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Felicetti, R., Albuquerque, V. M. & Lundin, U. (2024). An alternative Run-Up Strategy for Salient Pole Wound Field Synchronous Machines. IEEE Open Journal of Industrial Applications, 5, 15-28
Open this publication in new window or tab >>An alternative Run-Up Strategy for Salient Pole Wound Field Synchronous Machines
2024 (English)In: IEEE Open Journal of Industrial Applications, ISSN 2644-1241, Vol. 5, p. 15-28Article in journal (Refereed) Published
Abstract [en]

Salient pole wound field synchronous motors find many industrial applications thanks to their favorable characteristics: reactive power regulation, stiff mechanical characteristic and overall outstanding efficiency. Nevertheless, their competitiveness towards the induction motors, especially for medium and small power sizes, depends crucially on their capability to be asynchronously started as well. Regrettably, the asynchronous run-up of a synchronous motor can be sometimes very problematic because of thermal issues, torsional vibrations and grid voltage disturbances. This paper presents an alternative method of starting salient pole wound field synchronous machines by activating the field winding in a special manner, which makes it possible to mitigate the three problems at once. The suggested method is validated through a 2D finite elements simulation and by starting a 60 kVA prototype generator. The requirements for the application of the proposed run-up strategy are critically discussed together with related pros and cons.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2024
Keywords
asynchronous start, run-up, reluctance torque, salient pole rotor, synchronous motor, torque ripple
National Category
Engineering and Technology Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-510186 (URN)10.1109/ojia.2024.3352134 (DOI)001150701500001 ()
Available from: 2023-08-25 Created: 2023-08-25 Last updated: 2024-03-05Bibliographically approved
Strömme Mattsson, A., Lundin, U. & Billstein, M. (2023). A concept to ensure spill discharge capacity during grid blackout and flooding. In: Symposium “Management for Safe Dams” - 91st Annual ICOLD Meeting. S3-B Hydrology & Hydraulics – Design.: . Paper presented at Symposium “Management for Safe Dams” - 91st Annual ICOLD Meeting. S3-B Hydrology & Hydraulics – Design. 11-15 June 2023, Gothenburg, Sweden.
Open this publication in new window or tab >>A concept to ensure spill discharge capacity during grid blackout and flooding
2023 (English)In: Symposium “Management for Safe Dams” - 91st Annual ICOLD Meeting. S3-B Hydrology & Hydraulics – Design., 2023Conference paper, Published paper (Refereed)
Abstract [en]

The core of dam safety is to safely store and discharge water and thereby prevent uncontrolled release of water. Excess water, e.g. in a flooding situation, is commonly discharged via different types of spillways (gated, weirs, surface, bottom outlets etc.).

The turbine discharge is typically not included in the capacity as flooding scenarios could cause a grid-blackout rendering the turbine incapable of operating.

The paper will describe a project that has tested island operation of a hydropower unit equipped with a developed dump-load device. The dump-load device will allow the unit to operate even during a black-out without risk for failure of the unit and thus assure the discharge capacity via the waterways connected to the unit. Stable operation is verified in the tests and this opens up for the turbine discharge to be included in the total discharge capacity of a facility. A cost-benefit analysis of the suggested solution and a brief description of the past and planned development of the device will be given. In addition to the extra discharge capacity, the new system can also be used to reduce the risk for surge during start- and stop sequences.

Implementation of the system in two different facilities, with different purpose, is planned and details on the coming installations and the technical solutions around them will be given.

National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-505185 (URN)
Conference
Symposium “Management for Safe Dams” - 91st Annual ICOLD Meeting. S3-B Hydrology & Hydraulics – Design. 11-15 June 2023, Gothenburg, Sweden
Available from: 2023-06-19 Created: 2023-06-19 Last updated: 2023-06-19
Felicetti, R. & Lundin, U. (2023). A Synchronous Machine Transient Model Based upon an Algebraic Loop Accounting for Nonlinearity and Cross-Magnetization. International Journal of Rotating Machinery, 2023, Article ID 4547086.
Open this publication in new window or tab >>A Synchronous Machine Transient Model Based upon an Algebraic Loop Accounting for Nonlinearity and Cross-Magnetization
2023 (English)In: International Journal of Rotating Machinery, ISSN 1023-621X, E-ISSN 1542-3034, Vol. 2023, article id 4547086Article in journal (Refereed) Published
Abstract [en]

The purpose of this paper is to carry out an alternative to the present transient models for field wound synchronous machines, which is able to take into account the nonlinearity of the magnetic materials as well as the cross-magnetization. After presenting the principal model structures according to the state variables, a model based on two lookup tables for the magnetizing flux linkages is introduced and built step by step. The resulting signal flowchart shows an algebraic loop within the model, where the main flux linkage rapidly converges to its instantaneous value by simple iteration. The proof of this convergence is given for both saturated and unsaturated machine. Even though the proposed model uses the total linkage flux as state variable, as many alternative models do, it does not require the inversion of the current to flux linkage function (i.e., of lookup tables). This can spare a heavy computational task, especially with very large lookup tables. In the proposed model, the computational effort in the worst case scenario is reduced to few iterations (<10). Finally, the nonlinear behavior of the model is verified in four different transient scenarios by comparing its outcomes with those of a linear model for the same test machine.

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2023
Keywords
Synchronous machine, transient, model, non-linearity, cross-magnetizzation
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science
Identifiers
urn:nbn:se:uu:diva-496713 (URN)10.1155/2023/4547086 (DOI)000939654000001 ()
Funder
Energy ResearchSwedish National GridSwedish Energy AgencyLuleå University of TechnologyKTH Royal Institute of TechnologyChalmers University of TechnologyUppsala UniversityLund University
Available from: 2023-02-20 Created: 2023-02-20 Last updated: 2023-09-06Bibliographically approved
Rondon, D., Aidanpää, J.-O., Gustavsson, R., Lundin, U. & Jeppsson, P. (2023). Dynamic model for hydropower generators with floating rotor rim. Mechanical systems and signal processing, 183, Article ID 109645.
Open this publication in new window or tab >>Dynamic model for hydropower generators with floating rotor rim
Show others...
2023 (English)In: Mechanical systems and signal processing, ISSN 0888-3270, E-ISSN 1096-1216, Vol. 183, article id 109645Article in journal (Refereed) Published
Abstract [en]

For rotordynamic analysis of hydropower units, the generator is treated as a rotating rigid body. However, previous studies have confirmed that certain designs of generators are elastic, so the complex geometry of generators cannot be considered rigid. This work produced a model of hydropower generators with floating rotor rims, consisting of a rigid hub and a flexible rotor rim coupled with flexible connections. The model takes into account the influence of centrifugal and Coriolis effects, and the electromagnetic interaction between rotor and stator. The model also reproduces the dynamics of the generator with static and dynamic eccentricities. A generator prototype was employed to test the model, showing its different applications. Once validated by empirical data, this model could be used when designing generators.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Rotordynamics, Magnetic force, Generator model, Hydropower, Dynamic modeling, Curved beam
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-490090 (URN)10.1016/j.ymssp.2022.109645 (DOI)000877355300003 ()
Available from: 2022-12-15 Created: 2022-12-15 Last updated: 2022-12-15Bibliographically approved
Strömme Mattsson, A., Norrlund, P. & Lundin, U. (2023). Electrical dump-loads increasing spill capacity. In: Hydropower R&D days 2023.: . Paper presented at Hydropower R&D days 2023. SVC – Swedish Centre for Sustainable Hydropower 23-24/3 2023, Luleå, Sweden.
Open this publication in new window or tab >>Electrical dump-loads increasing spill capacity
2023 (English)In: Hydropower R&D days 2023., 2023Conference paper, Poster (with or without abstract) (Refereed)
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-499959 (URN)
Conference
Hydropower R&D days 2023. SVC – Swedish Centre for Sustainable Hydropower 23-24/3 2023, Luleå, Sweden
Available from: 2023-04-05 Created: 2023-04-05 Last updated: 2023-06-19
Fregelius, M. & Lundin, U. (2023). Performance Evaluation of a Supercapacitor Based Synthetic Inertia System Using Frequency Locked Loop and Real-Time Frequency Derivative Estimation. International Journal of Electrical Power & Energy Systems, 144, Article ID 108554.
Open this publication in new window or tab >>Performance Evaluation of a Supercapacitor Based Synthetic Inertia System Using Frequency Locked Loop and Real-Time Frequency Derivative Estimation
2023 (English)In: International Journal of Electrical Power & Energy Systems, ISSN 0142-0615, E-ISSN 1879-3517, Vol. 144, article id 108554Article in journal (Refereed) Published
Abstract [en]

The installation of intermittent renewable energy sources (RESs) are now fast increasing, reducing fossil fuel use. Due to the fact that RESs are typically grid-connected to the power-system via grid following fast-response voltage source converters, the amount of mechanical inertia synchronised in the power system is decreasing. As a result, the power system will be more sensitive to load and generation variations, causing larger frequency fluctuations which, in turn, could result in undesirable load-shedding, or large-scale blackouts. This paper presents a performance evaluation of a concept of emulating virtual inertia via power-electronics and a energy storage unit in terms of a supercapacitor connected to the DC-bus. Simulation and experimental results are presented to validate the proposed combination of frequency estimation and frequency derivative estimation. The paper shows the feasibility of using virtual inertia and how it could be implemented.

Place, publisher, year, edition, pages
Elsevier, 2023
National Category
Signal Processing Control Engineering
Identifiers
urn:nbn:se:uu:diva-437901 (URN)10.1016/j.ijepes.2022.108554 (DOI)000860635900003 ()
Available from: 2021-03-17 Created: 2021-03-17 Last updated: 2022-10-17Bibliographically approved
Felicetti, R., Pérez-Loya, J. J. & Lundin, C. U. (2023). Simulation of Rapid Voltage Edge Related Voltage Surges in Highly Inductive Windings with Frequency Dependent Parameters. Progress in Electromagnetics Research B, 99, 1-21
Open this publication in new window or tab >>Simulation of Rapid Voltage Edge Related Voltage Surges in Highly Inductive Windings with Frequency Dependent Parameters
2023 (English)In: Progress in Electromagnetics Research B, E-ISSN 1937-6472, Vol. 99, p. 1-21Article in journal (Refereed) Published
Abstract [en]

Many static and rotating electric energy converters make use of inductive coils as filters, reactive loads or exciters, where a sudden variation of the magnetizing current can produce severe overvoltage with potential subsequent insulation damage. In some applications the overvoltage is the result of a superposition of travelling voltage waves in a supplying line. Traditional tools for studying such phenomena are based on ordinary differential equations that can heavily handle variable parameters, especially if they change according to the rapidity of the observed overvoltage. In this paper the transient voltage distribution in the excitation winding of a salient pole synchronous generator is simulated by solving the problem entirely in the frequency domain, i.e., without any use of the traditional ordinary differential equations solvers. Thismakesit possible to tune the parameters of a simplified electric model to the frequency response of the studied winding. It is shown that for highly inductive windings a single transmission line model with frequency dependent parameters can reproduce voltage transients very accurately, in a broad interval of frequency, relevant for power electronics and electromagnetic compatibility applications. Furthermore, the paper presents the experimental setup which has been needed for generating the fast varying voltage edges.

Place, publisher, year, edition, pages
The Electromagnetics Academy, 2023
Keywords
choke, distributed parameters circuit, Fourier transform, field winding, fast switching, frequency response analysis, overvoltage, partial discharge, salient pole rotor, synchronous machine
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering with specialization in Systems Analysis
Identifiers
urn:nbn:se:uu:diva-434617 (URN)10.2528/PIERB22122705 (DOI)
Funder
EU, Horizon 2020, 764011
Note

Title in the list of papers of Roberto Felicetti's thesis: Simulation of rapid front edges related voltage surges in highly inductive windings with frequency dependent parameters

Available from: 2021-02-11 Created: 2021-02-11 Last updated: 2023-09-06Bibliographically approved
Laban, D., Norrlund, P. & Lundin, U. (2023). Storage System Design for Improved Primary Frequency Control From Hydropower Units. IEEE transactions on energy conversion, 38(3), 1836-1844
Open this publication in new window or tab >>Storage System Design for Improved Primary Frequency Control From Hydropower Units
2023 (English)In: IEEE transactions on energy conversion, ISSN 0885-8969, E-ISSN 1558-0059, Vol. 38, no 3, p. 1836-1844Article in journal (Refereed) Published
Abstract [en]

The upcoming modifications to the criteria for providing Frequency Containment Reserves (FCR) in the Nordic synchronous area present severe challenges for some hydropower units. By quantifying the difference between the required FCR power response and the actual response provided by the unit, an additional power response from an energy storage system can be specified to augment the hydropower unit, thus securing its participation in FCR in the future. A practical method to control the storage system, by applying a band-pass filter on the negative frequency deviation, is presented in this paper. The method is verified using a set of field measurements from Swedish hydropower units currently providing FCR. It is found that all tested units are able to satisfy the upcoming criteria with the specified storage systems. The optimality of the method is discussed by comparing the storage system power and energy ratings to the theoretical minimum. Obtained power ratings between 3% and 24% of the FCR power, combined with a short storage system duration of up to 2.5 minutes, indicate that the method presents a possible application for high-power and low-energy storage technologies.

Place, publisher, year, edition, pages
IEEE, 2023
Keywords
Control design, energy storage, frequency control, hydroelectric power generation
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-515478 (URN)10.1109/TEC.2023.3269621 (DOI)001081209800031 ()
Available from: 2023-11-07 Created: 2023-11-07 Last updated: 2024-03-27Bibliographically approved
Lundin, U., Jonsson, P. & Facciolo, L. (2023). Using hydropower turbine discharge as a complementary spillway. Journal of Applied Water Engineering and Research, 11(1), 117-126
Open this publication in new window or tab >>Using hydropower turbine discharge as a complementary spillway
2023 (English)In: Journal of Applied Water Engineering and Research, ISSN 2324-9676, E-ISSN 2324-9676, Vol. 11, no 1, p. 117-126Article in journal (Refereed) Published
Abstract [en]

Spillways are very important dam safety devices that can discharge large amounts of water to prevent over-topping a dam. However, spillways are expensive to build and have operational issues. This paper is a report from a test of a system capable of discharging the full turbine flow even in the absence of an external power grid absorbing the electrical power. Instead the power is dissipated in a local load. The scope of the tests is to verify the use of the discharge capacity of the turbine under continuous operation as spillway flow for emergency discharge from a Hydropower reservoir. A dumpload consisting of a hot water electrode boiler cooled by water taken from the turbine spiral case was used as a local load. The results show long-term stability of using a local load and turbine discharge as an electrical alternative to building additional traditional spillways to increase spillway capacity from a hydropower reservoir.

Place, publisher, year, edition, pages
Taylor & Francis Group, 2023
Keywords
spillway, hydropower, dam safety, electrode boiler, turbine discharge
National Category
Water Engineering
Identifiers
urn:nbn:se:uu:diva-501609 (URN)10.1080/23249676.2022.2087774 (DOI)000814693300001 ()
Funder
StandUpVattenfall AB
Available from: 2023-05-10 Created: 2023-05-10 Last updated: 2023-05-10Bibliographically approved
Felicetti, R. & Lundin, U. (2022). Salient pole electrical machine. Patent- och registreringsverket SE 545283.
Open this publication in new window or tab >>Salient pole electrical machine
2022 (English)Patent (Other (popular science, discussion, etc.))
Abstract [en]

An electrical machine (1) comprises a stator (20) having armature windings (24), a rotor (10) having salient poles (12) and being rotably arranged with respect to the stator (20), and a rotor excitation system (30). The rotor excitation system (30) has a rotor winding arrangement (14), a rotor power supply (34) for exciting the salient poles (12), and a rotor driving unit (32) configured to control currents provided to the rotor winding arrangement (14). In a first operation mode, the rotor excitation system (30) is sconfigured for providing a rotating magnetic field  by supplying alternating currents to the rotor winding arrangement (14), while the armature windings (24) being short-circuited or closed on external resistors. A method for operating an electrical machine is also disclosed.

Keywords
asynchonous start, salient pole rotor, synchronous machine, thermal stress, torque ripple
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-509883 (URN)
Patent
Patent- och registreringsverket SE 545283 (2022-06-20)
Available from: 2023-08-23 Created: 2023-08-23 Last updated: 2023-09-06Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-9412-4383

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