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Synchronised measurements on hydropower units during power system startup
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. (Hydropower)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. (Hydropower)
(English)In: Hydro Review Worldwide, ISSN 1072-9542Article in journal (Refereed) Submitted
Abstract [en]

During a recent full-scale blackstart test of the Nordic power system, measurements of electrical and mechanical quantities using both phasor measurement units (PMUs) and synchronised local acquisition devices was performed. This paper describes the measurement system and discusses a few important considerations for synchronised measurements in multiple hydropower stations. One generator's response to a \unit[100]{MW} load step is shown and an observed subsynchronous oscillation is discussed. It is shown that comprehensive measurements using multiple synchronised data acquisition devices can be performed using off-the-shelf hardware and existing infrastructure. The findings show the danger of assuming that all the interesting information is found at the fundamental frequency.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:uu:diva-182157OAI: oai:DiVA.org:uu-182157DiVA: diva2:558596
Available from: 2012-10-04 Created: 2012-10-04 Last updated: 2017-12-07Bibliographically approved
In thesis
1. Hydropower generator and power system interaction
Open this publication in new window or tab >>Hydropower generator and power system interaction
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

After decades of routine operation, the hydropower industry faces new challenges. Large-scale integration of other renewable sources of generation in the power system accentuates the role of hydropower as a regulating resource. At the same time, an extensive reinvestment programme has commenced where many old components and apparatus are being refurbished or replaced. Introduction of new technical solutions in existing power plants requires good systems knowledge and careful consideration. Important tools for research, development and analysis are suitable mathematical models, numerical simulation methods and laboratory equipment. This doctoral thesis is devoted to studies of the electromechanical interaction between hydropower units and the power system. The work encompasses development of mathematical models, empirical methods for system identification, as well as numerical and experimental studies of hydropower generator and power system interaction. Two generator modelling approaches are explored: one based on electromagnetic field theory and the finite element method, and one based on equivalent electric circuits. The finite element model is adapted for single-machine infinite-bus simulations by the addition of a network equivalent, a mechanical equation and a voltage regulator. Transient simulations using both finite element and equivalent circuit models indicate that the finite element model typically overestimates the synchronising and damping properties of the machine. Identification of model parameters is performed both numerically and experimentally. A complete set of equivalent circuit parameters is identified through finite element simulation of standard empirical test methods. Another machine model is identified experimentally through frequency response analysis. An extension to the well-known standstill frequency response (SSFR) test is explored, which involves measurement and analysis of damper winding quantities. The test is found to produce models that are suitable for transient power system analysis. Both experimental and numerical studies show that low resistance of the damper winding interpole connections are vital to achieve high attenuation of rotor angle oscillations. Hydropower generator and power system interaction is also studied experimentally during a full-scale startup test of the Nordic power system, where multiple synchronised data acquisition devices are used for measurement of both electrical and mechanical quantities. Observation of a subsynchronous power oscillation leads to an investigation of the torsional stability of hydropower units. In accordance with previous studies, hydropower units are found to be mechanically resilient to subsynchronous power oscillations. However, like any other generating unit, they are dependent on sufficient electrical and mechanical damping. Two experimentally obtained hydraulic damping coefficients for a large Francis turbine runner are presented in the thesis.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 119 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 978
Keyword
Amortisseur windings, applied voltage test, automatic voltage regulators, damper windings, damping torque, empirical modelling, equivalent circuits, excitation control, finite element method, hydropower generators, power system restoration, power system stability, synchronous machines, self excitation, shaft torque amplification, short circuit test, single machine infinite bus, slip test, standstill frequency response test, subsynchronous oscillations, synchronising torque, synchronous generators, torsional interaction.
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-182188 (URN)978-91-554-8486-6 (ISBN)
Public defence
2012-11-16, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2012-10-26 Created: 2012-10-04 Last updated: 2013-01-23

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Bladh, Johan

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