| 1. |
- Bertling, Lina, et al.
(författare)
-
RADPOW development and documentation
- 2008
-
Rapport (populärvet., debatt m.m.)abstract
- This report summarizes the status of the computer program RADPOW. RADPOW is a program for Reliability Assessment of electrical Distribution POWer systems. It was developed at KTH School of Electrical Engineering, within the research program EKC and the research project on reliability of new electrical distribution systems. Further on, RADPOW has been used and further developed within the RCAM research group at KTH School of Electrical Engineering. This status report contains a brief description of the RADPOW_2006 version, the Loadflow module from the RADPOW_1999_PH version and a description of the work done in the resulting RADPOW_2007 version. This version now includes a tested load flow module and the ability to calculate the latest component importance indices developed within the RCAM research group. The source code for the program has also been restructured and commented in a more detailed level than before.
|
|
| 2. |
- Hilber, Patrik, et al.
(författare)
-
Potentiell användning av standardkostnader i regleringen av elnätsföretagens löpande påverkbara kostnader
- 2010
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Potentiell användning av standardkostnader i regleringen av elnätsföretagens löpande påverkbara kostnader har utretts på uppdrag av Energimarknadsinspektionen (EI). Specifikt om mått baserade på Ekm kan användas i regleringen och hur dessa mått bör korrigeras. Ekm (Ekvivalent ledningslängd) är en standardkostnadsmodell där olika entiteter (t.ex. mängd av en komponentkategori) av elnät tilldelas en kvot för årlig drift- och underhållskostnad i förhållande till 1 km 0,4 kV luftledning. Projektets huvudslutsats är att existerande Ekm, tillhandahållna av Svensk Energi, inte kan användas utan rigorösa kontroller och omfattande utveckling, vilket entydigt styrks av utförda analyser. Emellertid finns det en potential att använda Ekm-liknande mått i kommande reglering. Vid ett eventuellt införande rekommenderas följande: Preliminära Ekm-liknande tal implementeras under första tillsynsperiod för en lägre andel av löpande påverkbara kostnader än ursprunglig plan (25%), förslagsvis så att de medel som omfördelas i genomsnitt blir väsentligt lägre än de medel som omfördelas på grund av kvalitetsregleringen. Noggrann utvärdering görs fortlöpande, vars resultat används för revidering av Ekm till nästkommande tillsynsperiod. Detaljerad analys och utveckling av Ekm liknande tal; förslag på handlingsplan tillhandahålls i appendix. Två enkäter har utformats, huvudenkäten har skickats ut till samtliga nätägare i Sverige. Svarsfrekvensen på denna blev 46 % (motsvarande ca 75 % av kundunderlaget). Uppföljande enkät skickades till de som angivit intresse för fördjupat deltagande (12st). Utöver enkäter bygger studien på material från EBR (del av Svensk Energi) och EI samt diskussioner med dessa och nätägare. Trots mängden empiriskt material har inga konkreta förslag på Ekm liknande mått kunnat tillhandahållas, dels på grund av stora variationer mellan svar och analyser och dels på grund av låg svarsfrekvens i enkäten för de delar som avser konkreta kostnader. I vissa fall ger enkätsvaren och analyserna indikationer på storleksordning för Ekm tal och hur dessa bör justeras. Ytterligare en osäkerhetsfaktor är huruvida nuvarande indelning är lämplig, dvs. om fler eller färre objektiva förutsättningar, t.ex. terräng, bör tas i beaktning. Detta är kopplat till den viktiga frågan om att kunna göra en analys av utfallet av ett införande, innan implementering (hur kommer intäkterna omfördelas). Detta har ej kunnat göras då företagen ännu ej rapporterat in sina nät-tillgångar. Studiens viktigaste resultat: Möjliggörande för samtliga parter att bidra med synpunkter innan eventuell skarp implementering. Inventering nuvarande förutsättningar avseende Ekm. Indikation på hur vissa mått bör modifieras. Metoder för utvärdering och bestämmande av nya mått. Ökad medvetenhet och kunskap hos myndighet och nätföretag. Handlingsplan för fortsatt arbete.
|
|
| 3. |
- Hilber, Patrik, et al.
(författare)
-
Risk analysis for power systems : overview and potential benefits
- 2010
-
Konferensbidrag (refereegranskat)abstract
- This paper provides a mapping and sample of recently developed risk assessment techniques that are available for the distribution system operator. Three estimates on the value of more detailed risk analysis are desccribed. I.e. component reliability importance indices can be used to divversify the maintenance efforts, gaining better expected system performance at no cost. Furthermore, components that are assumed to be relatively harmless (based on average values) are identified as critical for longer interruptions. Finally it is shown that losses in a transformer are critical in the decision on transformer lifetime.
|
|
| 4. |
- Setréus, Johan, 1980-, et al.
(författare)
-
Maintenance and Investment Optimization in Distribution Systems
- 2007
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report desccribes a method of minimizing the reliability indices SAIDI or SAIFI for a distribution system given a limited budget and a number of possible maintenance and investment alternatives. The opposite problem, minimizing the total cost with an appropriate level of reliability, has also been modeled. The method is general and can include both investments such as a replacement of overhead line to cable or a redundant line. The result from the method is the investment alternatives that is optimal to perform at the moment. The method is desccribed in the report with the help of a test system with a number of investment alternatives and constraints. The optimization model for the test system is implemented in the computer software AMPL and evaluated with the Cplex solver. The results from the model are reasonable. In order to evaluate how stable the solution is, a sensitivity analysis has also been performed. In the closure of the report a discussion of future work and development of the method is suggested.
|
|
| 5. |
- Setreus, Johan, 1980-, et al.
(författare)
-
RACalc : a Power Distribution Reliability Tool
- 2010
-
Ingår i: 2010 IEEE 11th International Conference on Probabilistic Methods Applied to Power Systems (PMAPS). - : IEEE. ; , s. 154-159
-
Konferensbidrag (refereegranskat)abstract
- One major objective of maintenance management activities in electrical distribution systems is to find the right level of investments. Within an MSc thesis project at KTH, the probabilistic reliability software RACalc has been developed to support the decision making in the distribution system maintenance planning and risk analysis. This paper desccribes the algorithms in RACalc and shows on present status on RADPOW, an additional reliability tool developed within the research group. Calculations with RACalc is in this paper exemplified with a case study on an existing Swedish distribution system, were the program is used to determine the components’ importance to the system reliability indices. The result show that if the failure rate can be decreased by 10% on the 21% most important components, the overall system reliability improvement is more than 7%.
|
|
| 6. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
Model of Capacity Demand under uncertain Weather
- 2010
-
Ingår i: Proceedings IEEE International Conference on Probabilistic Methods Applied to Power Systems (PMAPS). - : IEEE. - 9781424457236 ; , s. 314-318
-
Konferensbidrag (refereegranskat)abstract
- Load forecasting is important in the operation of power systems. The characteristics of the electrical energy consumption are analyzed and its variation as an effect of several weather parameters is studied. Based on historical weather and consumption data received from a distribution system operator (DSO), numerical models of load forecasting are suggested according to electrical power consumption and on daily peak power respectively. Two linear regression models are presented: simple linear regression (SLR) with one input variable (temperature) and multiple linear regressions (MLR) with several input variables. The models are validated with historical data from other years. For daily peak power demand a MLR model has the lowest error, but for prediction of energy demand a SLR model is more accurate.
|
|
| 7. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
The potential of Using EQUIVALENT COMPARISON STANDARDS to judge EFFECTIBLE COSTS in Electrical Distribution tariff regulation
- 2011
-
Ingår i: CIRED2011, Frankfurt 6-9 June 2011, Paper 0646. - : CIRED. ; , s. 1-4
-
Konferensbidrag (refereegranskat)abstract
- Sweden will implement a new tariff regulation from 2012. This paper presents results from a project initiated by the Swedish regulator, performed by the RCAM (Reliability Centered Asset Management) research group aimed to review the potential of using equivalent comparison standards to judge effectible costs. The study includes interviews and surveys distributed to every Swedish distribution system operator (DSO). However, no sharp proposal on units appropriate to use in the first regulatory period (2012-2015) could be provided, due to e.g. large variations in response from the DSOs. The study provides several results such as enabling for all parties to contribute their views before implementation; indication of how current units should be modified; increased knowledge for involved parties and an action plan for future work. The regulator’s initial idea was to apply this kind of model to 25 % of the effectible cost part during the first regulatory period, but based on this study the regulator changed this plan.
|
|
| 8. |
- Babu, Sajeesh, 1987-, et al.
(författare)
-
Analyses of Smart Grid Technologies and Solutions from a System Perspective
- 2015
-
Ingår i: Smart Grid Technologies - Asia (ISGT ASIA), 2015 IEEE Innovative. - : IEEE conference proceedings. - 9781509012374 ; , s. 1-5
-
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.
|
|
| 9. |
- Bergerland, Sune, et al.
(författare)
-
Summary of the Swedish tariff regulation and impact of changes on investment strategies
- 2015
-
Konferensbidrag (refereegranskat)abstract
- This paper evaluates how upcoming changes in the Swedish tariff regulation could affect distribution system operators (DSOs), with focus on reinvestment planning. This is done by general analyses as well as by authentic calculation examples of a real power distribution system. The paper describes the Swedish tariff regulation with expected changes, provides a summary of changes in Swedish laws and regulation affecting DSOs between 1996 and 2016, describes how a DSO at local distribution level conduct their reinvestments, illustrates economic calculation examples and finally presents analyses and conclude the results. Analysis results presented show that the outcome from the regulation is sensitive towards relatively small changes in WACC and age structure. The tariff cap allowed will however be significantly reduced for all tested scenarios. A reinvestment rate of in average~10 % regarding meters and IT and ~2.5 % regarding all other categories could be a rough guideline to meet the new incentives, but that could differ depending on the actual age structure of the DSO.
|
|
| 10. |
- Bertling, Lina, et al.
(författare)
-
Evaluation of the Customer Value of Component Redundancy in Electrical Distribution Systems
- 2005
-
Ingår i: Power Tech, 2005 IEEE Russia. - : IEEE. - 9785932080344 ; , s. 1-8
-
Konferensbidrag (refereegranskat)abstract
- A new regulatory model for the Swedish electrical distribution system operators has been proposed, and is now being implemented. The model is referred to as the Network Performance Assessment Model (NPAM). The NPAM is based on fictive reference networks. These emanate from a radial network that is reinforced with redundant components if it increases the customer value more than required investment cost for higher system reliability. The NPAM involves a paradigm shift for the Swedish DSO from a system based on compensation for costs to one based on performance. Evidently, it is of great importance to both the regulator and the different DSOs to evaluate how well the NPAM calculates the performance i.e. the customer values. The aim for this paper is to take a first step in this process; by putting light on how these redundant reference networks are created and used for the NPAM. In order to do this a comparative study has been made for a small test system where two different approaches are used for identifying the resulting redundant reference network for a system. The NPAM approach uses a Monte Carlo simulation technique, and the comparative approach uses an analytical based reliability assessment tool RADPOW, developed at KTH.
|
|
| 11. |
- Bertling, Lina, et al.
(författare)
-
Excercises on reliability assessment of electric power systems
- 2007
-
Annan publikation (populärvet., debatt m.m.)abstract
- This compendium is collection of exercises for the course on reliability assessment of electric power systems. The course has been developed within the RCAM group at KTH School of Electrical Engineering. The first version of the compendium was prepared in 2005, with examples made by master theses students Carl Johan Wallnerström and Otto Wilhelmsson, in co-operation with Lina Bertling. This updated version has been translated to English by Ph.D. student Andrea Lang.
|
|
| 12. |
|
|
| 13. |
- Ekstedt, Niklas, et al.
(författare)
-
Reliability Data : A Review of Importance, Use, and Availability
- 2014
-
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.
|
|
| 14. |
- Hilber, Patrik, et al.
(författare)
-
Benefits of Reliability Centred Asset Management
- 2013
-
Ingår i: 22nd International Conference and Exhibition on Electricity Distribution (CIRED 2013). - : Institution of Engineering and Technology. - 9781849197328 ; , s. 0668-
-
Konferensbidrag (refereegranskat)abstract
- This paper provides an overview of risk and reliability assessment techniques, some which are available for distribution system operators, and others that are in the process of development. The main contribution of this paper is showing the possibilities and benefits of detailed risk and reliability analysis. Six samples of findings from research developed over the last decade within the RCAM group (Reliability Centred Asset Management) at the Royal Institute of Technology, Stockholm Sweden, are presented. The research is directly associated with risk and asset management applied to power systems. The first three examples are within developed research, followed by three areas where great potential is seen: 1) The value of accurate thermal models of transformers; 2) The impact of tariff regulation on asset management decisions; 3) Detailed interruption studies; 4) Dynamic rating; 5) Combined risk and reliability analysis of primary equipment and control equipment; 6) Systematic diagnostic measures for asset management.
|
|
| 15. |
- Rinnemo, Henrik, et al.
(författare)
-
An example of investment planning of power distribution using quantitative reliability and cost analyses
- 2011
-
Ingår i: 21st International Conference on Electricity Distribution. - : CIRED. ; , s. 1-4
-
Konferensbidrag (refereegranskat)abstract
- From 2012, there will be a new regulation of the electrical power distribution system tariffs in Sweden. Still there are uncertainties regarding the final content, but the basic concept is now settled. Known parts of the new regulation have been used as input to the economic analysis of a potential investment in a Swedish power distribution system owned by Fortum Distribution. The described method could however be applied on any European power distribution system, with adaptation to national laws and regulations. First, a reliability model of the concerned part of the system was created for every potential investment alternative. Quantitative reliability analyses were then performed on these models. Based on calculated reliability indices and assumptions regarding the new regulation, outage costs were calculated. These costs were used as input to life cycle cost (LCC) analyses including more parameters, e.g. maintenance costs. Different investment proposals were evaluated and compared. Sensitivity analyses with respect to increasing outage compensation and WACC (weighted average cost of capital) were made, supporting the same investment. In this case, one investment alternative was clearly pointed out as the best.
|
|
| 16. |
- Stenberg, Sabina, et al.
(författare)
-
The new Swedish Regulation of Power Distribution System Tariffs : A Description and an Initial Evaluation on its Risk and Asset Management Incentives
- 2012
-
Konferensbidrag (refereegranskat)abstract
- From 2012, a new tariff regulation has been introduced in Sweden. A reasonable revenue framework for the distribution system operators (DSOs) is determined before the regulatory period of four years. The aim of this paper is to overall describe the new regulation, especially reliability aspects, including an approach to superficially perform an initial investigation/evaluation on its incentives of risk and asset management. A recently performed M.Sc. thesis by one of the authors shows that the new regulatory method has a great impact on project planning. For example introducing more components is “rewarded”, while demolish old components is “punished”. The DSOs send a proposition to the Energy Markets Inspectorate (EI), who decides whether the suggested frame work is reasonable. The evaluations of the proposed revenue framework is performed by a template method, where EI calculates the reasonable total costs and fair return on capital, with the aim of taking objective prerequisites for the specific DSO into account. After the regulatory period, the DSO’s actual revenue is investigated; if this revenue differs from predetermined levels, the framework will, for the next regulatory period, be reduced or increased.
|
|
| 17. |
- Talpur, Saifal, et al.
(författare)
-
Implementation of Dynamic Line Rating technique in a 130 kV Regional Network
- 2014
-
Ingår i: Multi-Topic Conference (INMIC), 2014 IEEE 17th International. - : IEEE conference proceedings. - 9781479957545 ; , s. 1-6
-
Konferensbidrag (refereegranskat)abstract
- This paper investigates the possibility of using Dynamic Line Rating (DLR) to increase the existing power transmission capacity of overhead lines. The main contribution is to combine theoretical calculations and modeling with real application to conclude benefits of DLR. Both introduction of relevant theory and a case study on a power distribution system in Sweden are included. The concept of DLR implies that the capacity of a component dynamically varies as a function of external parameters, such as weather conditions and loading history. Traditionally, the rating is statically set from simulations of worst-case scenarios. Based on conventional static line rating (SLR) methods, the actual current carrying capability of overhead conductors is underestimated. When an increase in the line current capacity is needed, overhead lines may be rated based on a method that allows system operators to run the lines closer to their actual real-time capacity. Furthermore, the paper addresses the problems of observing safe ground clearance requirements. Knowing the conductor temperature, when it transmits the required electricity is an important factor to be taken into consideration. Therefore, based on real-time ambient conditions with actual line loading and with the help of IEEE-738-2006 standard, the conductor temperature is also calculated in this paper. Finally, an economic analysis is performed to evaluate the financial advantages of applying the dynamic line ratings approach compared to traditional static line ratings technique for a specific overhead conductor (VL3).
|
|
| 18. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
A Pre-Study Towards Investigating the Art of Choosing Right Level of Input Data
- 2012
-
Konferensbidrag (refereegranskat)abstract
- The international tendency towards quality regulation of power distribution tariffs, along with a generally increased pressure of cost efficiency with maintained high reliability, give incentives to introduce more advanced analysis methods within asset management and project planning. This paper proposes a method to compare existing analysis methods with other methods or improvements of current method without perform any sharp changes in the organization. The approach is to compare recently performed risk reducing investments, based on current analysis methods used by the company, and then perform a hypothetical investment planning process based on more comprehensive reliability analysis. This paper presents results from a pre-study of a collaborative project between the industry and the academy to highlight and investigate the art of choosing right detail level of input data used within reliability analysis of power distribution. The aim of the paper is also to: on one hand provide academic reference material from the “reality”, and on the other hand to inspire the industry to review their current analysis methods and if needed, implement improvements.
|
|
| 19. |
|
|
| 20. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
Analys av smartaelnätsteknologier inom kategorin elnätslösningar
- 2014
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna rapport presenterar resultat från en studie där inverkan av så kallade smartaelnätsteknologier/lösningar har analyserats. Utöver egna analysresultat identifieras behov av framtida forskning, detta kompletteras med hänvisningar till fördjupningsmaterial Smartaelnätsteknologier innebär nya möjligheter, men också nya utmaningar och risker. Ett behov av att utveckla nya metoder för tillförlitlighetsberäkningar och riskanalys har identifieras. På grund av bristande erfarenhet gällande många nya tekniker och lösningar av smartaelnätsteknologier är det värdefullt med demonstrationsanläggningar såsom Smart Grid Gotland, varifrån indata har erhållits. Information om Smart Grid Gotland och Gotlands elkraftsystem sammanfattas i rapporten. Gotlands regionnät har även implementerats i datorverktyget NEPLAN. En visuell modell av ett elnät med integrerade smartaelnätsteknologier som kan illustrera möjligheter och utmaningar ur ett systemperspektiv. I rapporten behandlas även frågan om framtida kompetensbehov till följd av smarta elnät ur ett riskperspektiv. En stor mängd timvis väderdata har bearbetats och analyserats tillsammans med timvis data för elkonsumtion och lokal elproduktion. Samband mellan olika parametrar har identifierats, vilka kan vara värdefulla att använda sig av vid utvecklandet av smarta lösningar i elnätet. Resultat från denna initiala analys av indata har använts i genomförda analyser, men kan även vara användbarts referensmaterial i andra studier. Ett analysverktyg har tagits fram för att analysera integrering av elproduktion från både vindkraftturbiner och solkraft, analys av acceptgränser, dynamisk belastningsförmåga och energilager. Hänsyn tas till vädrets påverkan på elproduktions- och elkonsumtionsmönster samt överföringskapacitet. Dynamisk belastningsförmåga innebär att systemets överföringskapacitet varierar dynamiskt med avseende på externa parametrar såsom väder, vilket ökar möjligheten att nyttja ekraftsystem mer effektivt. Analysresultat från flera olika scenarion presenteras i rapporten, vilka visar på olika exempel avseende hur elnätet kan hantera högre maxnivå av elkonsumtion och/eller elproduktion utan fysiska nätförstärkningar. I rapporten presenteras även exempel på hur denna lösning i vissa fall kan öka leveranssäkerhet. Potential av att använda sammanlagring mellan elkonsumtion och lokal elproduktion har analyserats, det vill säga hur dessa tar ut varandra. Även resultat för olika risknivåer med avseende på överlast har analyserats för flera olika scenarier, med och utan dynamisk belastningsförmåga. Om överlast endast medför ökat slitage går det att tänka sig att det kan tillåtas under korta perioder. Energilagring har analyserats ur ett teknikneutralt perspektiv och resultat redovisas som kravlistor. Av elproduktion från vindkraftturbiner respektive solkraft och elkonsumtion kan ett lika stort energilager höja maxeffekten av solkraft mer jämfört med övriga analyserade kategorier. Även energilager i systemdel innehållendes både elkonsumtion och elproduktion, vilken har problem med både import- och exportbegränsningar, har analyserats. Denna kombination balanserar ofta varandra så att överlast undviks; energilagret tar hand om de två ytterligheterna: export- respektive importtoppar. Hur energilager potentiellt kan användas för att höja leveranskvalitet har också analyserats. Energilager som hanterar överföringstoppar behöver endast användas under en liten period av årets timmar och skulle därför kunna användas för flera olika saker såsom att öka leverenssäkerhet. I ett appendix till rapporten görs en ansats till att koppla studiens innehåll till rekommendationer presenterade i Samordningsrådet för smarta elnäts handlingsplan.
|
|
| 21. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
Analysis of the future power systems’s ability to enable sustainable energy-Using the case system of Smart Grid Gotland
- 2018
-
Ingår i: Application of Smart Grid Technologies. - : Elsevier BV. ; , s. 373-393
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The electric power system is being modernized to enable sustainable energy. This chapter presents analyses of different new technologies and solutions for such modernized power systems. Analyses presented include the integration of wind and solar power, electricity consumption, dynamic rating, and energy storage. The main contribution is to considerate effects of weather parameters to find synergies. A national smart grid demonstration project at Gotland island in Sweden has been used as the case study. Results show how the power systems can handle more electricity consumption and generation. The study shows new technology solutions that are beneficial for resource-efficient electricity grids. The case study results show that, most of the time, the energy storage will be unused, but that it can be used to increase the system reliability during that time.
|
|
| 22. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
Asset management framework applied to power distribution for cost-effective resource allocation
- 2014
-
Ingår i: International Transactions on Electrical Energy Systems. - : John Wiley & Sons. - 2050-7038. ; 24:12, s. 1791-1804
-
Tidskriftsartikel (refereegranskat)abstract
- There is an international tendency toward increased demand for both cost-efficiency and high reliability of power distribution systems. To meet these demands, asset management methods, including reliability analyses, have been developed. These reliability analyses often utilize only mean values and hence do not take into consideration the consequences of severe events. This paper proposes a framework for more detailed quantitative risk analysis methods. The aim is to allocate resources more cost-effectively. The suggested framework is exemplified and evaluated by implementing it within the analyses of a real power distribution system. The main concept is to divide comprehensive projects into minor analyses and then in a final step compile the results. The proposed analysis framework can be used independently or combined with earlier proposed vulnerability methods. The latter provides a two-dimensional analysis framework. It is shown that totally different investment alternatives could be preferred depending on whether a traditional analysis method using average values is employed compared with the proposed analysis framework, which also considers severe system states. This demonstrates the risks involved in using average values and the strength of the proposed method. Furthermore, it is shown that already available information can be used for improved asset management decision support. In addition, the performed case study gives combined reliability and weather statistics useful as reference material.
|
|
| 23. |
|
|
| 24. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
Fault Management at a Distribution System Operator
- 2012
-
Konferensbidrag (refereegranskat)abstract
- This paper describes the fault management at a distribution system operator (DSO) including all steps, from detection to restoration. Differences in this work depending on equipment available are compared such as remote versus manual disconnectors. Often, in reliability models of power distribution, a restoration time is assumed; sometimes divided into parts such as an identification time and a repair/switching time. The approach is to describe the actual work by interviewing several people working at a DSO. Furthermore results from a former study at the same DSO are summarized to provide a complete picture of the asset management at a DSO.The aim of this study is to provide a detailed description of actual work to use as reference when developing more comprehensive analysis methods. Another possible usage is to improve current asset management by e.g. identify potential improvements in working methods using existing equipments or to use as input to project planning. These kinds of studies decrease the gap between theoretical models and the reality of workers at DSOs, which probably is the most important contribution of this paper.
|
|
| 25. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
Impact from Dynamic Line Rating on Wind Power Integration
- 2015
-
Ingår i: IEEE Transactions on Smart Grid. - : IEEE Press. - 1949-3053 .- 1949-3061. ; 6:1, s. 343-350
-
Tidskriftsartikel (refereegranskat)abstract
- The concept of dynamic rating (DR) implies that the capacity of a component varies dynamically as a function of external parameters, while the rating traditionally is based on the worst-case. The value of DR thus lies in utilizing existing equipment to a greater extent. By implementing DR and correlating the new ratings with wind power generation, more generation can be implemented. The aim is hence to facilitate connection of renewable electricity production. This paper provides two main contributions: 1) a general dynamic line rating (DLR) calculation model on overhead lines; and 2) an economic optimization simulation model regarding wind power integration comparing DLR with more traditional approaches. These models can both be implemented together, but also separately. The DLR calculation model is easy to use by companies in daily operation where the dynamic line capacity is calculated as a function of static line capacity, wind speed, and ambient temperature. The DLR calculation model is furthermore compared with more comprehensive calculations that validate that the model is accurate enough. This paper also provides an application study where both proposed models are exemplified together and evaluated. Results from this study conclude that it is a significant economic potential of implementing DR within wind power integration.
|
|
| 26. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
Implementation and evaluation of commonly used risk analysis methods applied to a regional power distribution system
- 2013
-
Ingår i: CIRED. - : IEEE. - 9781849197328 ; , s. 0808-
-
Konferensbidrag (refereegranskat)abstract
- This paper describes risk management at the power distribution system of Gotland, the largest island in the Baltic Sea. Concerns regarding that existing risk management not suit all specific conditions initiated this study. The paper shortly describes some existing risk analysis methods that could be relevant to use and summarize and evaluate performed risk analyses. The results indicated two problems with current risk management: one related to analysis methods of regional power lines (70/30 kV) and the other on analysis methods used on substations. Existing methods was hence adjusted and these modified methods where then evaluated with satisfactory results. The aim of the work is to find good risk analysis methods for a specific power system. The project is an university and industry collaboration. By describing a real case and combine industry and academic knowledge, existing methods can be evaluated and, if needed, developed. The results can hopefully be useful, both by companies that will perform risk analysis and by method developers.
|
|
| 27. |
|
|
| 28. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
Laws And Regulations Of Swedish Power Distribution Systems 1996-2012 : learning from novel approaches such as less good experiences
- 2010
-
Konferensbidrag (refereegranskat)abstract
- This paper gives an overview of a turbulent time for the regulator and distribution system operators (DSO) in Sweden since the de-regulation of the electricity market in 1996. A performance based ex-post model was introduced 2003 as a tool to judge distribution system tariffs. This model is since 2009 formally abandoned and a new exante regulation will be introduced in 2012. The aim of this paper is to learn from both unique and novel approaches such as less good experiences. The paper desccribes the history, the current situation and planed future regulations and desccribes additional relevant laws.
|
|
| 29. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
Learning from Experiences of the prior Swedish Electrical Distribution System Regulation : Reference Material when Developing the Future Regulatory Incentives
- 2010
-
Ingår i: Innovative Smart Grid Technologies Conference Europe (ISGT Europe), 2010 IEEE PES. - : IEEE. - 9781424485093 - 9781424485109
-
Konferensbidrag (refereegranskat)abstract
- The electric power system is under an extensive development phase. This change is today normally expressed in the concept of Smart Grid. It captures different developments for a sustainable electric power system, e.g. including large changes at the electrical distribution level with new features for electricity customers. One move in these changes is the larger role of the regulator. In Sweden, a performance based regulatory model was introduced in 2003 as a tool to support in judging if the distribution system operators (DSOs) was charging the customers the right level of tariffs. The model was referred to as the Network Performance Assessment Model (NPAM). The NPAM was an international unique and innovative regulatory tool. The model evaluated tariffs by enter several system data to a computer program which produce a fictive network with the aim of having the same objective conditions as the real system. However, the NPAM was strongly criticized and since 2009 formally abandoned and a new regulation will be introduced 2012. Moreover, the NPAM not support climate incentives such as low losses, which will be a challenge when adopting a smart grid perspective into the regulation of distribution system tariffs in the future. The authors of this paper have followed the development of this model, and have a unique insight in the complexity behind the model. No stringent description of the NPAM is available. This paper aims to fill this gap by providing an overall picture of the NPAM including hitherto unpublished details on underlying theory. This could hopefully inspire and give a reference when developing regulations in different countries in the future by learning from its novelties as well as from its drawbacks.
|
|
| 30. |
- Wallnerström, Carl Johan, 1980-
(författare)
-
On Incentives affecting Risk and Asset Management of Power Distribution
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The introduction of performance based tariff regulations along with higher media and political pressure have increased the need for well-performed risk and asset management applied to electric power distribution systems (DS), which is an infrastructure considered as a natural monopoly. Compared to other technical systems, DS have special characteristics which are important to consider. The Swedish regulation of DS tariffs between 1996 and 2012 is described together with complementary laws such as customer compensation for long outages. The regulator’s rule is to provide incentives for cost efficient operation with acceptable reliability and reasonable tariff levels. Another difficult task for the regulator is to settle the complexity, i.e. the balance between considering many details and the manageability. Two performed studies of the former regulatory model, included in this thesis, were part of the criticism that led to its fall. Furthermore, based on results from a project included here, initiated by the regulator to review a model to judge effectible costs, the regulator changed some initial plans concerning the upcoming regulation. A classification of the risk management divided into separate categories is proposed partly based on a study investigating investment planning and risk management at a distribution system operator (DSO). A vulnerability analysis method using quantitative reliability analyses is introduced aimed to indicate how available resources could be better utilized and to evaluate whether additional security should be deployed for certain forecasted events. To evaluate the method, an application study has been performed based on hourly weather measurements and detailed failure reports over eight years for two DS. Months, weekdays and hours have been compared and the vulnerability of several weather phenomena has been evaluated. Of the weather phenomena studied, heavy snowfall and strong winds significantly affect the reliability, while frost, rain and snow depth have low or no impact. The main conclusion is that there is a need to implement new, more advanced, analysis methods. The thesis also provides a statistical validation method and introduces a new category of reliability indices, RT.
|
|
| 31. |
- Wallnerström, Carl Johan, 1980-
(författare)
-
On Risk Management of Electrical Distribution Systems and the Impact of Regulations
- 2008
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Swedish electricity market was de-regulated in 1996, followed by new laws and a new regulation applied to the natural monopolies of electrical distribution systems (EDS). These circumstances have motivated distribution systems operators (DSOs) to introduce more comprehensive analysis methods. The laws, the regulation and additional incentives have been investigated within this work and results from this study can be valuable when developing risk methods or other quantitative methods applied to EDS. This tendency is not unique for Sweden, the results from a comparative study of customer outage compensation laws between Sweden and UK is for example included. As a part of investigating these incentives, studies of the Swedish regulation of customer network tariffs have been performed which provide valuable learning when developing regulation models in different countries. The Swedish regulatory model, referred to as the Network Performance Assessment Model (NPAM), was created for one of the first de-regulated electricity markets in the world and has a unique and novel approach. For the first time, an overall presentation of the NPAM has been performed including description of the underlying theory as a part of this work. However, the model has been met by difficulties and the future usage of the model is uncertain. Furthermore, the robustness of the NPAM has been evaluated in two studies with the main conclusion that the NPAM is sensitive toward small variations in input data. Results from these studies are explained theoretically investigating algorithms of the NPAM. A pre-study of a project on developing international test systems is presented and this ongoing project aims to be a useful input when developing risk methods. An application study is included with the approach to systematically describe the overall risk management process at a DSO including an evaluation and ideas of future developments. The main objective is to support DSOs in the development of risk management, and to give academic reference material to utilize industry experience. An idea of a risk management classification has been concluded from this application study. The study provides an input to the final objective of a quantitative risk method.
|
|
| 32. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
Potential of dynamic rating in Sweden
- 2014
-
Konferensbidrag (refereegranskat)abstract
- Power system owners are facing major challenges, for example with changed electricity consumption and production patterns; more distributed generation and increased demand of cost efficiency while maintaining high reliability. The concept of dynamic rating can act as a part solution and implies that the capacity of a component is dynamically varying as a function of external parameters such as weather and load history. This hence implies that a component can be better utilized. This can have both direct economic benefits for the utility, but also benefits for the society and the environment by lower tariff levels, faster and cheaper connection of local environmentally friendly electricity production and less climate impact associated with component production and installation. This paper gives a brief introduction to the concept of dynamic rating applied to power systems. Furthermore, results and conclusions from two workshops during 2013 are summarized, where representatives from Vattenfall and Fortum (distribution system operators), ABB (producer and developer that work with dynamic rating solutions), Swedish national grid and several persons from the academia contributed. This was complemented by interviews with the involved companies. The result is a mapping of knowledge, research, development interests, current situation and future visions. All parties show a great interest and see potential, but there are also challenges to be solved.
|
|
| 33. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
Reliability Analysis and Asset Management Applied to Power Distribution
- 2014. - 1
-
Bok (populärvet., debatt m.m.)abstract
- We are becoming more and more dependent on reliable distribution of electricity. The demand for cost efficiency has at the same time increased since new incentives have appeared. This book presents methods for finding a balance between the aims of high reliability and cost effectiveness. A key aspect is to evaluate the impacts of outages and the benefits of risk reducing investments. Put in a wider context, this is asset management, which can be summarized as the art of finding a balance between risk, cost and performance. This book is built on the experience of a wide number of case studies of different reliability projects and is focused on applicable tools for the reader. Basically the book gathers the most important parts of the asset management process into one place.
|
|
| 34. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
Risk and reliability assessment for electrical distribution systems and impacts of regulations with examples from Sweden
- 2010
-
Ingår i: International Journal of Systems Assurance Engineering and Management. - : Springer. - 0975-6809 .- 0976-4348. ; 1:2, s. 87-95
-
Tidskriftsartikel (refereegranskat)abstract
- The introduction of performance based tariff regulations, and higher media and political pressure have increased the need for well-performed asset management in the operation and planning of electrical distribution systems. In this paper quantitative reliability assessment methods are proposed as a tool to meet these new incentives. Electrical distribution systems have compared to other technical systems several special characteristics which are important to take into consideration when introducing reliability analysis methods. Moreover, the paper gives a brief discussion on the effects and the importance of customer participation in improving system reliability by providing additional system operating reserve from the market perspective. Finally, the paper discusses the reliability analysis with the reliability test systems, and stresses the usefulness of generally known test systems for such assessments. The ideas of future work on development of these test systems to address the changing power systems are presented.
|
|
| 35. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
Risk Management Applied to Electrical Distribution Systems
- 2009
-
Ingår i: IET Conference Publications: 20th International Conference and Exhibition on Electricity Distribution, CIRED 2009; Prague; Czech Republic; 8 June 2009 through 11 June 2009. - : IET. - 9781849191265
-
Konferensbidrag (refereegranskat)abstract
- This paper summarizes results from a research project investigating risk management applied to electrical distribution systems (EDS) in Sweden. New incentives have motivated the distribution system operators (DSOs) to consider more comprehensive analysis methods. The project focuses on investigating long term consequences of different project- and maintenance plans. This paper shortly desccribes related research, incentives, results from an application study and future work. The main conclusion is that there is a trend that DSOs use more complex risk management approaches as a result of new incentives.
|
|
| 36. |
- Wallnerström, Carl Johan, 1980-
(författare)
-
Riskanalysbaserat ramverk för projektplanering och underhållsoptimering
- 2013
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Ett kortare (motsvarande 4 månader) postdoktoralt projekt inom ramen för Elforsk riskanalysprogram har utförts av forskargruppen RCAM vid Kungliga Tekniska högskolan. Huvudmålet är att vidareutveckla och dra nytta av resultat från avslutat doktorsprojekt för att ge kontinuitet inom forskningsområdet. Denna rapport inkluderar en introduktion till ämnet, en svensk översättning av riskanalysbeserat ramverk för projektplanering och underhållsoptimering med tillhörande exempel (vilket även har publicerats som två engelska vetenskapliga artiklar), en kort sammanfattning av några övriga artiklar skrivna helt eller delvis under projekttiden samt en avslutande del som inkluderar förslag på framtida forskning inom riskanalys.I många länder, däribland Sverige, har kravet på att hitta en god balans mellan å ena sidan kostnadseffektivitet, å andra sidan god tillförlitlighet i eldistributionssystem ökat som en följd av kvalitetsregleringar, skärpta lagar samt politiskt och medialt tryck. För att möta dessa krav finns det ett behov av att utveckla och implementera mer avancerade analysmetoder. En svår utmaning är att utforma dessa så att de både ger tillfredställande resultat och samtidigt att de inte är för avancerade att implementera i verksamheten hos ett elnätsbolag. En vanlig ansatts för att analysera kundavbrottsrisker i eldistributionsnät är tillförlitlighetsanalys. Traditionellt använder sådana analyser medelvärden och tar därmed inte hänsyn till hela spannet av konsekvenser (exempelvis kostnad för långa avbrott >12 timmar). I detta dokument föreslås ett analysramverk som kan inkludera fler konsekvenser och där komplexitetsnivå lätt kan anpassas till vad som är mest lämplig i varje specifikt fall. Två huvudmål är att beakta fler risker och att fördela resurser mer kostnadseffektivt.Grundidén är att dela upp omfattande analyser i flera mindre delanalyser och sedan i ett sista steg sammanställa resultat. Föreslagna metoder kan användas fristående eller kombineras med tidigare föreslagen sårbarhetsmetod. Uppdelningen i mindre analyser kan illustreras som en matris med olika systemtillstånd på ena axeln och olika resursallokeringsförslag på den andra. Föreslaget analysramverk exemplifieras i rapporten genom att det har implementerats på ett verkligt eldistributionssystem. Det visar sig att resursallokeringssalternativ (t.ex. investeringsförslag) som framstår som mest attraktiva om analys baseras på traditionella metoder, i själva verket har för hög risk när fler aspekter tas i beaktning. Det visar på risker med att använda medelvärden och styrkan i föreslagen metod. Dessutom har genomförd fallstudie visat att, redan för elnätsföretagen tillgänglig information, kan användas även för mer detaljerade analyser än vad som brukar användas idag.
|
|
| 37. |
|
|
| 38. |
- Wallnerström, Carl Johan, 1980-
(författare)
-
Sveriges elektrifiering : grunden för vårt moderna samhälle
- 1999
-
Rapport (populärvet., debatt m.m.)abstract
- I Sverige är 1800-talet industrialiseringens tid. Många nya saker förändrar samhället, men inget så mycket som elektriciteten. På 1900-talet når elektriciteten in i hemmen. Man skaffar sig elektriska apparater vilka banar vägen för vår tids informations samhälle.
|
|
| 39. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
Using power system temperature sensors for moreuses than originally intended : Exemplified by investigating dynamic rating possibilities
- 2014
-
Ingår i: NORDAC 2014 (Eleventh Nordic Conference on Electricity Distribution System Management and Development, Stockholm, 8 - 9 September 2014). - : Elforsk.
-
Konferensbidrag (refereegranskat)abstract
- Power system owners are facing major challenges with changed electricity consumption and production patterns; more distributed generation and increased demand of cost efficiency while maintaining high reliability. Today, the capacity of power components often is set with static limits based on simulations of worst case scenarios. This leads to a discrepancy between the actually-available capacity and the rating itself which unfortunately is left unused. The approach of dynamic rating implies that the capacity of a component is dynamically varying as a function of external parameters such as weather, load history and diagnostic indicators. Svenska kraftnät (Swedish national grid) has installed temperature sensors with the purpose of developing condition monitoring methods in another research project. Within this project, the same infrastructure can perhaps be used to also evaluate dynamic rating algorithms of power lines or to develop new algorithms regarding e.g. disconnectors. Also the thermal modelling in that project can be reused. This paper hence exemplifies the possibility to get more applications without additional costly and complicated investments. The aim of the paper is hence to show on future research possibilities and bring ideas to discussion.
|
|
| 40. |
- Wallnerström, Carl Johan, 1980-, et al.
(författare)
-
Vulnerability Analysis of Power Distribution Systems for Cost-effective Resource Allocation
- 2012
-
Ingår i: IEEE Transactions on Power Systems. - : IEEE Press. - 0885-8950 .- 1558-0679. ; 27:1, s. 224-232
-
Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a method to allocate resources in power distribution planning and also introduces a new reliability index category, RT, flexibility to adjust to different laws or DSO policies of long outages. Possible legal consequences for distribution system operators are first identified and studied. A vulnerability-analysis method is introduced, including a statistical validation. The overall idea is to identify and evaluate possible states of power distribution systems using quantitative reliability analyses. Results should thus indicate how available resources (both human recourses and equipment) could be better utilized, e.g. in maintenance and holiday scheduling and in evaluating whether additional security should be deployed for certain forecasted weather conditions.To evaluate the method, an application study has been performed based on hourly weather measurements and about 65 000 detailed failure reports over eight years for two distribution systems in Sweden. Months, weekdays and hours have been compared and the vulnerability of several weather phenomena in these areas has been evaluated. Of the weather phenomena studied, only heavy snowfall and strong winds, especially in combination, significantly affect the reliability. Temperature (frost), rain and snow depth have a relatively low or no impact.
|
|
