο� �αλα��ί�ν ��ε�ν�ν (Naval Research Laboratory) ��ν �Π�. Το ��ολογι��ικ� ε�γαλείο EASY �ο� ��γα��ή�ιο� �ε�μικ�ν Σ��οβιλομη�αν�ν �ο� ��Π, ��η�ιμο�οιεί�αι για �ον ��ο�διο�ι�μ� �η� γε�γ�α�ική� δια��ο�ά� ��ν αιολικ�ν με κ�ι�ή�ιο βελ�ι��ο�οίη�η� �ην μέγι��η ενε�γειακή ��νει��ο�ά ��ν αιολικ�ν και �ην μέγι��η �α�ο�ή εγγ�ημένη� ι���ο�. � αν�ικειμενική ��νά��η�η βελ�ι��ο�οίη�η� ��ολογίζε�αι με ��ή�η �ιθανο�ική� ανάλ��η� λαμβάνον�α� ����η �α δεδομένα �ο� ελληνικο� ηλεκ��ικο� ����ήμα�ο�, �ην ζή�η�η και �α �α�ακ�η�ι��ικά ��ν ��μβα�ικ�ν και �δ�οηλεκ��ικ�ν μονάδ�ν. Το ζη�ο�μενο είναι ο ��ο�διο�ι�μ�� �η� εγκα�ε��ημένη� αιολική� ι���ο� �ε 27 ��οε�ιλεγμένε� θέ�ει� �ο� καλ���ο�ν �ο ε����ε�ο μέ�ο� �ο� ελληνικο� γε�γ�α�ικο� ���ο�, και �ε�ιλαμβάνο�ν �ην η�ει���ική �λλάδα και �ο νη�ι��ικ� ���ο. Τα α�ο�ελέ�μα�α κα�αδεικν�ο�ν �ην �ημαν�ική ε�ίδ�α�η �η� γε�γ�α�ική� δια��ο�ά� ��ν αιολικ�ν εγκα�α��ά�ε�ν ��ον ��ν�ελε��ή εγγ�ημένη� ι���ο� και ��ην ενε�γειακή ��νει��ο�ά. ��ί�η�, α�� �ην ανάλ��η ��ν α�ο�ελε�μά��ν γίνε�αι �α�έ� ��ι �ημαν�ικ� ��οι�είο �ο� ��έ�ει να λη�θεί ����η ��ην ανά���ξη �η� αιολική� ενέ�γεια� είναι η ��ηλή ����έ�ι�η �ο� ανέμο� �ο� εμ�ανίζε�αι ��ην ε����ε�η γε�γ�α�ική �ε�ιο�ή �ο� �ιγαίο� και ��ν �α�άλι�ν �η� �να�ολική� η�ει���ική� �λλάδα�, με �ημαν�ική ε�ίδ�α�η ��ην �ε�ικο�ή αιολική� ενέ�γεια�, ��ην εγγ�ημένη ι��� και �ελικά ��ην ενε�γειακή ��νει��ο�ά.

Abstract: To meet the wind energy national targets, effective implementation of massive wind power installed capacity into the power supply system is required. In such a perspective, the wind capacity credit and the effective absorption of wind energy production are two of the most important technological issues. The effect of spatial dispersion of wind power installations within a very wide area (e.g. national level) on the two above mentioned issues should be accounted for. The whole approach is based on probability theory and makes use of wind forecasting models to represent the wind energy potential over any candidate area for future wind farm installations in the country. Additionally, the Generalized Evolutionary Algorithm EASY created in the laboratory of thermal turbomachines at NTUA, has been used to define the optimum solution of wind installed capacity in the several candidate macro-sites in the Greek power supply system. Results show that the spatial dispersion of wind power plants contributes beneficially to the wind capacity credit and the wind energy penetration levels into the power system.

Abstract: Predictability aspects are most often disregarded at the time of optimally spreading wind power capacities. The potential impact of predictability and of different types of forecast products are analysed here in various market environments, i.e. zonal markets which are most common in Europe and nodal markets as existing in the US. Methodologies for forecasting, optimal participation in electricity markets in view of price dynamics and forecast uncertainty, and finally for optimal investment, are described. Simulations based on realworld datasets and simplified power systems allow us to derive a number of findings supporting the interest of fully describing forecast uncertainty and spatio-temporal dynamics at the investment stage.

Abstract: The current work addresses the optimization of wind power investments in liberalized electricity market environments. A thorough description of the main components and market mechanisms of Nord Pool along with in depth discussion about the overall uncertainties related with this type of investment are presented. Furthermore, the necessary definitions about the different wind power forecasting methods and the description of a methodology for generating spatially correlated wind power scenarios are given. For the purpose of the current study real wind power measurements and the corresponding forecasts for the area of Western Denmark were utilized. Various bidding strategies were employed based on different types of wind power forecasts in order to assess the optimal deployment of a wind power portfolio in the zonal market framework of Nord Pool. In addition, a model for the simulation of an LMP-based market was established and the optimization of the capacity distribution over the buses of the power system was pursued for different portfolio sizes. The results of the application in the zonal market environment underlined the importance of advanced wind power forecasting methods that provide information about the whole predictive distributions when aiming at the performance ratio maximization. In addition, it was proven that the incorporation of the spatial interdependence of wind in the bidding strategy leads into wider geographical distribution of the capacity and thus it improves the overall profitability of the investment. The implementation of the investment optimization methodology in the LMP-based market structure revealed the effect of increased wind power penetration on the electricity prices of the day-ahead and real-time markets and consequently on the revenues of the market participant. Moreover, it was recognized that the optimal distribution of the wind power capacity does not rely only on the wind correlation patterns but it accounts also for the influence of the wind power on the LMPs.

Abstract: The main purpose of this diploma thesis is to contribute towards the effort of large scale integration of wind energy into the Greek power supply system. The main subjects examined and analyzed in this study relate to various parameters which are considered vital to the national energy planning process. The successful implementation steps towards an increased wind energy contribution into the energy mix of Greece require the accurate assessment of these parameters. Therefore, any effort aimed at this direction contributes, in one way or another, to the solution of the complex problems, which arise as we proceed to a new model of sustainable development, which will be largely based on the reliable and efficient integration of the Renewable Energy Sources (RES) into the electric system of our country. The content of the study has been divided into seven chapters. The first chapter provides a description of the disadvantages of the current energy model, analyses the benefits which could follow the integration of RES into the energy mix and presents the most important steps towards this target. The second chapter is dedicated to the role of wind energy into the global energy market, mentioning some basic facts about the up to date evolution of this technology in the European and global energy scenes. In addition, this chapter presents several representative scenarios concerning the future development of wind energy and the most important benefits that could result from the usage of this technology, both for the local and global community. The third chapter describes analytically the methodology for the calculation of the capacity credit using probability analysis. The fourth chapter deals with the definition of the optimum solution of wind installed capacity in several candidate macro-sites in the Greek power supply system, using the optimization method of evolutionary algorithms. The fifth chapter presents an analysis of the impacts and consequences which are likely to result from the integration of photovoltaic panels in different electric system types. Furthermore, a study is conducted focusing on the definition of the optimum ratio between photovoltaic and wind energy installations in order to achieve maximum capacity credit for each of the power supply systems under consideration. In the sixth chapter, a methodology about the simulation of the operation of the Greek interconnected power supply system is described and the results of this process, for different levels of wind energy penetration, are presented. Finally, the seventh chapter concludes with an overall synopsis of the results from all the aforementioned topics and provides some recommendations for further research in the field of large scale integration of wind energy.