| 1. |
- Kehoe, Laura, et al.
(författare)
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Make EU trade with Brazil sustainable
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Babu, Sajeesh, 1987-, et al.
(författare)
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Analyses of Smart Grid Technologies and Solutions from a System Perspective
- 2015
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Ingår i: Smart Grid Technologies - Asia (ISGT ASIA), 2015 IEEE Innovative. - : IEEE conference proceedings. - 9781509012374 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- This paper consolidates the data, analysis andobservations from a case study conducted in cooperation withthe Smart Grid Gotland project. The analysis identifies howelectrical power consumption interacts with distributedelectricity generation such as wind and solar power andpresents how it correlates to weather data and smart gridsolutions. The analysis model developed based on the Gotlandnetwork is generic and hence can be functional in investigatingother power networks of different size, voltage level andstructures. The key observations from the study of smart gridsolutions such as dynamic load capacity and energy storagesolutions are specified. Based on the project, an overview offuture risks and opportunities of smart grid systems is presented.
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| 3. |
- Babu, Sajeesh, et al.
(författare)
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On the status of reliability studies involving primary and secondary equipment applied to power system
- 2014
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Ingår i: 2014 International Conference on Probabilistic Methods Applied to Power Systems, PMAPS 2014 - Conference Proceedings. - : IEEE. - 9781479935611 ; , s. 6960653-
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Konferensbidrag (refereegranskat)abstract
- Growth in infrastructure and energy utilization consistently put forward the demand for added quality and quantity of electric power. Reliability concerns over power systems are widespread within its different associated divisions like 'primary' power system structure, protection system, control equipment, ICT (Information and Communication Technologies) etc. This paper is a review of the present status of practices regarding reliability analysis in these divisions and works towards collectively assessing some of the studies in the respective areas. The idea of integrating reliability analysis from the above areas is introduced along with pointing out the major challenges associated. A set of tools for operators to make use in these reliability evaluations and modelling are mentioned. The earlier attempts towards combined overall system reliability analysis are discussed and the approach in this regard with the help of 'control functions' is emphasised. The paper includes works dealing with theory, different methodologies and data associated with power system reliability.
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| 4. |
- Brodersson, Anna Lilly, et al.
(författare)
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Towards health assessment : Failure analysis and recommendation of condition monitoring techniques for large disconnector populations
- 2016
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Ingår i: CIRED Workshop -. - Helsinki : Institution of Engineering and Technology. ; , s. 4-
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Konferensbidrag (refereegranskat)abstract
- Condition monitoring of power system equipment is an important part of asset management. Hence, health indices were developed to describe the equipment condition in a linguistic form with the obtained data. The development of health indices requires knowledge about the equipment population under investigation to consider all important factors. Therefore, this paper investigates the failure data of a large disconnector population to identify population characteristics such as failure modes and failure locations. The analysis showed that the functions maneuverability and current carrying are essential to monitor. Moreover, this paper discusses condition monitoring techniques for disconnector and their applicability in large populations. The paper concludes that even without cost intensive investments in condition measurements or higher preventive maintenance costs, a condition evaluation can be performed.
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| 5. |
- Ekstedt, Niklas, et al.
(författare)
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Reliability Data : A Review of Importance, Use, and Availability
- 2014
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Konferensbidrag (refereegranskat)abstract
- For reliability studies of power distribution systems availability and collection of data on reliability is a key aspect. The acquirement of data can be challenging, because it endures effort and experience to know where to obtain accessible types of data. This paper gives the reader a guide to why input data to reliability analyses and asset management are useful, which data that can be obtained, and how to access the different types of data. Also, how to measure data accurately and the quality needed are discussed in the paper.After a general discussion on the benefits of data, we discuss the importance of knowing exactly what the data are measurements of. Furthermore, we argue that data from different contexts, even if seemingly similar, should be used with care. We also state and explain that the amount data restrict the type of analysis that can be conducted. The paper continues with a description of some examples of (to different degrees) open accessible data. Nationally collected reliability data from Swedish utilities, reported to authorities and interest organizations, are described and discussed. We discuss how Swedish weather data, which recently have become free and open, enable more studies on the weather related reliability effects, and some existing test systems are mentioned. A section follows that describes how failure and condition data are typically stored and utilized internally in organizations. Finally, we conclude that the paper is a potential guide and inspiration for anyone planning to conduct a reliability study in the future.
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| 6. |
- Jürgensen, Jan Henning, 1987-, et al.
(författare)
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A Review and Discussion of Failure Rate Heterogeneity in Power System Reliability Assessment
- 2016
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The failure rate is a reliability measure which isused for planning and operation of the power system. Thus far, average or experience based failure rates were applied to power system equipment due to their straightforward implementation. However, this approach limits the accuracy of the gained resultsand neglects the important differentiation between populationand individual failure rates. Hence, this paper discusses and demonstrates the necessity to distinguish between populationand individual failure rates and reviews the existing literature offailure rate estimation within the power system domain. The literature is categorized into statistical data driven approaches and failure rate modelling with focus on different criteria whichcan be used to describe the heterogeneity within populations. The review reveals that the environmental impact was modelled predominantly.
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| 7. |
- Jürgensen, Jan Henning, 1987-, et al.
(författare)
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A Scorecard Approach to Track Reliability Performance of Distribution System Operators
- 2015
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Ingår i: CIRED 2015. - : CIRED - Congrès International des Réseaux Electriques de Distribution.
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Konferensbidrag (refereegranskat)abstract
- Firstly, this paper reviews the current process of reporting reliability data in Sweden. Limitations of reliability indices such as SAIDI and SAIFI are discussed and the need for more reliability measures is stated. The paper suggests the introduction of a reliability performance scorecard to analyse reliability measures in an organized system under different aspects. Furthermore, a set of measurements is provided that can be used to assess a utility’s reliability performance. The use of the scorecard is discussed and its applicability for implementing and tracking regulations. This would result in a better policy-making and a decreased pressure on electric utilities due to a higher understanding of what companies invest to achieve a reliable supply of energy.
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| 8. |
- Jürgensen, Jan Henning, 1987-, et al.
(författare)
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Assessment of Explanatory Variables on the Failure Rate of Circuit Breakers Using the Proportional Hazard Model
- 2018
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Ingår i: 2018 POWER SYSTEMS COMPUTATION CONFERENCE (PSCC). - Dublin, Ireland : IEEE conference proceedings. - 9781910963104
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Konferensbidrag (refereegranskat)abstract
- This paper utilises the proportional hazard model to understand and quantify the impact of explanatory variables on the failure rate of circuit breakers (CB). Particularly, 4496 work orders with 2622 high voltage CBs are investigated with an occurrence of 281 major failures. Different explanatory variables such as CB type, manufacturer, preventive maintenance (PM), and others are gathered to quantify their significance and magnitude of their effect. The results present that PM has a positive impact, the number of operations within the last year a negative impact, and age has a small but negative impact on the failure rate. The CB type is not significant in all analyses which can be explained by examining the PM and age of these CB types. This paper contributes to the understanding of how explantatory variables impact the failure rate which is essential for power system asset management.
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| 9. |
- Jürgensen, Jan Henning, 1987-
(författare)
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Condition-based Failure Rate Modelling for Individual Components in the Power System
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The electrical power grid is one of the most important infrastructures in the modernsociety. It supplies industrial and private customers with electricity and supportsother critical infrastructures such as the water supply. Thus, it is significant that the power grid is a reliable system. However, the power system experiences a hugetransition from classical production methods such as coal and nuclear power plantsto distributed renewable energy forms such as wind energy and photovoltaic. This change to a more distributed system challenges the existing power grid as well as the traditional business models of electric utilities. Thus, cost minimization to increase profitability and improvement of the power grid to increase customer satisfactionare in the focus. One approach to increase the reliability of the grid and decrease maintenance costs is a condition-based maintenance approach which requirescondition monitoring techniques.This thesis introduces into failure rate modelling for individual power system components and develops a method to calculate individual failure rates based onthe average failure rate, failure statistics, and condition monitoring data. This approach includes the analysis of failure statistics to identify failure causes and failure locations which are population characteristics but can be utilized to describe the heterogeneity within the population. Thus, the thesis first introduces into the topic of failure analysis and heterogeneity in populations. Different factors are identified and categorized which describe the condition development of a component overtime. Then, the literature within failure rate estimation is reviewed to present the factors which are used within failure rate modelling and to outline the existingmethods which consider the individual. However, limitations are discussed which emphasize the demand for a new approach. Consequently, this thesis introduce intoa new approach for estimating the failure rate for individual components.
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| 10. |
- Jürgensen, Jan Henning, 1987-, et al.
(författare)
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Estimation of Individual Failure Rates for Power System Components based on Risk Functions
- 2018
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The failure rate is essential in power system reliability assessment and thus far it has been commonly assumed as constant. This is a basic approach that delivers reasonable results. However, this approach neglects the heterogeneity in component populations which has a negative impact on the accuracy of the failure rate. This paper proposes a method based on risk functions, which describes the risk behaviour of condition measurements over time, to compute individual failure rates within populations. The method is applied to a population of 12 power transformers on transmission level. The computed individual failure rates depict the impact of maintenance and that power transformers with long operation times have a higher failure rate. Moreover, the paper presents a procedure based on the proposed approach to forecast failure rates. Finally, the individual failure rates are calculated over a specified prediction horizon and depicted with a 95\% confidence interval.
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