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- Gertmar, Lars, et al.
(author)
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Wind energy powers-that-be successor generation in globalization
- 2007
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In: IEEE Transactions on Energy Conversion. - 0885-8969. ; 22:1, s. 13-28
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Journal article (peer-reviewed)abstract
- After a historic introduction, today's wind power technology is reviewed on a systems level, with some details, and with some brave suggestions for wind technology 2030 when power electronics (PE) will be some 2000 GW. Eternal themes like "electricity storage" are avoided. Aspects of drive-trains in towers and collection grids in parks are concisely described in the paper's core, including: 1) a power circuit scheme eliminating mechanical stress in geared drive-trains at grid faults and low-voltage ride-through (LVRT); 2) a brushless drive-train with partly rated PE; 3) a clarification of transients in cable collection grids including causes, prevention, and mitigation; and 4) details of interactions between PE and cables at faults. IEEE members are challenged to meet emerging demands, and to host future renewable energy (RE) conversion with education, standards, R&D, and wind system coordination, defined well above automation.
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| 3. |
- Besnard, Francois, 1983-
(author)
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On Optimal Maintenance Management for Wind Power Systems
- 2009
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Licentiate thesis (other academic/artistic)abstract
- Sound maintenance strategies and planning are of crucial importance for wind power systems, and especially for offshore locations. In the last decades, an increased awareness of the impact of human living on the environment has emerged in the world. The importance of developing renewable energy is today highly recognized and energy policies have been adopted towards this development. Wind energy has been the strongest growing renewable source of energy this last decade. Wind power is now developing offshore where sites are available and benefits from strong and steady wind. However, the initial investments are larger than onshore, and operation and maintenance costs may be substantially higher due to transportation costs for maintenance and accessibility constrained by the weather. Operational costs can be significantly reduced by optimizing decisions for maintenance strategies and maintenance planning. This is especially important for offshore wind power systems to reduce the high economic risks related to the uncertainties on the accessibility and reliability of wind turbines. This thesis proposes decision models for cost efficient maintenance planning and maintenance strategies for wind power systems. One model is proposed on the maintenance planning of service maintenance activities. Two models investigate the benefits of condition based maintenance strategies for the drive train and for the blades of wind turbines, respectively. Moreover, a model is proposed to optimize the inspection interval for the blade. Maintenance strategies for small components are also presented with simple models for component redundancy and age replacement. The models are tested in case studies and sensitivity analyses are performed for parameters of interests. The results show that maintenance costs can be significantly reduced through optimizing the maintenance strategies and the maintenance planning.
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| 4. |
- Bojrup, Martin, et al.
(author)
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Multiple Rotating Integrator Controller for Active Filters
- 1999
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In: EPE 99 Conference Proceedings.
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Conference paper (peer-reviewed)abstract
- Abstract in UndeterminedA controller scheme based on multiple rotating integrators (MRI) for an active filter is presented, analysed and evaluated. The inherent performance of integrators in the synchronous reference dq-frame for reduction of steady state errors are used in multiple rotating reference frames in order to compensate harmonics to obtain a steady state error equal to zero. Both measurements and simulations clearly verify the advantageous performance in comparison to presently used active filters. Particularly in experimental verification, the MRI controller structure outperforms the alternative methods due to its low sensitivity to parameter variation and non linear properties of the system. This is particularly important since the superiority of the MRI structure is not fully revealed only by simulation. It is shown that the MRI structure do suppress harmonics to the measurement noise level.
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| 8. |
- Gertmar, Lars, et al.
(author)
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Are DC Currents in an AC Power Distribution the Root Cause for some Abnormalities in AU?
- 2012
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In: 2012 IEEE International Symposium on Electromagnetic Compatibility (EMC). - 2158-110X. - 9781467320610 ; , s. 754-759
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Conference paper (peer-reviewed)abstract
- Abnormalities within a limited number of small and medium enterprises (SMEs) in Australia are reported. A set of interrelated industrial issues are brought out in order to advance the state of knowledge and avoid similar abnormalities / irregularities and to bring back some ideas for the mitigations. Impacts on new automated systems and on industrial as well as safety standards are expected in the long run.
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| 10. |
- Gertmar, Lars, et al.
(author)
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On DC injection to AC grids from distributed generation
- 2005
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In: 2005 IEEE 11th European Conference on Power Electronics and Applications. - 9075815093
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Conference paper (peer-reviewed)abstract
- Distributed generation, DG, introduces multi-generator grids and new modes of operation. DG will likely introduce power electronic, PE, converters on a large scale at the low- and medium-voltage levels. DC injection into the AC grid is a threat from grid-connected PE converters that are badly structured. Low DC currents in AC current are difficult to measure at those low levels decided in IEEE™ 1547 and discussed in other international working groups. Transformers and PE can be co-designed to eliminate DC injection. Modern adjustable-speed drives, ASDs, especially, those with active rectifiers, form a basis to discuss and solve issues of DC injection to AC grids from DG also named distributed energy resources, DER or even DR. DC components from power electronics, embedded in solar power, wind power, energy storage, smart houses, smart-office buildings, own generators, etc. give rise to grid-aspects like AC components give frequencies around the fundamental one. FMEA, failure mode and effects analysis, is judged to be a tool for further synthesis
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