Reaaliaikaisen PMU-mittaustiedon hyödyntäminen voimajärjestelmän valvonnassa

Tämä työ on tehty Fingrid Oyj:lle. Työn tavoitteena oli tutkia, miten reaaliaikaista PMU-mittaustietoa voidaan hyödyntää voimajärjestelmän valvonnassa. Voimajärjestelmän dynaamisia ilmiöitä ovat jännite- ja kulmastabiilius. Työssä tutkittiin voimajärjestelmän kulmastabiiliutta PSS/E-ohjelmalla simuloitujen mittaustulosten perusteella. Fouriermuunnoksen tulokset osoittavat, että huonoiten vaimeneva taajuuskomponentti on 0,3 Hz taajuus. Lisäksi tiedetään, että huonosti vaimeneva taajuuskomponentti rajoittaa siirtokapasiteettia. Voimajärjestelmän stabiiliutta voidaan esittää Wide Area Monitoring -järjestelmien (WAMS) avulla. WAMS perustuu Phasor Measurement -laitteen (PMU) reaaliaikaiseen mittaustekniikkaan. Jännitteen vaihekulman mittaaminen mahdollistaa voimajärjestelmän tilan määrittämisen reaaliajassa. Työssä on esitelty Fingridin käytössä oleva WAMS ja lisäksi esitelty kolmen eri laitetoimittajan WAMS:n rakennetta ja operaattorin käyttöön tarkoitettuja käyttöliittymiä. WAMS:n rakenteet ovat pääpiirteittäin samanlaisia, mutta stabiiliuden visuaalisessa esittämisessä on eroja. PMU -mittaustietoja on mahdollista tuoda käytönvalvontajärjestelmään erillisellä tiedonsiirtoprotokollalla. PMU-mittaustiedon hyödyntäminen käytönvalvontajärjestelmän toimintaaluenäytöllä mahdollistaa verkon tilan esittämisen reaaliajassa. Roottorin kulmastabiilius esitetään Fingridin käytönvalvontajärjestelmässä vaihekulmaerojen avulla ja työssä on esitetty, kuinka vaihekulmaeron arvolla on vaikutus tehonsiirtoon. Vaihekulmaeron arvo kuvaa vian jälkeisen tehoheilahtelun voimakkuutta. PMU-mittaustiedon esittäminen antaa operaattorille selkeämmän kuvan ylläpitää tehonsiirto turvallisella tasolla ja epästabiilin heilahtelun havainnoiminen vähentää suurhäiriön riskiä. Tulevaisuudessa siirtoverkon kehittyessä tarvitaan operaattorin käyttöön myös nopeita stabiilisuutta esittäviä työkaluja.

Uuden Venäjän koordinaatit

Kirjallisuusarvostelu

Surface characterization of chemically modified fiber, wood and paper

Inorganic-organic sol-gel hybrid coatings can be used for improving and modifying properties of wood-based materials. By selecting a proper precursor, wood can be made water repellent, decay-, moisture- or UV-resistant. However, to control the barrier properties of sol-gel coatings on wood substrates against moisture uptake and weathering, an understanding of the surface morphology and chemistry of the deposited sol-gel coatings on wood substrates is needed. Mechanical pulp is used in production of wood-containing printing papers. The physical and chemical fiber surface characteristics, as created in the chosen mechanical pulp manufacturing process, play a key role in controlling the properties of the end-use product. A detailed understanding of how process parameters influence fiber surfaces can help improving cost-effectiveness of pulp and paper production. The current work focuses on physico-chemical characterization of modified wood-based materials with surface sensitive analytical tools. The overall objectives were, through advanced microscopy and chemical analysis techniques, (i) to collect versatile information about the surface structures of Norway spruce thermomechanical pulp fiber walls and understand how they are influenced by the selected chemical treatments, and (ii) to clarify the effect of various sol-gel coatings on surface structural and chemical properties of wood-based substrates. A special emphasis was on understanding the effect of sol-gel coatings on the water repellency of modified wood and paper surfaces. In the first part of the work, effects of chemical treatment on micro- and nano-scale surface structure of 1st stage TMP latewood fibers from Norway spruce were investigated. The chemicals applied were buffered sodium oxalate and hydrochloric acid. The outer and the inner fiber wall layers of the untreated and chemically treated fibers were separately analyzed by light microscopy, atomic force microscopy and field-emission scanning electron microscopy. The selected characterization methods enabled the demonstration of the effect of different treatments on the fiber surface structure, both visually and quantitatively. The outer fiber wall areas appeared as intact bands surrounding the fiber and they were clearly rougher than areas of exposed inner fiber wall. The roughness of the outer fiber wall areas increased most in the sodium oxalate treatment. The results indicated formation of more surface pores on the exposed inner fiber wall areas than on the corresponding outer fiber wall areas as a result of the chemical treatments. The hydrochloric acid treatment seemed to increase the surface porosity of the inner wall areas. In the second part of the work, three silane-based sol-gel hybrid coatings were selected in order to improve moisture resistance of wood and paper substrates. The coatings differed from each other in terms of having different alkyl (CH3–, CH3-(CH2)7–) and fluorocarbon (CF3–) chains attached to the trialkoxysilane sol-gel precursor. The sol-gel coatings were deposited by a wet coating method, i.e. spraying or spreading by brush. The effect of solgel coatings on surface structural and chemical properties of wood-based substrates was studied by using advanced surface analyzing tools: atomic force microscopy, X-ray photoelectron spectroscopy and time-of-flight secondary ion spectroscopy. The results show that the applied sol-gel coatings, deposited as thin films or particulate coatings, have different effects on surface characteristics of wood and wood-based materials. The coating which has a long hydrocarbon chain (CH3-(CH2)7–) attached to the silane backbone (octyltriethoxysilane) produced the highest hydrophobicity for wood and wood-based materials.

Ring Dark Solitons in Toroidal Bose-Einstein Condensates

In this Thesis, we study various aspects of ring dark solitons (RDSs) in quasi-two-dimensional toroidally trapped Bose-Einstein condensates, focussing on atomic realisations thereof. Unlike the well-known planar dark solitons, exact analytic expressions for RDSs are not known. We address this problem by presenting exact localized soliton-like solutions to the radial Gross-Pitaevskii equation. To date, RDSs have not been experimentally observed in cold atomic gases, either. To this end, we propose two protocols for their creation in experiments. It is also currently well known that in dimensions higher than one, (ring) dark solitons are susceptible, in general, to an irreversible decay into vortex-antivortex pairs through the snake instability. We show that the snake instability is caused by an unbalanced quantum pressure across the soliton's notch, linking the instability to the Bogoliubov-de Gennes spectrum. In particular, if the angular symmetry is maintained (or the toroidal trapping is restrictive enough), we show that the RDS is stable (long-lived with a lifetime of order seconds) in two dimensions. Furthermore, when the decay does take place, we show that the snake instability can in fact be reversible, and predict a previously unknown revival phenomenon for the original (many-)RDS system: the soliton structure is recovered and all the point-phase singularities (i.e. vortices) disappear. Eventually, however, the decay leads to an example of quantum turbulence; a quantum example of the laminar-to-turbulent type of transition.

Photon Upconverting Nanophosphors: Unique Reporters for Optical Biosensing

Upconversion photoluminescence is a unique property of mostly certain inorganic materials, which are capable of converting low-energy infrared radiation into a higher-energy emission at visible wavelengths. This anti-Stokes shift enables luminescence detection without autofluorescence, which makes the upconverting materials a highly suitable reporter technology for optical biosensing applications. Furthermore, they exhibit long luminescence lifetime with narrow bandwidths also at the optical window of biomaterials enabling luminescence measurements in challenging sample matrices, such as whole blood. The aim of this thesis was to study the unique properties and the applicability of nano-sized upconverting phosphors (UCNPs) as reporters in biosensing applications. To render the inorganic nanophosphors water-dispersible and biocompatible, they were subjected to a series of surface modifications starting with silica-encapsulation and ending with a bioconjugation step with an analyte-recognizing biomolecule. The paramagnetism of the lanthanide dopants in the nanophosphors was exploited to develop a highly selective separation method for the UCNP-bioconjugates based on the magnetic selectivity of the high gradient magnetic separation (HGMS) system. The applicability of the nano-sized UCNPs as reporters in challenging sample matrices was demonstrated in two homogeneous sensing applications based on upconversion resonance energy transfer (UC-RET). A chemosensor for intracellular pH was developed exploiting UC-RET between the UCNP and a fluorogenic pH-sensitive dye with strongly increasing fluorescence intensity in decreasing pH. The pH-independent emission of the UCNPs at 550 nm was used for referencing. The applicability of the pH-nanosensor for intracellular pH measurement was tested in HeLa cells, and the acidic pH of endosomes could be detected with a confocal fluorescence microscope. Furthermore, a competitive UC-RET-based assay for red blood cell folic acid was developed for the measurement of folate directly from a whole blood sample. The optically transparent window of biomaterials was used in both the excitation and the measurement of the UC-RET sensitized emission of a near-infrared acceptor dye to minimize sample absorption, and the anti-Stokes detection completely eliminated the Stokes-shifted autofluorescence. The upconversion photoluminescence efficiency is known to be dependent on crystallite size, because the increasing surface-to-volume ratio of nano-sized UCNPs renders them more susceptible to quenching effects of the environment than their bulk counterpart. Water is known to efficiently quench the luminescence of lanthanide dopants. In this thesis, the quenching mechanism of water was studied using luminescence decay measurements. Water was found to quench the luminescence of UCNPs by increasing the non-radiative relaxation of the excited state of Yb3+ sensitizer ion, which had a very strong quenching effect on upconversion luminescence intensity.

Coolability of porous core debris beds : Effects of bed geometry and multi-dimensional flooding

This thesis addresses the coolability of porous debris beds in the context of severe accident management of nuclear power reactors. In a hypothetical severe accident at a Nordic-type boiling water reactor, the lower drywell of the containment is flooded, for the purpose of cooling the core melt discharged from the reactor pressure vessel in a water pool. The melt is fragmented and solidified in the pool, ultimately forming a porous debris bed that generates decay heat. The properties of the bed determine the limiting value for the heat flux that can be removed from the debris to the surrounding water without the risk of re-melting. The coolability of porous debris beds has been investigated experimentally by measuring the dryout power in electrically heated test beds that have different geometries. The geometries represent the debris bed shapes that may form in an accident scenario. The focus is especially on heap-like, realistic geometries which facilitate the multi-dimensional infiltration (flooding) of coolant into the bed. Spherical and irregular particles have been used to simulate the debris. The experiments have been modeled using 2D and 3D simulation codes applicable to fluid flow and heat transfer in porous media. Based on the experimental and simulation results, an interpretation of the dryout behavior in complex debris bed geometries is presented, and the validity of the codes and models for dryout predictions is evaluated. According to the experimental and simulation results, the coolability of the debris bed depends on both the flooding mode and the height of the bed. In the experiments, it was found that multi-dimensional flooding increases the dryout heat flux and coolability in a heap-shaped debris bed by 47–58% compared to the dryout heat flux of a classical, top-flooded bed of the same height. However, heap-like beds are higher than flat, top-flooded beds, which results in the formation of larger steam flux at the top of the bed. This counteracts the effect of the multi-dimensional flooding. Based on the measured dryout heat fluxes, the maximum height of a heap-like bed can only be about 1.5 times the height of a top-flooded, cylindrical bed in order to preserve the direct benefit from the multi-dimensional flooding. In addition, studies were conducted to evaluate the hydrodynamically representative effective particle diameter, which is applied in simulation models to describe debris beds that consist of irregular particles with considerable size variation. The results suggest that the effective diameter is small, closest to the mean diameter based on the number or length of particles.

Chemical changes in biomass during torrefaction

Torrefaction is moderate thermal treatment (~200-300 °C) of biomass in an inert atmosphere. The torrefied fuel offers advantages to traditional biomass, such as higher heating value, reduced hydrophilic nature, increased its resistance to biological decay, and improved grindability. These factors could, for instance, lead to better handling and storage of biomass and increased use of biomass in pulverized combustors. In this work, we look at several aspects of changes in the biomass during torrefaction. We investigate the fate of carboxylic groups during torrefaction and its dependency to equilibrium moisture content. The changes in the wood components including carbohydrates, lignin, extractable materials and ashforming matters are also studied. And at last, the effect of K on torrefaction is investigated and then modeled. In biomass, carboxylic sites are partially responsible for its hydrophilic characteristic. These sites are degraded to varying extents during torrefaction. In this work, methylene blue sorption and potentiometric titration were applied to measure the concentration of carboxylic groups in torrefied spruce wood. The results from both methods were applicable and the values agreed well. A decrease in the equilibrium moisture content at different humidity was also measured for the torrefied wood samples, which is in good agreement with the decrease in carboxylic group contents. Thus, both methods offer a means of directly measuring the decomposition of carboxylic groups in biomass during torrefaction as a valuable parameter in evaluating the extent of torrefaction. This provides new information to the chemical changes occurring during torrefaction. The effect of torrefaction temperature on the chemistry of birch wood was investigated. The samples were from a pilot plant at Energy research Center of the Netherlands (ECN). And in that way they were representative of industrially produced samples. Sugar analysis was applied to analyze the hemicellulose and cellulose content during torrefaction. The results show a significant degradation of hemicellulose already at 240 °C, while cellulose degradation becomes significant above 270 °C torrefaction. Several methods including Klason lignin method, solid state NMR and Py-GC-MS analyses were applied to measure the changes in lignin during torrefaction. The changes in the ratio of phenyl, guaiacyl and syringyl units show that lignin degrades already at 240 °C to a small extent. To investigate the changes in the extractives from acetone extraction during torrefaction, gravimetric method, HP-SEC and GC-FID followed by GC-MS analysis were performed. The content of acetone-extractable material increases already at 240 °C torrefaction through the degradation of carbohydrate and lignin. The molecular weight of the acetone-extractable material decreases with increasing the torrefaction temperature. The formation of some valuable materials like syringaresinol or vanillin is also observed which is important from biorefinery perspective. To investigate the change in the chemical association of ash-forming elements in birch wood during torrefaction, chemical fractionation was performed on the original and torrefied birch samples. These results give a first understanding of the changes in the association of ashforming elements during torrefaction. The most significant changes can be seen in the distribution of calcium, magnesium and manganese, with some change in water solubility seen in potassium. These changes may in part be due to the destruction of carboxylic groups. In addition to some changes in water and acid solubility of phosphorous, a clear decrease in the concentration of both chlorine and sulfur was observed. This would be a significant additional benefit for the combustion of torrefied biomass. Another objective of this work is studying the impact of organically bound K, Na, Ca and Mn on mass loss of biomass during torrefaction. These elements were of interest because they have been shown to be catalytically active in solid fuels during pyrolysis and/or gasification. The biomasses were first acid washed to remove the ash-forming matters and then organic sites were doped with K, Na, Ca or Mn. The results show that K and Na bound to organic sites can significantly increase the mass loss during torrefaction. It is also seen that Mn bound to organic sites increases the mass loss and Ca addition does not influence the mass loss rate on torrefaction. This increase in mass loss during torrefaction with alkali addition is unlike what has been found in the case of pyrolysis where alkali addition resulted in a reduced mass loss. These results are important for the future operation of torrefaction plants, which will likely be designed to handle various biomasses with significantly different contents of K. The results imply that shorter retention times are possible for high K-containing biomasses. The mass loss of spruce wood with different content of K was modeled using a two-step reaction model based on four kinetic rate constants. The results show that it is possible to model the mass loss of spruce wood doped with different levels of K using the same activation energies but different pre-exponential factors for the rate constants. Three of the pre-exponential factors increased linearly with increasing K content, while one of the preexponential factors decreased with increasing K content. Therefore, a new torrefaction model was formulated using the hemicellulose and cellulose content and K content. The new torrefaction model was validated against the mass loss during the torrefaction of aspen, miscanthus, straw and bark. There is good agreement between the model and the experimental data for the other biomasses, except bark. For bark, the mass loss of acetone extractable material is also needed to be taken into account. The new model can describe the kinetics of mass loss during torrefaction of different types of biomass. This is important for considering fuel flexibility in torrefaction plants.

Tulevaisuuden lähtökohdista kansanvallan kolmiliittoon. Kansallinen Edistyspuolue ja kansallisen eheytymisen politiikka 1919–1939.

Kansallista Edistyspuoluetta ja sen toimijoita maailmansotien välisen Suomen sisäpolitiikassa tarkasteleva väitöstutkimus paneutuu puolueen kansallista eheytymistä ajaneen poliittisen linjan taustoihin, muodostumiseen ja toteutumiseen maailmansotien välisenä aikana vuosina 1919-1939. Vahvasti aineistopohjainen ja lähdekriittinen poliittisen historian tutkimus keskittyy parlamentaarisiin toimijoihin, poliittiseen kenttään ja näiden tuottamiin aineistoihin, kuten edistyspuolueen ja sen toimijoiden arkistoihin, lehdistöön ja valtiopäiväpöytäkirjoihin. Tutkimus selvittää, millainen oli edistyspuolueen kansallisen eheytymisen linja, mihin sillä pyrittiin, miten sitä toteutettiin ja miten se toteutui. Kansainvälisen vertailun kautta tutkimuksessa luodaan myös kuva suomalaisesta liberalismista ja liberalistista. Joulukuussa 1918 perustettu Kansallinen Edistyspuolue oli liberaali puolue, jonka politiikassa korostui erityisesti liberalismin sosiaalinen tulkinta. Puolueen sisäpoliittiseksi linjaksi vastaitsenäistyneessä ja sisällissodan runtelemassa valtiossa muodostui kansallisen eheytymisen edistäminen. Ajatuksen taustalla olivat K. J. Ståhlbergin tulevaisuuden lähtökohtia hahmotelleet artikkelit, jotka julkaistiin Helsingin Sanomissa huhtikuussa 1918 sisällissodan vielä riehuessa. Ståhlbergin mukaan kansalliseen eheytymiseen ei tullut pyrkiä sodan vuoksi vaan siitä huolimatta. Nuorsuomalaiselta puolueelta perityt liberaalit periaatteet täydentyivätkin edistyspuoluelaisessa ajattelussa sisällissodan ja tasavallan puolesta käydyn valtiomuototaistelun avainkokemuksilla. Itsenäisen Suomen ensimmäisiä vuosia hallinneissa keskustahallituksissa kansallista eheytymistä edistettiin sosiaalipoliittisin uudistuksin mm. oppivelvollisuus- ja asutuslakien muodossa. Myös sisällissodan vankien armahdukset olivat osa tätä ohjelmaa. Tutkimus osoittaa, että edistyspuolueen kansallisen eheytymisen politiikan keskeisenä tavoitteena oli poliittisen sovittelun kautta integroida vasemmisto osaksi parlamentaaris-demokraattista järjestelmää. Eheytyspolitiikan todellinen käyttöarvo ja edistyspuolueen poliittiset toimintamahdollisuudet alkoivat kuitenkin heiketä vuoden 1922 eduskuntavaalien jälkeen.Tutkimuksesta käy ilmi, että toteutettu eheytyspolitiikka ja sen osittainen epäonnistuminen näkyivät sekä kommunistien jatkuvana kannatuksena että sisäpoliittisen ilmapiirin oikeistolaistumisena. Tämä kehitys nosti myös edistyspuolueessa esille voimat, jotka suosivat porvariyhteistyötä ohi keskustavasemmistolaisen eheytyspoliittisen linjan. Alkuvuosien jälkeen valtiomuototaistelun koossapitävä voima heikkeni edistyspuolueen sisällä ja 1920-luvun puolivälissä käydyt linjakiistat osoittivat, että osalle puolueen jäsenistä vuoden 1918 puoluevalinnassa keskeisemmässä roolissa oli ollut tasavaltalaisuus kuin vasemmiston integrointi ja kansallinen eheytyminen. Edistyspuolueen johto ei kuitenkaan ollut valmis luopumaan eheytyspoliittisesta linjasta ja sen ympärille luodusta puolueidentiteetistä, joten porvariyhteistyötä kannattanut oikeisto-oppositio päätyi suurelta osin eroamaan puolueesta vuonna 1927. Tutkimus osoittaa, että parlamentarismin rapautuminen ja pienelle yleispuolueelle elintärkeiden yhteistyömahdollisuuksien heikkeneminen luokkapuolueiden puristuksessa johtivat edistyspuolueen kannatuksen alamäkeen sotien välisenä aikana. Se kutistui 26 kansanedustajan keskisuuresta puolueesta vain kuuden edustajan pienpuolueeksi. Puolueidentiteetin vahvuus ja keskeisten toimijoiden puolueen kokoa suurempi poliittinen painoarvo pitivät sen lakkauttamispohdinnoista huolimatta kuitenkin koossa ja kiinni politiikan ytimessä. Oikeistoradikalismin vuodet 1920–1930-lukujen taitteessa olivat edistyspuolueellesekä uhka että mahdollisuus. Tutkimuksessa käy ilmi, että vaikka kommunisminvastaisen kansanliikkeen vaatimukset olivat edistyspuoluelaisten mielestä oikeutettuja, oli kansanliikkeen niiden ajamiseksi omaksumia laittomia ja ulkoparlamentaarisia keinoja vaikea hyväksyä. Eheytyspolitiikan kannalta katsottuna melkotoivottamalta näyttänyt tilanne kääntyi kuitenkin lopulta voitoksi: äärivasemmisto eliminoitiin, äärioikeisto ajautui paitsioon ja tie maltillisen vasemmiston ja keskustan yhteistyölle aukesi jälleen. Tämä johti lopulta vuonna 1937 punamultahallitukseen ja kansanvallan kolmiliittoon Kansallisen Edistyspuolueen, SDP:n ja Maalaisliiton kesken. Kokemus siitä, että itsenäisyys oli alati uhattuna, toi suomalaiseen liberalismiin varsin nationalistisia piirteitä, joita eurooppalaisten veljespuolueiden ohjelmista ei löydy. Liberalismiin usein liitetty mielleyhtymä sen kosmopoliittisesta, kansallisvaltioita ylittävästä luonteesta jäi Suomessa sotien välisenä aikana nationalismin ja itäisen naapurin luoman uhan varjoon. Suomen sisäpoliittinen tilanne ja geopoliittinen asema loivat vaatimuksen vahvasta kansallisesta yhtenäisyydestä. Suomalainen liberalismi määrittyikin eurooppalaisia vastineitaan voimakkaammin nuorta valtiota hallinneen kansallisuusajattelun, itsesäilytysvaiston ja kansallisen eheyden vaatimusten kautta. Tutkimuksessa todetaan, että edistyspuolueen eheytyspoliittisen linjan muotoutumista ja toteutumista vuosien 1919‒1939 aikana voi pitää idealismin voittona realismista. Lukuun ottamatta reformipolitiikan vuosia edistyspuolueen pitäytyminen valitulla linjalla näyttäytyi poliittisten toimintamahdollisuuksien kannalta katsottuna ajoittain jopa epärealistiselta. Koko sotien välistä aikaa tarkastellessa voikin todeta, että se, minkä edistyspuolue poliittisten päämäärien saavuttamisen valossa voitti, sen se menetti kannatusluvuissa.