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Publications (10 of 357) Show all publications
Nycander, E. & Söder, L. (2019). Comparison of stochastic and deterministic security constrained optimal power flow under varying outage probabilities. In: 2019 IEEE Milan PowerTech, PowerTech 2019: . Paper presented at 2019 IEEE Milan PowerTech, PowerTech 2019; Milan; Italy; 23 June 2019 through 27 June 2019. Institute of Electrical and Electronics Engineers (IEEE), Article ID 8810833.
Open this publication in new window or tab >>Comparison of stochastic and deterministic security constrained optimal power flow under varying outage probabilities
2019 (English)In: 2019 IEEE Milan PowerTech, PowerTech 2019, Institute of Electrical and Electronics Engineers (IEEE), 2019, article id 8810833Conference paper, Published paper (Refereed)
Abstract [en]

Increasing penetration of renewables and focus on cost efficiency means that power systems are operated closer to security limits. It has been suggested that the traditional N-l approach to security is unsatisfactory as it does not consider the likelihood and severity of contingencies. In this paper we investigate a stochastic version of security-constrained optimal power flow (S-SCOPF), which considers outage probabilities when deciding the optimal dispatch. Both a priori dispatch costs and realized real time costs are considered to evaluate the usefulness of the S-SCOPF a s opposed to the deterministic SCOPF (D-SCOPF). For low outage probabilities the S-SCOPF gives lower total costs, achieved by reducing the security for contingency situations. For high outage probabilities the two methods give the same dispatch. The robustness of the S-SCOPF to errors in the outage probability is also investigated. Underestimating the true outage probability results in the S-SCOPF giving higher total costs.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2019
Keywords
OPF, Probabilistic security, SCOPF
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-262637 (URN)10.1109/PTC.2019.8810833 (DOI)2-s2.0-85072337547 (Scopus ID)9781538647226 (ISBN)
Conference
2019 IEEE Milan PowerTech, PowerTech 2019; Milan; Italy; 23 June 2019 through 27 June 2019
Note

QC 20191017

Available from: 2019-10-17 Created: 2019-10-17 Last updated: 2019-10-17Bibliographically approved
Herre, L., Matusevičius, T., Olauson, J. & Söder, L. (2019). Exploring Wind Power Prognosis Data on Nord Pool: The Case of Sweden and Denmark. IET Renewable Power Generation
Open this publication in new window or tab >>Exploring Wind Power Prognosis Data on Nord Pool: The Case of Sweden and Denmark
2019 (English)In: IET Renewable Power Generation, ISSN 1752-1416, E-ISSN 1752-1424, ISSN 1752-1416Article in journal (Refereed) Published
Abstract [en]

A good understanding of forecast errors is imperative for greater penetration of wind power, as it can facilitate planning and operation tasks. Oftentimes, public data is used for system studies without questioning or verifying its origin. In this paper, we propose a methodology to verify public data with the example of wind power prognosis published by Nord Pool. We focus on Swedish data and identify a significant bias that increases over the forecast horizon. In order to explore the origin of this bias, we first compare against Danish forecast and then describe the underlying structure behind the submission processes of this data. Based on the balance settlement structure, we reveal that Swedish "wind power prognoses" on Nord Pool are in fact rather wind production plans than technical forecasts. We conclude with the recommendation for improved communication and transparency with respect to terminology of public data on Nord Pool. We stress the importance for the research community to check publicly available input data before further use. Furthermore, the root-mean-square error and the spatio-temporal correlation between the errors in the bidding areas at different horizons is presented. Even with this compromised data, a stronger correlation is identified in neighbouring areas.

Keywords
wind power forecasts, forecast anaylsis, vindkraftspognoser, analys av vindkraftsprognoser
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Energy Systems
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-241639 (URN)10.1049/iet-rpg.2018.5086 (DOI)000462942900006 ()2-s2.0-85063728250 (Scopus ID)
Note

QC 20190124

Available from: 2019-01-24 Created: 2019-01-24 Last updated: 2019-04-29Bibliographically 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
Divshali, P. H. & Söder, L. (2019). Improving PV Dynamic Hosting Capacity Using Adaptive Controller for STATCOMs. IEEE transactions on energy conversion, 34(1), 415-425
Open this publication in new window or tab >>Improving PV Dynamic Hosting Capacity Using Adaptive Controller for STATCOMs
2019 (English)In: IEEE transactions on energy conversion, ISSN 0885-8969, E-ISSN 1558-0059, Vol. 34, no 1, p. 415-425Article in journal (Refereed) Published
Abstract [en]

High penetrations of renewable energy sources (RES) in distribution grids lead to new challenges in voltage regulation. These challenges are not just limited to the steady-state voltage rise, but they are extended to rapid voltage changes due to wind speed variations and moving clouds, casting shadows on photovoltaic panels. According to EN50160 in low-voltage (LV) grids, the steady-state voltage should not exceed 1.1 pu (static characteristic), and rapid voltage changes should be kept less than 0.05 pu (dynamic characteristic). These two characteristics may limit the maximum amount of RES that can be installed in LV grids, called, respectively, the static hosting capacity (SHC) and dynamic hosting capacity (DHC). Although existing research just evaluated SHC in distribution grids, high-penetrated RES grids can be faced with such large voltage changes, which cause a smaller DHC than the SHC. This paper studies both SHC and DHC in distribution grids and proposes an adaptive controller for static synchronous compensators to regulate the steady-state and dynamic voltage while avoiding the unnecessary increase in the reactive power. The simulation results in some German distribution grids show considerable effects of the proposed adaptive controller on improving both SHC and DHC.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2019
Keywords
Distribution grids, dynamic voltage regulation, hosting capacity, reactive power, renewable energy sources (RESs)
National Category
Environmental Engineering
Identifiers
urn:nbn:se:kth:diva-247822 (URN)10.1109/TEC.2018.2873057 (DOI)000460332600041 ()
Note

QC 20190327

Available from: 2019-03-27 Created: 2019-03-27 Last updated: 2019-06-11Bibliographically approved
Nycander, E., Söder, L., Eriksson, R. & Hamon, C. (2019). Minimising wind power curtailments using OPF considering voltage stability. The Journal of Engineering (18), 5064-5068
Open this publication in new window or tab >>Minimising wind power curtailments using OPF considering voltage stability
2019 (English)In: The Journal of Engineering, ISSN 1872-3284, E-ISSN 2051-3305, no 18, p. 5064-5068Article in journal (Refereed) Published
Abstract [en]

As the amount of wind power in power systems has increased, it has become necessary to curtail wind power in some high-penetration situations. In order to assess the need for curtailment arising from voltage stability considerations the authors develop a security constrained optimal power flow (SCOPF) for minimising the expected curtailment. The authors find that with a very high wind penetration and wind farms operating at unity power factor curtailment becomes necessary to satisfy voltage limits. In this case, the optimal solution in the studied system is to curtail at a single bus rather than curtailing by a smaller amount at several buses. However, allowing for reactive power production from wind farms reduces the need for curtailments.

Place, publisher, year, edition, pages
INST ENGINEERING TECHNOLOGY-IET, 2019
Keywords
load flow, wind power plants, wind power, reactive power, power system security, power factor, minimising wind power curtailments, OPF considering voltage stability, power systems, high-penetration situations, voltage stability considerations, optimal power flow, expected curtailment, high wind penetration, wind farms, unity power factor curtailment, voltage limits, reactive power production
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-260206 (URN)10.1049/joe.2018.9371 (DOI)000482590000074 ()
Note

QC 20190930

Available from: 2019-09-30 Created: 2019-09-30 Last updated: 2019-09-30Bibliographically approved
Tomaszewski, M., Stanković, S., Leisse, I. & Söder, L. (2019). Minimization of Reactive Power Exchange at the DSO/TSO interface: Öland case. 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 8905712.
Open this publication in new window or tab >>Minimization of Reactive Power Exchange at the DSO/TSO interface: Öland case
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 8905712Conference paper, Published paper (Refereed)
Abstract [en]

A rising penetration of renewable energy sources in electric power grids is both a challenge and an opportunity to utilize its potential to stabilize operation of future power systems. Bi-directional flows between distribution and transmission systems can cause significant problems with keeping the voltages and reactive power in grids within permissible levels. This paper addresses the problem of reactive power exchange between the distribution system of Öland and the mainland Swedish electricity grid. Wind turbine generators with the capacity that highly exceeds total demand in Öland, are used to minimize absolute reactive power exchanged at the point of connection. This is done by applying droop control functions for reactive support to the wind turbines. Results indicate that the controllability of the reactive power support from wind turbine generators can keep the reactive power flow minimized at the point of connection and simultaneously diminish the active power losses in the system. The analysis in this paper has been done using the PSS/E software.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2019
Keywords
Droop Control, Power Flow Analysis, Reactive Power, Smart Grids
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-266052 (URN)10.1109/ISGTEurope.2019.8905712 (DOI)2-s2.0-85075880334 (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 20191220

Available from: 2019-12-20 Created: 2019-12-20 Last updated: 2019-12-20Bibliographically approved
Herre, L., Dalton, J. & Söder, L. (2019). Optimal Day-Ahead Energy and Reserve Bidding Strategy of a Risk-Averse Electric Vehicle Aggregator in the Nordic Market. In: : . Paper presented at 13th IEEE PowerTech 2019, 23-27 June, Milano, Italy. IEEE
Open this publication in new window or tab >>Optimal Day-Ahead Energy and Reserve Bidding Strategy of a Risk-Averse Electric Vehicle Aggregator in the Nordic Market
2019 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Electric vehicles (EV) can be considered as energy storage with availability, energy and capacity constraints that can provide flexibility to the power system in the form of balancing products when aggregated. In this paper, we develop a two-stage stochastic optimization problem that maximizes the profit of a risk-averse EV aggregator for bids on the day ahead in both energy and Frequency Containment Reserve (FCR) markets. Unidirectional charging is examined, while we take into account uncertainty from prices and vehicle availability. Case studies are carried out in different Nordic bidding areas based on historical EV charging data. We identify a strong temporal alignment of EV availability and high FCR-N prices. Results show that consumption is shifted largely towards early hours of the morning. When compared to a reference cost of charging case, up to 50% of the cost of charging can be recovered in Norway, and 100% in Sweden.

Place, publisher, year, edition, pages
IEEE, 2019
Keywords
ancillary services, balancing markets, demand side management, electric vehicles
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering; Economics
Identifiers
urn:nbn:se:kth:diva-254616 (URN)10.1109/PTC.2019.8810937 (DOI)2-s2.0-85072317934 (Scopus ID)978-1-5386-4722-6 (ISBN)978-1-5386-4723-3 (ISBN)
Conference
13th IEEE PowerTech 2019, 23-27 June, Milano, Italy
Funder
Swedish Energy Agency
Note

QC 20190710. QC 20191203

Available from: 2019-07-02 Created: 2019-07-02 Last updated: 2019-12-03Bibliographically approved
Lund, P. D., Skytte, K., Bolwig, S., Bolkesjö, T. F., Bergaentzlé, C., Gunkel, P. A., . . . Söder, L. (2019). Pathway analysis of a zero-emission transition in the Nordic-Baltic region. Energies, 12(17), Article ID 3337.
Open this publication in new window or tab >>Pathway analysis of a zero-emission transition in the Nordic-Baltic region
Show others...
2019 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 17, article id 3337Article in journal (Refereed) Published
Abstract [en]

A zero-emission pathway for the Nordic and Baltic region in Europe is described based on the comprehensive policy and scenario analyses, accompanied by energy system modelling. The analyses show that a least-cost strategy would massively employ renewable energy, particularly in the power sector. Through strong coupling across energy sectors and countries, electricity would play a central role in the decarbonization of the main energy sectors. In particular power-to-heat conversion, where heat storage appears important in addition to existing hydropower. Technical and regulatory barriers in front of increased sector coupling and flexibility were identified, and policy measures are proposed to overcome these. In addition to a high carbon price, dynamic tariffs and taxation of electricity would be important to allow market signals for flexibility to reach end-users. A stronger power transmission connection from the Nordics to the mainland-Europe and the United Kingdom would be beneficial for the emission reductions and renewable energy use. The transition pathway analysis points out socio-technical issues such as social acceptance of large-scale new infrastructures (e.g., wind, cables). The energy system optimizations indicate that most of the investments needed for the zero-emission pathway until 2050 would take place already by 2030.

Place, publisher, year, edition, pages
MDPI AG, 2019
Keywords
Decarbonization, Energy transition, Policies, Renewable energy, Sector coupling
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-262516 (URN)10.3390/en12173337 (DOI)000486860500134 ()2-s2.0-85071562401 (Scopus ID)
Note

QC 20191029

Available from: 2019-10-29 Created: 2019-10-29 Last updated: 2019-11-06Bibliographically approved
Söder, L. (2019). The Costs of Decarbonisation: System Costs with High Shares of Nuclear and Renewables -Impact from updated cost assumptions. Stockholm
Open this publication in new window or tab >>The Costs of Decarbonisation: System Costs with High Shares of Nuclear and Renewables -Impact from updated cost assumptions
2019 (English)Report (Other academic)
Abstract [en]

The aim of this study is to perform a sensitivity analysis concerning impact from assumed investment costs of the NEA/OECD report “The Costs of Decarbonisation: System Costs with High Shares of Nuclear and Renewables” from 2019. A study of this type, i.e. technical-economic analysis, has a set-up as: [input data] => [simulation method]  => [output results]. The output results then completely depend on used input data and simulation method. The question is then what happens with other types of data assumptions.

The aim is to study the changes from assumed investment and O&M costs, since the main ones used in the report are not reflective of neither actual, nor forecasted costs.

We will start the analysis by trying to duplicate the results of the original NEA/OECD report in order to ensure our methodology is consistent with theirs. This is a challenge as their data and methodology is semi-transparent and not clearly defined. However, the central data, as total cost, can be replicated. Here in Chapter 3 we summarize their data and results. In Chapter 4 we then try to duplicate their methodology and results and compare it to the NEA/OECD results, in particular the total costs for their different cases. The more up to date and forecasted investment and O&M costs data is presented in Chapter 5.  Chapter 6 gives the results of applying these data sets and compares and contrasts it with the NEA/OECD results. References are found in chapter 7. The summary of the findings is found in chapter 2.

All calculations are done within Excel, and the program can be downloaded.

Place, publisher, year, edition, pages
Stockholm: , 2019. p. 28
National Category
Engineering and Technology
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-251689 (URN)
Note

QC 20190520

Available from: 2019-05-19 Created: 2019-05-19 Last updated: 2019-05-20Bibliographically approved
Dabar, O. A., Awaleh, M. O., Kirk-Davidoff, D., Olauson, J., Söder, L. & Awaleh, S. I. (2019). Wind resource assessment and economic analysis for electricity generation in three locations of the Republic of Djibouti. Energy, 185, 884-894
Open this publication in new window or tab >>Wind resource assessment and economic analysis for electricity generation in three locations of the Republic of Djibouti
Show others...
2019 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 185, p. 884-894Article in journal (Refereed) Published
Abstract [en]

In the Republic of Djibouti, due to increasing electricity demands, the government has planned to increase power supply by using renewable resources such as geothermal, solar and wind energy. This work presents the first wind resource assessment in the Republic of Djibouti using measured wind speed data for the period of three years by meteorological stations at eight locations. The results confirmed that three of the eight locations (i.e. GaliMa-aba, Ghoubbet and Bada Wein) have the best resource, with mean annual wind speeds of more than 6.0 m/s. Wind simulations using NCEP-CFSR and ERA5 models reanalysis shows that the seasonal variations are stable between different years and are broadly consistent with the observed wind speed. The feasibility of three wind farms with total capacity of 275 MW at GaliMa-aba, Ghoubbet and Bada Wein is examined. Using the WindPRO program and two commercial wind turbines in according to IEC 61400-1 design criteria, the electricity generation were technically assessed. These wind farms can produce 1073 GWh of electricity per year, approximately equal to Djibouti's expected average annual electrical demand in 2030. The economic evaluation using the present value cost (PVC) method estimate that the generation cost per kWh at these locations varies from 7.03 US.$ cent/kWh to 9.67 US.$ cent/kWh. Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2019
Keywords
Djibouti, Wind energy, WindPRO, NCEP-CFSR, ERA5 reanalysis, Cost analysis
National Category
Energy Engineering
Research subject
Energy Technology
Identifiers
urn:nbn:se:kth:diva-260994 (URN)10.1016/j.energy.2019.07.107 (DOI)000484869400072 ()2-s2.0-85069710284 (Scopus ID)
Note

QC 20191010

Available from: 2019-10-10 Created: 2019-10-10 Last updated: 2019-11-26Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-8189-2420

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