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Assessment of energy storage systems for power system applications based on equivalent circuit modeling
KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering. (Energy storage for smart grid)ORCID iD: 0000-0002-3070-9059
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Climate change triggered the rethinking of our current energy system. A restructuring is necessary and in progress with the goal to improve our energy supplychain in efficiency and sustainability. This has led to the increased use of renewable energy sources such as solar and wind power. In 2017 wind power surpassed all other sources, including oil, nuclear, coal, except gas in terms of total installed capacity. Renewable energy sources became an integral part in our energy systemand will continue to grow in the future. However, what is often forgotten ist hat these sources introduce high variability in the provision of power. Variability implies a lack of control over the availability of electricity, which seldom matches with the concurrent demand. Energy storages have been highlighted as a viable solution in managing arising imbalances and maintaining the security of supply. Nevertheless, numerous technologies and application possibilities exist, each unique in their characteristics and requirements. Not every energy storage works in every situation, which naturally raises the question: How can we choose the optimal storage for any application?

To answer this question we developed an unified model approach for all energy storages based on the equivalent circuit model. The key idea is to provide a direct way of comparing and assessing energy storages, i.e., by simulating and analyzing their performances for different applications. Differences in performance become visible in investigating the dynamic behavior. We proposed a general model, which effectively represents energy storages of different types (electrical, mechanical, hydraulicetc.) and includes their main characteristics (also non-linearity). Secondly, the proposed models have been validated through an experimental setup to test energy storages under changing operations. Subsequently, a sizing routine has been implemented to optimally size an energy storage system for any type of application. Based on this approach the energy storages can be easily compared and important key parameters such as efficiency, rated power, energy capacity etc., can be derived. Finally, the proposed models and methods are applied to various power system applications. A suitability index is introduced to measure the qualification of an individual energy storage for the selected applications. Alternatively, an evaluation method based on fuzzy logic has been explored. Both suitability index and fuzzy logic can effectively determine and rank the suitability of energy storages.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019. , p. 69
Series
TRITA-EECS-AVL ; 2019:3
Keywords [en]
Energy storage system; Assessment; Equivalent circuit model; Suitability;
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering; Energy Technology
Identifiers
URN: urn:nbn:se:kth:diva-240089ISBN: 978-91-7873-053-7 (print)OAI: oai:DiVA.org:kth-240089DiVA, id: diva2:1269847
Public defence
2019-01-25, 4301 Kollegiesalen, Brinellvägen 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Projects
STandUP for Energy
Note

QC 20181211

Available from: 2018-12-14 Created: 2018-12-11 Last updated: 2018-12-14Bibliographically approved
List of papers
1. On the physical system modelling of energy storages as equivalent circuits with parameter description for variable load demand (Part I)
Open this publication in new window or tab >>On the physical system modelling of energy storages as equivalent circuits with parameter description for variable load demand (Part I)
2017 (English)In: Journal of Energy Storage, ISSN 2352-152X, Vol. 13, p. 73-84Article in journal (Refereed) Published
Abstract [en]

Energy storages take a key role in electrical energy balancing in our power grid in respect to the increasing utilization of renewable energies. Assessing the effectiveness of energy storages and finding the optimal use under varying load conditions is essential which requires accurate modelling. This study highlights the equivalent circuit modelling approach for different energy storages. The model parameters R, L, C and Ub define the storage system in question allowing us to analyse storage devices under varying load conditions. Technical assessment criteria (efficiency, response time etc.) of energy storages can also be deducted from these models. Energy storages feature non-linear characteristics which are reflected in variable model parameters.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Batteries, Capacitors, Energy storage, Equivalent circuits, Flywheels, Physical system modelling, Pumped hydro storage, Smart grid, Ultracapacitors
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-212218 (URN)10.1016/j.est.2017.05.015 (DOI)000417183300008 ()2-s2.0-85022081882 (Scopus ID)
Note

QC 20170821

Available from: 2017-08-21 Created: 2017-08-21 Last updated: 2018-12-18
2. Optimal energy storage sizing using equivalent circuit modelling for prosumer applications (Part II)
Open this publication in new window or tab >>Optimal energy storage sizing using equivalent circuit modelling for prosumer applications (Part II)
2018 (English)In: Journal of Energy Storage, Vol. 18, p. 1-15Article in journal, Editorial material (Refereed) Published
Abstract [en]

An optimal system design indirectly implies efficient use of available resources, i.e., minimum investment to achieve the desired outcome. An increased demand of energy storages highlights the importance of efficient useand optimal storage sizing. However, the variety of available and newly developed storage technologies complicates decision-making in choosing the appropriate technology to the compatible application. The characterizationof storage types extends to the inherent dynamic behavior and technical limitations, which is imperativefor storage system design. This paper proposes a brute-force method of optimal storage system sizing based onthe equivalent circuit modeling while considering storage's operation constraints. The sizing routine is applied to a set of different energy storage technologies (lead-acid, Li-ion, vanadium-redox flow battery, double-layercapacitor, flywheel) to balance the energy demand of a single-family building supported by a 3.36 kWpeak photovoltaic system. This case focuses on the energy management application of energy storages. Additionally, asuitability index is introduced to determine the applicability of the investigated storages in reference to an ideal case.

Keywords
Optimization, Energy storage, Brute-force method, Equivalent circuit
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-227174 (URN)10.1016/j.est.2018.04.015 (DOI)000439496500001 ()2-s2.0-85046370323 (Scopus ID)
Projects
StandUp for Energy
Note

QC 20180612

Available from: 2018-05-03 Created: 2018-05-03 Last updated: 2018-12-11Bibliographically approved
3. Experimental validation of a general energy storage modelling approach(Part III)
Open this publication in new window or tab >>Experimental validation of a general energy storage modelling approach(Part III)
2018 (English)In: Journal of Energy Storage, E-ISSN 2352-152X, Vol. 20, p. 542-550Article in journal (Refereed) Published
Abstract [en]

Current challenges in the electric grid progression demand energy storages to cope with any imbalances betweensupply and demand side. Application possibilities of energy storages are numerous, but the requirements varyfrom case to case. However, not every storage technology operates equally to be useful in any situation. In fact,the feasibility of energy storages depend on their technical characteristics, i.e., for example efficiency, responsetimes, power rating and capacity for a selected application. Comparing and assessing different storage options isimperative for decision-making, which requires an in-depth understanding of the technology and its dynamics.Hence, a general model approach of energy storages as equivalent circuit models has been proposed to unify andanalyze storages of different physical backgrounds. This allows a more direct and intuitive evaluation of energystorages tested in a specific application. This paper focuses on the experimental validation of energy storages(ultra-capacitor, li-ion battery, lead-acid battery and flywheel) to be uniformly described in one general model. Asimple and budget friendly experimental setup to test the storages is designed.

Keywords
Energy storage, Li-ion battery, Lead-acid battery, Double-layer capacitor, Flywheel, Equivalent circuit
National Category
Energy Systems
Research subject
Electrical Engineering; Energy Technology
Identifiers
urn:nbn:se:kth:diva-238589 (URN)10.1016/j.est.2018.09.023 (DOI)000451147100052 ()2-s2.0-85055878495 (Scopus ID)
Projects
STand UP for Energy
Note

QC 20181106

Available from: 2018-11-05 Created: 2018-11-05 Last updated: 2018-12-18Bibliographically approved
4. Technical assessment of energy storage systems for power system applications via suitability index approach (Part IV)
Open this publication in new window or tab >>Technical assessment of energy storage systems for power system applications via suitability index approach (Part IV)
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Energy storage systems provide several benets and services in optimizing the power grid's reliability, effciency and safety. However, the feasibility of energy storage systems varies dependent on the requirements of the applications. Technical limitations in design and type of the storage technology prevents a single storage type to perform equally well in all situations. Hence,it is essential to compare and measure the energy storages' usefulness anddetermine their optimal use. To address this issue this study introduces an indexing approach to evaluate the suitability of energy storages for power system applications. Four different energy storages (double-layer capacitor, flywheel, lead-acid battery, lithium-ion battery) are tested for four typical energy storage applications (frequency regulation, voltage support, capacity firming and energy time-shift). The suitability index allows a simple and intuitive way to compare and rank the suitability of energy storages.

Keywords
Energy storage; Li-ion battery; Lead-acid battery; Electric double-layer capacitor; Flywheel; Assessment; Power system application; Suitability index
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-240088 (URN)
Projects
STandUp for Energy
Note

QC 20181211

Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2018-12-11Bibliographically approved
5. Suitability analysis of Fuzzy Logic as an evaluation method for the selection of energy storage technologies in Smart Grid applications
Open this publication in new window or tab >>Suitability analysis of Fuzzy Logic as an evaluation method for the selection of energy storage technologies in Smart Grid applications
2015 (English)In: Smart Electric Distribution Systems and Technologies (EDST), 2015 International Symposium on, IEEE , 2015Conference paper, Published paper (Refereed)
Abstract [en]

Energy storage systems are a key element in the development of the smart grid. The complexity of the power grid necessitates energy storages to provide various services with each having distinct requirements. Each energy storage technology comes with its own unique characteristics, which makes it difficult to select suitable energy storages for specified applications. This paper reviews the suitability of using Fuzzy Logic as a selection method. The main objective of this study is to compare the results of the multi-criteria analysis with the present experience and literature of energy storage applications.

Place, publisher, year, edition, pages
IEEE, 2015
Keywords
Energy Storage, Fuzzy Logic, Multicriteria Evaluation Method, Smart Grid Application
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering; Planning and Decision Analysis
Identifiers
urn:nbn:se:kth:diva-173722 (URN)10.1109/SEDST.2015.7315251 (DOI)000380614000075 ()2-s2.0-84964430195 (Scopus ID)978-1-4799-7735-2 (ISBN)
External cooperation:
Conference
International Symposium on Smart Electric Distribution Systems and Technologies (EDST) CIGRE SC C6 Colloquium, Vienna, Austria - September 8-11, 2015
Funder
StandUp
Note

QC 20151116

Available from: 2015-09-17 Created: 2015-09-17 Last updated: 2018-12-11Bibliographically approved
6. On the development of an equivalent electrical circuit model for energy storages for smart grid applications
Open this publication in new window or tab >>On the development of an equivalent electrical circuit model for energy storages for smart grid applications
2016 (English)In: Innovative Smart Grid Technologies - Asia (ISGT-Asia), 2016 IEEE, Institute of Electrical and Electronics Engineers (IEEE), 2016, p. 75-80Conference paper, Published paper (Refereed)
Abstract [en]

Energy storages are indispensable in regard to the development of the smart grid with increasing fluctuating power generation. A valid choice of energy storages is important to ensure the efficiency of the system and selected application. This study describes an initial approach to model energy storage systems as an equivalent circuit. This model is capable of analyzing different load scenarios and simulating the storage's behavior in dependence of three circuit components, i.e., resistance, inductance, and capacitance. These model parameters define the storage system and can be used to test existing storage devices or find an optimal setting for selected load conditions.The model is tested in a load scenario with a residential building supported by photovoltaic generation.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2016
Keywords
Energy Storage, Smart Grid, Simulation, Physical System Modelling, Photovoltaic, Battery, Flywheel
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering; Energy Technology
Identifiers
urn:nbn:se:kth:diva-199602 (URN)10.1109/ISGT-Asia.2016.7796364 (DOI)000391851500013 ()2-s2.0-85010053556 (Scopus ID)978-1-5090-4303-3 (ISBN)
Conference
2016 IEEE Innovative Smart Grid Technologies - Asia (ISGT-Asia)
Funder
StandUp, 76390
Note

QC 20170113

Available from: 2017-01-10 Created: 2017-01-10 Last updated: 2018-12-11Bibliographically approved

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Citation style
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  • modern-language-association-8th-edition
  • vancouver
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Output format
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