Change search
Link to record
Permanent link

Direct link
BETA
Tomasson, Egill
Publications (10 of 10) Show all publications
Tomasson, E. (2020). Impact of High Levels of Variable Renewable Energy on Power System Generation Adequacy: Methods for analyzing and ensuring the generation adequacy of modern, multi-area power systems. (Doctoral dissertation). Stockholm, Sweden: KTH Royal Institute of Technology
Open this publication in new window or tab >>Impact of High Levels of Variable Renewable Energy on Power System Generation Adequacy: Methods for analyzing and ensuring the generation adequacy of modern, multi-area power systems
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The generation adequacy of electricity supply has been an ongoing concern since the restructuring of the industry. Ensuring generation adequacy was a rather straightforward task in the era of natural monopolies. Whose responsibility was it to ensure generation adequacy as the industry became deregulated and more fragmented? Who is willing to finance rarely used generating units? After decades of experience with the competitive electricity market, the question of whether market forces alone are sufficient to ensure generation adequacy still remains.

Recent energy policies have moreover set a goal of a high share of renewable energy in electricity markets. The presence of high levels of renewable generation makes the supply side of the market more uncertain. This volatility in energy production induces volatility in energy prices which means that the revenue stream of conventional generating technologies is more uncertain than it has traditionally been. This can even deteriorate the economics of some generators to the point where they exit the electricity market. The installed capacity of dispatchable generation can therefore be reduced.

These developments bring up the question of whether the generation adequacy of modern and future, deregulated and highly variable power systems is ensured. This dissertation focuses on modeling the generation adequacy of modern power systems with a high penetration of variable renewable energy sources. Moreover, the dissertation looks at some solutions with the aim of ensuring the generation adequacy of such systems through various means such as coordinated reserves, energy storage as well as utilizing the flexibility of the demand side of the market.

The models developed in this dissertation are verified using well-known test systems as well as through large-scale analysis of real-world systems. Aside from focusing on the simulation of power systems, the developed models moreover focus on achieving high computational efficiency. This is done through means such as advanced Monte Carlo simulation and optimization methods that apply decomposition to speed up the simulations.

Abstract [sv]

Elförsörjningens leveranssäkerhet har varit en källa till oro alltsedan avregleringen av elmarknaden. Att säkerställa produktionens leveranssäkerhet var en ganska enkel uppgift i de tidigare naturliga monopolen. Vems ansvar var det att säkerställa produktionens leveranssäkerhet när industrin blev avreglerad och mer fragmenterad? Vem är villig att finansiera sällan använda produktionsenheter? Efter decennier av erfarenhet av den konkurrensutsatta elmarknaden kvarstår fortfarande frågan om marknadskrafterna är tillräckliga för att säkerställa produktionens leveranssäkerhet.

Energipolitiken i många länder har dessutom satt upp mål för en hög andel förnybar energi på elmarknaderna. Höga nivåer av förnybar produktion gör marknadens utbudssida mer osäker. Denna volatilitet i produktionen inducerar volatilitet i elpriser, vilket innebär att inkomsterna för konventionella produktionstekniker blir mer osäkra än tidigare. Detta kan försämra ekonomin hos vissa generatorer till den grad att de lämnar elmarknaden. Därför kan den installerade kapaciteten för kontrollerbar produktion reduceras.

Denna utveckling väcker frågan om i vilken utsträckning produktionens leveranssäkerhet kan säkerställas i framtida, avreglerade elkraftsystem med hög andel variabel elproduktion. Denna avhandling fokuserar på att modellera produktionens leveranssäkerhet för moderna kraftsystem med en hög andel variabla förnybara energikällor. Avhandlingen tittar dessutom på några lösningar i syfte att säkerställa leveranssäkerheten i sådana system genom olika medel som samordnade reserver, energilagring samt att utnyttja flexibilitet på marknadens efterfrågesida.

Modellerna som utvecklas i denna avhandling verifieras av välkända testsystem samt genom storskalig analys av befintliga kraftsystem. Förutom att fokusera på simulering av kraftsystem fokuserar de utvecklade modellerna dessutom på att uppnå hög beräkningseffektivitet. Detta görs genom medel som avancerad Monte Carlo-simulering och optimeringsmetoder som tillämpar dekomposition för att öka effektiviteten av simuleringarna.

Place, publisher, year, edition, pages
Stockholm, Sweden: KTH Royal Institute of Technology, 2020. p. 171
Series
TRITA-EECS-AVL ; 2020:29
Keywords
Generation adequacy, reliability, renewable energy, Monte Carlo simulation, electricity markets, optimization, mathematical programming
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-273328 (URN)978-91-7873-542-6 (ISBN)
Public defence
2020-06-10, N/A (Via videolink due to Corona virus), 10:00 (English)
Opponent
Supervisors
Note

QC 20200515

Available from: 2020-05-15 Created: 2020-05-13 Last updated: 2020-05-15Bibliographically approved
Tomasson, E., Hesamzadeh, M. R. & Wolak, F. A. (2020). Optimal offer-bid strategy of an energy storage portfolio: A linear quasi-relaxation approach. Applied Energy, 260, Article ID 114251.
Open this publication in new window or tab >>Optimal offer-bid strategy of an energy storage portfolio: A linear quasi-relaxation approach
2020 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 260, article id 114251Article in journal (Refereed) Published
Abstract [en]

This paper proposes a model of the behavior of an expected profit-maximizing merchant storage owner with the ability to exercise unilateral market power. The resulting non-linear bilevel optimization problem is transformed into a single-level stochastic bilinear program using the Karush-Kuhn-Tucker conditions of the lower-level Independent System Operator dispatch problem. By discretizing the offers and bids of the merchant storage owner, the problem is formulated as a stochastic disjunctive program. Using the disjunctive nature of the derived program, a specialized branch-and-bound algorithm that applies a linear quasi-relaxation of the merchant storage problem is proposed. Our solution algorithm is able to solve the problem in an efficient manner; returning the charge and discharge strategies for the merchant storage owner that yield the highest expected profits. Simulations of test systems reveal the various abilities of the merchant storage owner to exercise unilateral market power. Those include demand withholding, generation withholding and under-use which result in an increased congestion in both space and time when compared to the welfare-maximizing use of storage. Factors such as uncertain bids by other players, final state-of-charge requirements and arbitrage by other storage players are investigated. Moreover, numerical results demonstrate the superior computational performance of the proposed solution algorithm when benchmarked against current practices in the literature.

Place, publisher, year, edition, pages
Elsevier Ltd, 2020
Keywords
Bilinear program, Disjunctive program, Linear quasi-relaxation, Merchant storage, Offer-bid strategy, Branch and bound method, Commerce, Electric utilities, Financial markets, Profitability, Stochastic systems, Bid strategies, Bilevel optimization problems, Branch-and-bound algorithms, Independent system operators, Karush Kuhn tucker condition, Quasi-relaxations, Electronic trading, energy efficiency, energy storage, numerical model, optimization
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-267953 (URN)10.1016/j.apenergy.2019.114251 (DOI)000515108700095 ()2-s2.0-85076704156 (Scopus ID)
Note

QC 20200401

Available from: 2020-04-01 Created: 2020-04-01 Last updated: 2020-04-27Bibliographically approved
Söder, L., Tomasson, E., Estanqueiro, A., Flynn, D., Hodge, B.-M., Kiviluoma, J., . . . de Vries, L. (2020). Review of wind generation within adequacy calculations and capacity markets for different power systems. Renewable & sustainable energy reviews, 119, Article ID 109540.
Open this publication in new window or tab >>Review of wind generation within adequacy calculations and capacity markets for different power systems
Show others...
2020 (English)In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 119, article id 109540Article, review/survey (Refereed) Published
Abstract [en]

The integration of renewable energy sources, including wind power, in the adequacy assessment of electricity generation capacity becomes increasingly important as renewable energy generation increases in volume and replaces conventional power plants. The contribution of wind power to cover the electricity demand is less certain than conventional power sources; therefore, the capacity value of wind power is smaller than that of conventional plants. This article presents an overview of the adequacy challenge, how wind power is handled in the regulation of capacity adequacy, and how wind power is treated in a selection of jurisdictions. The jurisdictions included in the overview are Sweden, Great Britain, France, Ireland, United States (PJM and ERCOT), Finland, Portugal, Spain, Norway, Denmark, Belgium, Germany, Italy and the Netherlands.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2020
Keywords
Adequacy, Capacity credit, Capacity markets, Market integration, Power system, Wind power
National Category
Environmental Engineering
Identifiers
urn:nbn:se:kth:diva-269449 (URN)10.1016/j.rser.2019.109540 (DOI)000512406900017 ()2-s2.0-85075946844 (Scopus ID)
Note

QC 20200310

Available from: 2020-03-10 Created: 2020-03-10 Last updated: 2020-03-10Bibliographically approved
Söder, L., Tomasson, E., Estanqueiro, A., Flynn, D., Hodge, B.-M. -., Kiviluoma, J., . . . de Vries, L. (2020). Review of wind generation within adequacy calculations and capacity markets for different power systems. Renewable and Sustainable Energy Reviews, 119, Article ID 109540.
Open this publication in new window or tab >>Review of wind generation within adequacy calculations and capacity markets for different power systems
Show others...
2020 (English)In: Renewable and Sustainable Energy Reviews, Vol. 119, article id 109540Article in journal (Refereed) Published
Abstract [en]

The integration of renewable energy sources, including wind power, in the adequacy assessment of electricity generation capacity becomes increasingly important as renewable energy generation increases in volume and replaces conventional power plants. The contribution of wind power to cover the electricity demand is less certain than conventional power sources; therefore, the capacity value of wind power is smaller than that of conventional plants.

This article presents an overview of the adequacy challenge, how wind power is handled in the regulation of capacity adequacy, and how wind power is treated in a selection of jurisdictions. The jurisdictions included in the overview are Sweden, Great Britain, France, Ireland, United States (PJM and ERCOT), Finland, Portugal, Spain, Norway, Denmark, Belgium, Germany, Italy and the Netherlands.

Keywords
dequacy Capacity credit Capacity markets Market integration Power system Wind power
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-268198 (URN)10.1016/j.rser.2019.109540 (DOI)000512406900017 ()2-s2.0-85075946844 (Scopus ID)
Note

QC 20200406

Available from: 2020-04-06 Created: 2020-04-06 Last updated: 2020-04-06Bibliographically approved
Crosara, A., Tomasson, E. & Söder, L. (2019). Generation Adequacy in the Nordic and Baltic Area: The Potential of Flexible Residential Electric Heating. In: Proceedings of 2019 IEEE PES Innovative Smart Grid Technologies Europe, ISGT-Europe 2019: . Paper presented at 2019 IEEE PES Innovative Smart Grid Technologies Europe, ISGT-Europe 2019; University Politehnica of Bucharest, Bucharest; Romania; 29 September 2019 through 2 October 2019. Institute of Electrical and Electronics Engineers (IEEE), Article ID 8905720.
Open this publication in new window or tab >>Generation Adequacy in the Nordic and Baltic Area: The Potential of Flexible Residential Electric Heating
2019 (English)In: Proceedings of 2019 IEEE PES Innovative Smart Grid Technologies Europe, ISGT-Europe 2019, Institute of Electrical and Electronics Engineers (IEEE), 2019, article id 8905720Conference paper, Published paper (Refereed)
Abstract [en]

Generation adequacy is a concern in today's electricity market where intermittent renewable energy sources are rapidly becoming a greater share of the generation mix. This paper focuses on the North-European power system that is comprised of the system areas of the Nord Pool spot market. Sequential Monte Carlo Simulation is applied to assess the generation adequacy of this multi-area system for several future scenarios defined within the Nordic Flex4RES project. The paper gives insights into the characteristics of these adequacy problems that the system could face in a more sustainable future and quantifies their magnitude. Finally, some solutions based on the demand flexibility of residential electric heating are discussed.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2019
Keywords
EENS, Generation Adequacy, LOLE, Nord Pool, Sequential Monte Carlo Simulation
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-267910 (URN)10.1109/ISGTEurope.2019.8905720 (DOI)2-s2.0-85075900367 (Scopus ID)9781538682180 (ISBN)
Conference
2019 IEEE PES Innovative Smart Grid Technologies Europe, ISGT-Europe 2019; University Politehnica of Bucharest, Bucharest; Romania; 29 September 2019 through 2 October 2019
Note

QC 20200217

Available from: 2020-02-17 Created: 2020-02-17 Last updated: 2020-02-17Bibliographically approved
Crosara, A., Tomasson, E. & Söder, L. (2019). Generation Adequacy in the Nordic and Baltic Region: Case Studies from 2020 to 2050: Flex4RES Project Report. Stockholm: KTH Royal Institute of Technology
Open this publication in new window or tab >>Generation Adequacy in the Nordic and Baltic Region: Case Studies from 2020 to 2050: Flex4RES Project Report
2019 (English)Report (Other academic)
Abstract [en]

Generation adequacy is a concern in today's electricity market where intermittent renewable energy sources are rapidly becoming a greater share of the generation mix. This study focuses on the Nordic and Baltic power system that is comprised of the system areas of the Nord Pool spot market. Sequential Monte Carlo Simulation is applied to assess the generation adequacy of this multi-area system for several future case studies, based on scenarios defined within the Nordic Flex4RES project. The report gives insights into the characteristics of these adequacy problems that the system could face in a more sustainable future, quantifies their magnitude and presents their characteristics. Finally, a solution based on the demand flexibility of residential electric heating is discussed, as a way to counter capacity deficit problems.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019. p. 33
Keywords
Generation Adequacy, Reliability, Electricity Market, Monte Carlo Simulation
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-254940 (URN)
Projects
Flex4RES
Note

QC 20190724

Available from: 2019-07-09 Created: 2019-07-09 Last updated: 2019-07-26Bibliographically approved
Tomasson, E. & Söder, L. (2018). Generation Adequacy Analysis of Multi-Area Power Systems With a High Share of Wind Power. IEEE Transactions on Power Systems, 33(4), 3854-3862
Open this publication in new window or tab >>Generation Adequacy Analysis of Multi-Area Power Systems With a High Share of Wind Power
2018 (English)In: IEEE Transactions on Power Systems, ISSN 0885-8950, E-ISSN 1558-0679, Vol. 33, no 4, p. 3854-3862Article in journal (Refereed) Published
Abstract [en]

There is growing concern regarding generation adequacy within the power system industry. The ever-increasing injection of intermittent renewable resources makes it harder than before to estimate the reliability of modern power systems using traditional approaches. This paper develops a framework for estimating the reliability of modern power systems that have considerable levels of wind power generation. Monte Carlo simulation is applied using a very efficient importance sampling technique based on the cross-entropy method as well as the Copula theory. Tailor-made importance sampling functions for conventional generation, load, and wind power generation drastically reduce the number of samples required to estimate reliability parameters of interest. The methodology enables simulation of multi-area power systems with considerable amount of correlated wind power generation in each of the different areas. Simulation results confirm the efficiency as well as the accuracy of the proposed method and show that it is orders of magnitude faster than crude Monte Carlo simulation.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2018
Keywords
Monte Carlo simulation, cross-entropy (CE) method, power system reliability, Copula theory, wind power, importance sampling, correlation, loss of load probability (LOLP), expected power not served (EPNS)
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-240222 (URN)10.1109/TPWRS.2017.2769840 (DOI)000436009500033 ()2-s2.0-85034237938 (Scopus ID)
Note

QC 20181214

Available from: 2018-12-14 Created: 2018-12-14 Last updated: 2018-12-14Bibliographically approved
Tomasson, E. & Söder, L. (2018). Multi-area generation adequacy and capacity credit in power system analysis. In: 2017 IEEE Innovative Smart Grid Technologies - Asia: Smart Grid for Smart Community, ISGT-Asia 2017. Paper presented at 7th IEEE Innovative Smart Grid Technologies - Asia, ISGT-Asia 2017, 4 December 2017 through 7 December 2017 (pp. 1-6). Institute of Electrical and Electronics Engineers (IEEE)
Open this publication in new window or tab >>Multi-area generation adequacy and capacity credit in power system analysis
2018 (English)In: 2017 IEEE Innovative Smart Grid Technologies - Asia: Smart Grid for Smart Community, ISGT-Asia 2017, Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 1-6Conference paper, Published paper (Refereed)
Abstract [en]

A generator's contribution to the generation adequacy of a power system is more accurately captured by its capacity credit than by its installed capacity. The capacity credit takes into account factors such as forced outages and limited energy supply and the latter is especially important for volatile renewable sources that behave quite differently from dispatchable sources. Their installed capacity gives very limited information about their contribution to the generation system adequacy. Traditional approaches for calculating the capacity credit treat the power system as a single area and calculate an aggregate value for the whole system. In this paper, a multi-area approach is introduced which is able to quantify how the capacity credit is distributed between different power system areas. A combination of an iterative multi-variate Newton approach and a Monte Carlo simulation with an efficient sensitivity analysis allows this to be achieved in a computationally economical way.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2018
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-238206 (URN)10.1109/ISGT-Asia.2017.8378349 (DOI)000435854300036 ()2-s2.0-85049948625 (Scopus ID)9781538649503 (ISBN)
Conference
7th IEEE Innovative Smart Grid Technologies - Asia, ISGT-Asia 2017, 4 December 2017 through 7 December 2017
Note

QC 20181121

Available from: 2018-11-21 Created: 2018-11-21 Last updated: 2018-11-21Bibliographically approved
Tomasson, E. & Söder, L. (2017). Improved Importance Sampling for Reliability Evaluation of Composite Power Systems. IEEE Transactions on Power Systems, 32(3), 2426-2434
Open this publication in new window or tab >>Improved Importance Sampling for Reliability Evaluation of Composite Power Systems
2017 (English)In: IEEE Transactions on Power Systems, ISSN 0885-8950, E-ISSN 1558-0679, Vol. 32, no 3, p. 2426-2434Article in journal (Refereed) Published
Abstract [en]

This paper presents an improved way of applying Monte Carlo simulation using the crossentropy method to calculate the risk of capacity deficit of a composite power system. By applying importance sampling for load states in addition to the generation and transmission states in a systematic manner, the proposed method is many orders of magnitude more efficient than the crude Monte Carlo simulation and considerably more efficient than other crossentropy-based algorithms that apply other ways of estimating the importance sampling distributions. An effective performance metric of system states is applied in order to find optimal importance sampling distributions during presimulation that significantly reduces the required computational effort. Simulations, using well-known IEEE reliability test systems, show that even problems that are nearly intractable using crude Monte Carlo simulation become very manageable using the proposed method.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2017
Keywords
EPNS, importance sampling, LOLP, Monte Carlo simulation, power system reliability, cross-entropy method
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-207660 (URN)10.1109/TPWRS.2016.2614831 (DOI)000399998000072 ()2-s2.0-85018313090 (Scopus ID)
Note

QC 20170602

Available from: 2017-06-02 Created: 2017-06-02 Last updated: 2020-03-27Bibliographically approved
Tomasson, E. & Söder, L. (2016). Multi-area power system reliability evaluation by application of copula theory. In: IEEE Power and Energy Society General Meeting: . Paper presented at 2016 IEEE Power and Energy Society General Meeting, PESGM 2016, 17 July 2016 through 21 July 2016. IEEE
Open this publication in new window or tab >>Multi-area power system reliability evaluation by application of copula theory
2016 (English)In: IEEE Power and Energy Society General Meeting, IEEE, 2016Conference paper, Published paper (Refereed)
Abstract [en]

Evaluating the risk of capacity deficit in large interconnected power systems is an important task in planning studies in order to supply the demand in the system at a certain risk level. It makes it possible to identify in which parts of the system reinforcements are needed in terms of generating capacity and/or interconnections. In modern power systems, with tie lines interconnecting countries and continents as well as an increasing amount of intermittent renewable resources, areas become dependent on each other for generating capacity not only under rare hazardous operating conditions but also in what can be considered as normal operation. This paper presents a novel way of taking inter-area load correlation into account when calculating the risk of capacity deficit by applying Copula sampling. The Monte Carlo simulation method is applied in addition to a Cross-Entropy based importance sampling technique to reduce computation time. The resulting procedure is a computationally effective general method of evaluating the risk of capacity deficit in a large scale multi-area interconnected power system.

Place, publisher, year, edition, pages
IEEE, 2016
Keywords
Computation theory, Importance sampling, Intelligent systems, Monte Carlo methods, Reliability theory, Computation time, Generating capacity, Monte Carlo simulation methods, Multi area power systems, Normal operations, Operating condition, Planning studies, Renewable resource, Electric power system interconnection
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-202153 (URN)10.1109/PESGM.2016.7741943 (DOI)000399937903107 ()2-s2.0-85002406504 (Scopus ID)9781509041688 (ISBN)
Conference
2016 IEEE Power and Energy Society General Meeting, PESGM 2016, 17 July 2016 through 21 July 2016
Note

QC 20170313

Available from: 2017-03-13 Created: 2017-03-13 Last updated: 2017-06-29Bibliographically approved
Organisations

Search in DiVA

Show all publications