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Design of Electricity Markets for Efficient Balancing of Wind Power Generation
KTH, School of Electrical Engineering (EES), Electric Power Systems.ORCID iD: 0000-0002-2016-1739
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Deploying wind power to a larger extent is one solution to reduce negative environmental impacts of electric power supply. However, various challenges are connected with increasing wind power penetration levels. From the perspective of transmission system operators, this includes balancing of varying as well as - to some extent - uncertain generation levels. From the perspective of power generating companies, changes in the generation mix will affect the market's merit order and, hence, their profits. This thesis focuses on provision and use of flexibility in the Nordic electricity market.

First, this thesis studies wind power variations and accuracy of wind power forecasts in Sweden using statistical methods. Even though today’s wind penetration levels are still low in Sweden, power systems and electricity markets have to cope with these characteristics of variations and forecast errors to a larger extent in future.

Second, it investigates to which extent an increased exchange and use of flexibility that is available in the intraday time-frame could efficiently facilitate system balancing and whether this would also be profitable from the power generating companies' perspective. Here, a simulation model is developed that reflects important aspects of production planning and trading decisions in the intraday time-frame. In a first case study, it is shown that the benefits of internal rescheduling strongly depend on the costs to adjust production plans in the intraday time-frame as compared to real-time. In a second case study, it becomes evident that trading flexibility in the intraday time-frame can reduce the need for system balancing more efficiently than internal rescheduling within each balance responsible party.

Motivated by the positive gains of intraday trading and the challenge of appropriately modelling continuous intraday markets, trading activity and price development on Elbas is investigated. The results provide insights into trading behaviour on a continuous intraday market and show that trading is not always in accordance to the power system's physical situation. To the extent to which better information and adaptations in the market design could improve the market participants' base for trading decisions, policy recommendations and further research questions areas suggested.

Abstract [sv]

Att använda vindkraft i en större utsträckning är en möjlighet att minska elproduktionens negativa miljöpåverkan. Det finns dock också olika utmaningar med stora mängder vindkraft. Från ett systemperspektiv gäller det till exempel att hålla balansen mellan tillförsel och konsumtion av el. Från elproducenternas perspektiv bör vindkraftens påverkan på elmarknaden nämnas eftersom det påverka aktörernas vinster. Avhandlingen titta närmare in i hur man kan få tillgång till mer flexibilitet på produktionssidan.

Avhandlingen består av tre delar. För det första undersöks variationer och prognosfel av vindkraft i Sverige med hjälp av statistiska metoder. Även om andel vindkraft hittills är låg i Sverige, behöver elsystemet och elmarknader i framtiden hantera samma egenskaper av själva variationer och prognosfel som idag men i en större utsträckning.

För det andra undersöks hur den flexibiliteten som finns i tidshorisonten några timmar innan leveranstimmen kan utnyttjas för att integrera vindkraften på ett sätt som är både fördelaktigt från systemets och från aktörernas perspektiv. Undersökningen sker med hjälp av en simuleringsmodell som omfattar viktiga delar i produktionsplanering och intradayhandel. I en fallstudie uppvisas att vinster av intern omplanering är i högsta grad beroende på kostnadsskillnaden mellan omplanering några timmar innan leveranstimmen och anpassning av körscheman under själva leveranstimmen. Resultat av ytterligare en fallstudie uppvisar att det är betydligt billigare och mer effektivt att använda intradayhandel istället för intern omplanering för att utnyttja den befintliga flexibiliteten och för att reducera obalanser som systemoperatörer annars behöver ta hand om under leveranstimmen.

Detta är en anledning till att undersöka handelsmönster på Elbas som är en intradaymarknad med kontinuerlig handel. En annan anledning till den här tredje delen är utmaningarna i att modellera kontinuerlig intradayhandel. Studien beskriver handelsaktiviteten på Elbas och hur priserna utvecklas under handelstiden. Ett resultat är att handeln inte alltid återspeglar den fysiska situationen i elsystemet. I den utsträckningen som ett snabbare informationsflöde och förändringar i marknadsdesignen kunde förbättrar aktörernas underlag för intradayhandel, föreslås förbättringar och öppna forskningsfrågor.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. , viii, 84 p.
Series
TRITA-EE, ISSN 1653-5146 ; 2015:031
Keyword [en]
wind power variations, forecast errors, market design, adjustment markets, trading decisions, continuous intraday trading, variable renewable energy
National Category
Energy Systems
Research subject
Electrical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-171063ISBN: 978-91-7595-652-7 (print)OAI: oai:DiVA.org:kth-171063DiVA: diva2:842154
Public defence
2015-10-09, H1, Teknikringen 33, KTH, Stockholm, 10:15 (English)
Opponent
Supervisors
Projects
Elektra 36141: Korttidsplanering av vatten-värmekraftsystem vid stora mängder vindkraft: System-perspektivet
Note

QC 20150911

Available from: 2015-09-11 Created: 2015-07-14 Last updated: 2015-09-11Bibliographically approved
List of papers
1. Wind Power Forecasting Error Distributions: An International Comparison
Open this publication in new window or tab >>Wind Power Forecasting Error Distributions: An International Comparison
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2012 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Wind power forecasting is essential for greater penetration of wind power into electricity systems. Because no wind forecasting system is perfect, a thorough understanding of the errors that may occur is a critical factor for system operation functions, such as the setting of operating reserve levels. This paper provides an international comparison of the distribution of wind power forecasting errors from operational systems, based on real forecast data. The paper concludes with an assessment of similarities and differences between the errors observed in different locations.

Keyword
wind power forecasting, power system operation, power system reliability, power systems, wind power generation
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-107395 (URN)
Conference
11th Annual International Workshop on Large-Scale Integration of Wind Power into Power Systems as well as on Transmission Networks for Offshore Wind Power Plants Conference
Projects
Elektra 36141: Korttidsplanering av vatten-värmekraftsystem vid stora mängder vindkraft: System-perspektivet
Note

QC 20130116

Available from: 2013-01-16 Created: 2012-12-11 Last updated: 2015-09-11Bibliographically approved
2. Index for wind power variability
Open this publication in new window or tab >>Index for wind power variability
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2014 (English)In: Proceedings of 13th International Workshop on Large-Scale Integration of Wind Power into Power Systems as well as on Transmission Networks for Offshore Wind Power (WIW 2014), 2014Conference paper, Published paper (Refereed)
Abstract [en]

Variability of large scale wind power generation isdependent on several factors: characteristics of installed windpower plants, size of the area where the plants are installed,geographic dispersion within that area and its weatherregime(s). Variability can be described by ramps in powergeneration, i.e. changes from time period to time period. Givenenough data points, it can be described with a probabilitydensity function. This approach focuses on two dimensions ofvariability: duration of the ramp and probability distribution.This paper proposes an index based on these two dimensionsto enable comparisons and characterizations of variabilityunder different conditions. The index is tested with real, largescale wind power generation data from several countries.Considerations while forming an index are discussed, as wellas the main results regarding what the drivers of variabilityexperienced for different data.

Keyword
wind power integration, variations, indices for variability, variable renewable energy sources
National Category
Energy Systems
Research subject
Electrical Engineering; Energy Technology
Identifiers
urn:nbn:se:kth:diva-159449 (URN)978-3-98 13870-9-4 (ISBN)
Conference
13th International Workshop on Large-Scale Integration of Wind Power into Power Systems as well as on Transmission Networks for Offshore Wind Plants, Germany, Berlin, 11/11/14 - 13/11/14
Projects
Elektra 36141: Korttidsplanering av vatten-värmekraftsystem vid stora mängder vindkraft: System-perspektivet
Note

QC 20150409

Available from: 2015-01-30 Created: 2015-01-30 Last updated: 2015-09-11Bibliographically approved
3. Distributed Balancing of Wind Power Forecast Deviations by Intraday Trading and Internal Ex-Ante Self-Balancing - A Modelling Approach
Open this publication in new window or tab >>Distributed Balancing of Wind Power Forecast Deviations by Intraday Trading and Internal Ex-Ante Self-Balancing - A Modelling Approach
2013 (English)In: 2013 24th International Workshop on Database and Expert Systems Applications (DEXA), New York: IEEE , 2013, 176-183 p.Conference paper, Published paper (Refereed)
Abstract [en]

Wind power generation does on the one hand contribute to a less polluting and more sustainable electric power generation mix. On the other hand, its power output is variable and subject to forecast errors. In real-time, deviations from wind power forecast are handled by the system operator. But expected deviations can already me minimised by power generating companies before real-time. Ways to decrease their expected deviations are intraday trading and/or re-scheduling of own power plants. Both can be regarded as forms of self-balancing before the period of delivery (ex-ante), intraday trading as a form of external ex-ante self-balancing and re-scheduling as internal ex-ante self-balancing. Both can decrease the need for real-time balancing by the system operator. As existing intraday markets are often plagued by low liquidity, it is important to model such not-perfectly liquid intraday markets and simulate different trading and scheduling strategies. This paper presents an approach to model the choice between purely internal self-balancing and internal self-balancing combined with intraday trading on a not fully liquid intraday market. Results from the model runs indicate that intraday trading on a not-perfectly liquid market can be beneficial from the producers as well as from the system's perspective. However, it can result in increased costs if the possibilities to trade on the intraday market are very limited. This is important to consider when investigating the question whether it would be beneficial to distribute a larger share of the balancing responsibility among the power generating companies in order to relieve some pressure from the system operator.

Place, publisher, year, edition, pages
New York: IEEE, 2013
Series
Proceedings - International Workshop on Database and Expert Systems Applications, DEXA, ISSN 1529-4188
Keyword
Wind power integration, electricity market, forecast errors, re-scheduling
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-133916 (URN)10.1109/DEXA.2013.47 (DOI)000335791800032 ()2-s2.0-84887932827 (Scopus ID)978-0-7695-5070-1 (ISBN)
Conference
2nd International Workshop on Intelligent Agent Technology, Power Systems and Energy Markets - IATEM '13 within the 24th International Workshop on Database and Expert Systems Applications, DEXA 2013; Prague; Czech Republic; 26 August 2013 through 29 August 2013
Projects
Elektra 36141: Korttidsplanering av vatten-värmekraftsystem vid stora mängder vindkraft: System-perspektivet
Note

QC 20140609

Available from: 2013-11-12 Created: 2013-11-12 Last updated: 2015-09-11Bibliographically approved
4. A Study of Electricity Market Design for Systems with High Wind Power Penetration
Open this publication in new window or tab >>A Study of Electricity Market Design for Systems with High Wind Power Penetration
2011 (English)In: Energy Market (EEM), 2011 8th International Conference on the European, IEEE , 2011, 614-621 p.Conference paper, Published paper (Refereed)
Abstract [en]

This literature review investigates the influence of intermittent wind power on the electricity market pointing out the importance of the market design along with presenting the Nordic, the German and the Spanish electricity wholesale market. Adaptations in the market design could improve the performance of systems with high wind power penetration levels. As a conclusion promising key-issues are listed.

Place, publisher, year, edition, pages
IEEE, 2011
Keyword
Electricity market, wind power, market design
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-46165 (URN)10.1109/EEM.2011.5953084 (DOI)2-s2.0-80052132356 (Scopus ID)978-1-61284-284-4 (ISBN)
Conference
2011 8th International Conference on the European Energy Market (EEM)
Projects
Elektra 36141: Korttidsplanering av vatten-värmekraftsystem vid stora mängder vindkraft: System-perspektivet
Note

© 2011 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20111102

Available from: 2011-11-02 Created: 2011-11-02 Last updated: 2015-09-11Bibliographically approved
5. Approaching wind power forecast deviations with internal ex-ante self-balancing
Open this publication in new window or tab >>Approaching wind power forecast deviations with internal ex-ante self-balancing
2013 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 57, 106-115 p.Article in journal (Refereed) Published
Abstract [en]

Short-term variations in wind power generation make real-time balancing of load and generation a more challenging task for the Transmission System Operator (TSO). One issue of interest that could facilitate the efficient integration of wind power is to shift larger parts of the balancing responsibility from the TSO to the power generating companies. The idea is to reduce the real-time balancing need for the TSO by demanding power generating companies to minimise their expected imbalances. To comply with this, power generating companies can re-schedule their production based on updated production forecasts. As a key of the contribution, this paper analyses internal ex-ante self-balancing, where this re-scheduling is done shortly before the period of delivery and internally within each power generating company. To quantify the value of such a more distributed balancing responsibility, a model has been developed which consists of a sequence of optimisation models. Then, possible trading decisions of power generating companies are evaluated in different situations. This is based on a hydro-thermal generation portfolio within the framework of the Nordic electricity market.

Place, publisher, year, edition, pages
Elsevier, 2013
Keyword
Balancing, Electricity market, Nordic power system, Re-scheduling, Stochastic generation, Wind power integration
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-124351 (URN)10.1016/j.energy.2013.03.033 (DOI)000323355600014 ()2-s2.0-84880702971 (Scopus ID)
Projects
Elektra 36141: Korttidsplanering av vatten-värmekraftsystem vid stora mängder vindkraft: System-perspektivet
Note

QC 20150624

Available from: 2013-06-28 Created: 2013-06-28 Last updated: 2017-08-16Bibliographically approved
6. A description of the operative decision-making process of a power generating company on the Nordic electricity market
Open this publication in new window or tab >>A description of the operative decision-making process of a power generating company on the Nordic electricity market
2014 (English)In: Energy Systems, Springer Verlag, ISSN 1868-3967, E-ISSN 1868-3975, Vol. 5, no 2, 349-369 p.Article in journal (Refereed) Published
Abstract [en]

In a liberalised electricity market, power generating companies face various trading possibilities. In addition, they have to take scheduling decisions. Both kinds of decisions are affected by uncertainties, e.g. power plant outages, uncertain market prices for electricity or imperfect wind power forecasts. This paper presents an overview of the decision-making process of a power generating company on the Nordic electricity market and illustrates how uncertainties affect this process. As a power generating company’s return on investment arises - at least partly - from its trading and scheduling decisions, it is important to optimise those decisions. Therefore, selected optimisation models are listed in a condensed manner. The paper also includes a both detailed and comprehensive description of the market design in the Nordic countries.

Place, publisher, year, edition, pages
Springer, 2014
Keyword
Electricity trading, Power producer, Nordic power system, Decisions under uncertainty, Bidding strategy, Risk management
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-140704 (URN)10.1007/s12667-013-0104-2 (DOI)2-s2.0-84901004341 (Scopus ID)
Projects
Elektra 36141: Korttidsplanering av vatten-värmekraftsystem vid stora mängder vindkraft: System-perspektivet
Note

QC 20140923

Available from: 2014-01-30 Created: 2014-01-30 Last updated: 2017-12-06Bibliographically approved
7. Variability in Large-Scale Wind Power Generation
Open this publication in new window or tab >>Variability in Large-Scale Wind Power Generation
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2016 (English)In: Wind Energy, ISSN 1095-4244, E-ISSN 1099-1824, Vol. 19, no 9, 1649-1665 p.Article in journal (Refereed) Published
Abstract [en]

The article demonstrates the characteristics of wind power variability and net load variability in multiple power systems based on real data from multiple years. Demonstrated characteristics include probability distribution for different ramp durations, seasonal and diurnal variability, and low net load events. In some characteristics the power systems are different, but in others they are significantly similar. Somewhat surprisingly there seems to be no straightforward correlation between wind power penetration level and variability. As long as there are several wind power plants with enough geographical spread, most of the smoothing impact is captured. Wind power variability is mainly explained by the extent of geographical spread, but also higher capacity factor causes higher variability. It was also shown how wind power ramps are auto correlated and dependent on the operating output level. In most cases wind power did not have strong diurnal or seasonal variations in the variability. However, there can be exceptions depending on the latitude and on the local characteristics of the wind resource.

Place, publisher, year, edition, pages
John Wiley & Sons, 2016
Keyword
wind power, variability, net load, variable generation, power systems
National Category
Energy Systems
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-171066 (URN)10.1002/we.1942 (DOI)000386148900006 ()2-s2.0-84949844326 (Scopus ID)
Projects
Elektra 36141: Korttidsplanering av vatten-värmekraftsystem vid stora mängder vindkraft: System-perspektivet
Note

QC 170309

Available from: 2015-07-14 Created: 2015-07-14 Last updated: 2017-12-04Bibliographically approved
8. Trading Behaviour on the Continuous Intraday Market Elbas
Open this publication in new window or tab >>Trading Behaviour on the Continuous Intraday Market Elbas
2016 (English)In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 88, 544-557 p.Article in journal (Refereed) Published
Abstract [en]

Intraday markets for electricity allow for trading of energy until shortly before the period of delivery. This offers market participants a possibility to reduce their expected imbalances and to offer own unused flexibility. Because this form of distributed balancing before the period of delivery can be profitable for market participants and beneficial for system operations, intraday trading is expected to gain more importance in future, especially with increasing shares of variable renewable energy sources in the generation mix.

So far, intraday markets are still a research field with many open questions. This paper contributes by a first analysis of intraday trades on Elbas, one of the European intraday markets. The analysis gives a detailed picture on trading activity and price development and is intended to improve understanding of continuous intraday trading.

Findings include that trading activity differs significantly between price zones, that most trades occur in the last hours before gate closure and that market participants have to handle substantial price variations during the trading period. The paper also investigates the imbalance settlement rules in the Nordic countries and studies which effects one- and two-price imbalance settlement systems have on the market participants' profitability of intraday trading.

Place, publisher, year, edition, pages
Elsevier, 2016
Keyword
intraday adjustment market, distributed balancing, bidding strategies, integration of renewable energy sources, market design
National Category
Energy Systems
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-171065 (URN)10.1016/j.enpol.2015.10.045 (DOI)000366766700052 ()2-s2.0-84949647103 (Scopus ID)
Projects
Elektra 36141: Korttidsplanering av vatten-värmekraftsystem vid stora mängder vindkraft: System-perspektivet
Note

QC 2016-01-12. QC 20160121

Available from: 2015-07-14 Created: 2015-07-14 Last updated: 2017-12-04Bibliographically approved

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Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
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