| 1. |
- Henfridsson, Urban, et al.
(författare)
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Wave energy potential in the Baltic Sea and the Danish part of the North Sea, with reflections on the Skagerrak
- 2007
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Ingår i: Renewable energy. - : Elsevier BV. - 0960-1481 .- 1879-0682. ; 32:12, s. 2069-2084
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Tidskriftsartikel (refereegranskat)abstract
- Wave power, along with renewable energy-generating sources like tides and streams, is underestimated considering its advantageous physical properties and predictability. This paper examines possible examples of wave power installations in the Baltic Sea and the Danish part of the North Sea. Hindcasting data is used allowing estimations of wave energy generated and results show promising areas in the North Sea, but also several parts of the Baltic Sea are of interest. The study is based upon linear generator technique, placed on the seabed using point-absorbers arranged in arrays of up to several thousand units. The study aims at showing the physical possibilities of wave energy, including economical feasibility and environmental advantages of wave energy even in moderate wave climates. With discussion from two examples in the Baltic Sea, one in the Danish North Sea and a new pilot study site in the Swedish part of Skagerrak, this study show feasible illustrations of wave energy takeouts. Project examples vary in size due to distance to grid, grid voltage, and may thus be economically feasible. Examples also show considerations in societal and nature conservation matters, including aspects such as industrial and military interests, archaeological or marine reserves and local geology. The authors conclude that wave energy electric conversion is an option that needs more attention and which has several advantages compared to conventional renewable sources. Sound engineering, in combination with producer, consumer and broad societal perspective is advised for a sustainable development of wave energy conversion.
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| 2. |
- Neimane, Viktoria, 1971-
(författare)
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On Development Planning of Electricity Distribution Networks
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Future development of electric power systems must pursue anumber of different goals. The power system should beeconomically efficient, it should provide reliable energysupply and should not damage the environment. At the same time,operation and development of the system is influenced by avariety of uncertain and random factors. The planner attemptsto find the best strategy from a large number of possiblealternatives. Thus, the complexity of the problems related topower systems planning is mainly caused by presence of multipleobjectives, uncertain information and large number ofvariables. This dissertation is devoted to consideration of themethods for development planning of a certain subsystem, i.e.the distribution network.The dissertation first tries to formulate the networkplanning problem in general form in terms of Bayesian DecisionTheory. However, the difficulties associated with formulationof the utility functions make it almost impossible to apply theBayesian approach directly. Moreover, when approaching theproblem applying different methods it is important to considerthe concave character of the utility function. Thisconsideration directly leads to the multi-criteria formulationof the problem, since the decision is motivated not only by theexpected value of revenues (or losses), but also by theassociated risks. The conclusion is made that the difficultiescaused by the tremendous complexity of the problem can beovercome either by introducing a number of simplifications,leading to the considerable loss in precision or applyingmethods based on modifications of Monte-Carlo or fuzzyarithmetic and Genetic Algorithms (GA), or Dynamic Programming(DP).In presence of uncertainty the planner aims at findingrobust and flexible plans to reducethe risk of considerablelosses. Several measures of risk are discussed. It is shownthat measuring risk by regret may lead to risky solutions,therefore an alternative measure - Expected Maximum Value - issuggested. The general future model, called fuzzy-probabilistictree of futures, integrates all classes of uncertain parameters(probabilistic, fuzzy and truly uncertain).The suggested network planning software incorporates threeefficient applications of GA. The first algorithm searchessimultaneously for the whole set of Pareto optimal solutions.The hybrid GA/DP approach benefits from the global optimizationproperties of GA and local search by DP resulting in originalalgorithm with improved convergence properties. Finally, theStochastic GA can cope with noisy objective functions.Finally, two real distribution network planning projectsdealing with primary distribution network in the large city andsecondary network in the rural area are studied.
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| 3. |
- Steen, David, 1983, et al.
(författare)
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Scheduling Charging of Electric Vehicles for Optimal Distribution Systems Planning and Operation
- 2011
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Ingår i: CIRED 21st International Conference on Electricity Distribution, Frankfurt, 6-9 June 2011.
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Konferensbidrag (refereegranskat)abstract
- In the not so distant future, it is expected a large-scaleintegration of fleets of plug-in electric vehicles (PEVs) inthe transport sector. Such large number of PEVs willincrease the demand of electrical energy and as aconsequence the losses in the electric distribution gridwill increase. Equally there might be a need to reinforcethe grid to be able to adequately supply the increasedload. This paper presents a model to schedule thecharging of PEVs while minimizing the grid losses. Themodel can also determine the maximum number ofvehicles that can be handled by the grid without any needfor reinforcement. The result shows that the losses can bereduced with up to 6% as compared to those of theuncontrolled charging and the number of vehicle that canbe handled by the grid increases substantially.
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