New directions in Stochastic Multicriteria Acceptability Analysis

Decisions taken in modern organizations are often multi-dimensional, involving multiple decision makers and several criteria measured on different scales. Multiple Criteria Decision Making (MCDM) methods are designed to analyze and to give recommendations in this kind of situations. Among the numerous MCDM methods, two large families of methods are the multi-attribute utility theory based methods and the outranking methods. Traditionally both method families require exact values for technical parameters and criteria measurements, as well as for preferences expressed as weights. Often it is hard, if not impossible, to obtain exact values. Stochastic Multicriteria Acceptability Analysis (SMAA) is a family of methods designed to help in this type of situations where exact values are not available. Different variants of SMAA allow handling all types of MCDM problems. They support defining the model through uncertain, imprecise, or completely missing values. The methods are based on simulation that is applied to obtain descriptive indices characterizing the problem. In this thesis we present new advances in the SMAA methodology. We present and analyze algorithms for the SMAA-2 method and its extension to handle ordinal preferences. We then present an application of SMAA-2 to an area where MCDM models have not been applied before: planning elevator groups for high-rise buildings. Following this, we introduce two new methods to the family: SMAA-TRI that extends ELECTRE TRI for sorting problems with uncertain parameter values, and SMAA-III that extends ELECTRE III in a similar way. An efficient software implementing these two methods has been developed in conjunction with this work, and is briefly presented in this thesis. The thesis is closed with a comprehensive survey of SMAA methodology including a definition of a unified framework.

Kerrostalon kiinteistösähkönkulutuksen kompensointi aurinkosähköjärjestelmällä

Aurinkopaneeleiden hinta on laskenut reilusti viime vuosien aikana. Hinnan laskun seurauksena aurinkosähköjärjestelmiä on asennettu paljon yksityisiin rakennuksiin sekä Suomessa että muualla maailmassa. Tässä kandidaatintyössä tutkitaan kerrostalon kiinteistösähkönkulutuksen kompensointia aurinkosähköjärjestelmällä. Kompensointia tutkitaan, koska näin saadaan taloudellisesti paras hyöty aurinkosähköjärjestelmästä. Kerrostalon kiinteistösähkönkulutuksella tarkoitetaan talon teknisten järjestelmien kuluttamaa sähköä. Järjestelmän sijoitusta tutkitaan katolle ja parvekekaiteisiin. Katolle sijoitettuna aurinkopaneelien tuotantoa tutkitaan siten, että paneelit ovat asennettu 45° ja 15° tasokulmaan. Aurinkosähköjärjestelmän investoinnin kannattavuutta tutkitaan taloyhtiön näkökulmasta.

Aurinkovoimalaitoksen mitoittaminen suunnitteilla olevaan kerrostaloon

Aurinkopaneelien ja inverttereiden hinnat ovat laskeneet viime vuosina, joten au-rinkosähköstä on tullut kannattava sähköntuotantomuoto kiinteistöille. Tässä kandidaatintyössä kerrotaan, kuinka arvioida suunnitteilla olevan rakennuksen peruskuormaa aurinkopaneeleiden asennuksen näkökulmasta. Voimalaitoksen sijoituskohde sijaitsee Järvenpäässä. Kohteessa on 69 huoneistoa 8 kerroksessa ja yhteiset tilat 9. kerroksessa. Voimalaitoksen kannattavuutta tutkitaan simuloimalla tuotantoja ja arvioimalla kulutusta. Tuotantoja simuloidaan HOMER-ohjelmistolla. Rakennuksen kulutusta arvioidaan suunnittelijoilta saatujen tietojen perusteella, ja vanhempien samankaltaisten kohteiden kulutusten perusteella, jotka saadaan Nuuka-portaalista. Saaduista tuloksista huomataan, että nykyisillä sähkönhinnoilla aurinkopaneelit ovat kannattava investointi, vaikka sähköä tuotettaisiin hieman ylimääräistä, joten paneelit voidaan mitoittaa hieman kulutusta suuremmaksi. Takaisinmaksuaika on noin 20 vuotta. Tulokset ovat linjassa vanhempien tutkimusten kanssa. Tuloksista huomataan, myös että paneeleita jakamalla eri ilmansuuntiin saadaan tuotannon huipputeho pienemmäksi ja samalla tuotanto jakautumaan laajemmalle ajanjaksolle. Paneelien hintojen laskettua on kannattavaa asentaa paneeleja epäedullisempiin suuntiin, täten saadaan tuotantoa ajoitettua mahdollisesti paremmin kulutus-ta vastaavaksi. Mitoituksen voi tarkistaa rakennuksen valmistuttua, sillä raken-nuksesta tullaan mittaamaan paneeleiden tuottama sähkö ja kohteen kiinteistösähkönkulutus.

Toimintamalli asuinkiinteistö öljyvahingon hoitamiseksi

Pienkiinteistöjen öljyvahingot ovat viime vuosina lisääntyneet. Tämän työn tarkoituksena on luoda öljyvahingon torjuntaan ja jälkihoitoon osallistuvalle urakoitsijalle toimintamalli asuinkiinteistön öljyvahingon hoitamiseksi. Mallin halutaan erityisesti kuvaavan öljyvahingon hoitoon osallistuvien viranomaisten ja muiden tahojen vastuita ja velvollisuuksia. Työn tavoitteena on myös tunnistaa pienkiinteistöissä tapahtuvat öljyvahinkotyypit sekä niille altistavat riskitekijät. Öljyn päästäminen ympäristöön sekä öljyn käsittely ja varastointi niin, että siitä aiheutuu öljyvahingon vaara, kielletään laissa. Vahinkojen torjumiseksi on annettu määräyksiä muun muassa öljylämmityslaitteistojen turvallisuutta koskien. Asuinkiinteistöjen öljyvahingot liittyvät yleensä öljysäiliön täyttötilanteisiin. Vahinkojen syynä on usein säiliön ja sen varusteiden puutteellisuus tai huono kunto. Asuinrakennusten lämmitykseen käytetään kevyttä polttoöljyä. Maahan joutuessaan polttoöljy imeytyy sora- ja hiekkamaahan nopeasti, jolloin vaarana on öljyn kulkeutuminen pohjaveteen ja vesistöihin. Asuinkiinteistön öljyvahingossa öljyä joutuu usein myös rakenteisiin. Öljyvahingosta tulee ilmoittaa aina hätäkeskukseen. Vastuu öljyvahinkojen torjunnasta kuuluu alueelliselle pelastustoimelle. Torjuntatoimiin osallistuu usein myös urakoitsija. Jos vahinkokohdetta ei torjuntatoimin saada kunnostettua, alueellinen ympäristökeskus voi määrätä puhdistamisesta vastuussa olevan selvittämään pilaantuneen alueen laajuuden ja puhdistamistarpeen sekä toteuttamaan mahdollisen kunnostuksen. Pilaantuneen maaperän kunnostus voidaan toteuttaa massan vaihtona tai paikan päällä maata kaivamatta. Likaantuneiden rakenteiden saneerausta tarvitaan sisäilman hajuhaittojen poistamiseksi. Öljyvahingon kustannukset voivat nousta hyvinkin suuriksi. Ensisijainen vastuu niistä kuuluu vahingonaiheuttajalle.

The effects of welding heat input on the usability of high strength steels in welded structures

High strength steel (HSS) has been in use in workshops since the 1980s. At that time, the significance of the term HSS differed from the modern conception as the maximum yield strength of HSSs has increased nearly every year. There are three different ways to make HSS. The first and oldest method is QT (quenched and tempered) followed by the TMCP (thermomechanical controlled process) and DQ (direct quenching) methods. This thesis consists of two parts, the first of which part introduces the research topic and discusses welded HSS structures by characterizing the most important variables. In the second part of the thesis, the usability of welded HSS structures is examined through a set of laboratory tests. The results of this study explain the differences in the usability of the welded HSSs made by the three different methods. The results additionally indicate that usage of different HSSs in the welded structures presumes that manufacturers know what kind of HSS they are welding. As manufacturers use greater strength HSSs in welded structures, the demands for welding rise as well. Therefore, during the manufacturing process, factors such as heat input, cooling time, weld quality, and more must be under careful observation.

Identification of Some Additional Loss Components in High-Power Low-Voltage Permanent Magnet Generators

Permanent magnet generators (PMG) represent the cutting edge technology in modern wind mills. The efficiency remains high (over 90%) at partial loads. To improve the machine efficiency even further, every aspect of machine losses has to be analyzed. Additional losses are often given as a certain percentage without providing any detailed information about the actual calculation process; meanwhile, there are many design-dependent losses that have an effect on the total amount of additional losses and that have to be taken into consideration. Additional losses are most often eddy current losses in different parts of the machine. These losses are usually difficult to calculate in the design process. In this doctoral thesis, some additional losses are identified and modeled. Further, suggestions on how to minimize the losses are given. Iron losses can differ significantly between the measured no-load values and the loss values under load. In addition, with embedded magnet rotors, the quadrature-axis armature reaction adds losses to the stator iron by manipulating the harmonic content of the flux. It was, therefore, re-evaluated that in salient pole machines, to minimize the losses and the loss difference between the no-load and load operation, the flux density has to be kept below 1.5 T in the stator yoke, which is the traditional guideline for machine designers. Eddy current losses may occur in the end-winding area and in the support structure of the machine, that is, in the finger plate and the clamping ring. With construction steel, these losses account for 0.08% of the input power of the machine. These losses can be reduced almost to zero by using nonmagnetic stainless steel. In addition, the machine housing may be subjected to eddy current losses if the flux density exceeds 1.5 T in the stator yoke. Winding losses can rise rapidly when high frequencies and 10–15 mm high conductors are used. In general, minimizing the winding losses is simple. For example, it can be done by dividing the conductor into transposed subconductors. However, this comes with the expense of an increase in the DC resistance. In the doctoral thesis, a new method is presented to minimize the winding losses by applying a litz wire with noninsulated strands. The construction is the same as in a normal litz wire but the insulation between the subconductors has been left out. The idea is that the connection is kept weak to prevent harmful eddy currents from flowing. Moreover, the analytical solution for calculating the AC resistance factor of the litz-wire is supplemented by including an end-winding resistance in the analytical solution. A simple measurement device is developed to measure the AC resistance in the windings. In the case of a litz-wire with originally noninsulated strands, vacuum pressure impregnation (VPI) is used to insulate the subconductors. In one of the two cases studied, the VPI affected the AC resistance factor, but in the other case, it did not have any effect. However, more research is needed to determine the effect of the VPI on litz-wire with noninsulated strands. An empirical model is developed to calculate the AC resistance factor of a single-layer formwound winding. The model includes the end-winding length and the number of strands and turns. The end winding includes the circulating current (eddy currents that are traveling through the whole winding between parallel strands) and the main current. The end-winding length also affects the total AC resistance factor.

The influence of high cable penetration in distribution networks on earth fault currents and the operation of relay protection.

Recent Storms in Nordic countries were a reason of long power outages in huge territories. After these disasters distribution networks' operators faced with a problem how to provide adequate quality of supply in such situation. The decision of utilization cable lines rather than overhead lines were made, which brings new features to distribution networks. The main idea of this work is a complex analysis of medium voltage distribution networks with long cable lines. High value of cable’s specific capacitance and length of lines determine such problems as: high values of earth fault currents, excessive amount of reactive power flow from distribution to transmission network, possibility of a high voltage level at the receiving end of cable feeders. However the core tasks was to estimate functional ability of the earth fault protection and the possibility to utilize simplified formulas for operating setting calculations in this network. In order to provide justify solution or evaluation of mentioned above problems corresponding calculations were made and in order to analyze behavior of relay protection principles PSCAD model of the examined network have been created. Evaluation of the voltage rise in the end of a cable line have educed absence of a dangerous increase in a voltage level, while excessive value of reactive power can be a reason of final penalty according to the Finish regulations. It was proved and calculated that for this networks compensation of earth fault currents should be implemented. In PSCAD models of the electrical grid with isolated neutral, central compensation and hybrid compensation were created. For the network with hybrid compensation methodology which allows to select number and rated power of distributed arc suppression coils have been offered. Based on the obtained results from experiments it was determined that in order to guarantee selective and reliable operation of the relay protection should be utilized hybrid compensation with connection of high-ohmic resistor. Directional and admittance based relay protection were tested under these conditions and advantageous of the novel protection were revealed. However, for electrical grids with extensive cabling necessity of a complex approach to the relay protection were explained and illustrated. Thus, in order to organize reliable earth fault protection is recommended to utilize both intermittent and conventional relay protection with operational settings calculated by the use of simplified formulas.