Forecasting of wind speeds and directions with artificial neural networks

In this master’s thesis, wind speeds and directions were modeled with the aim of developing suitable models for hourly, daily, weekly and monthly forecasting. Artificial Neural Networks implemented in MATLAB software were used to perform the forecasts. Three main types of artificial neural network were built, namely: Feed forward neural networks, Jordan Elman neural networks and Cascade forward neural networks. Four sub models of each of these neural networks were also built, corresponding to the four forecast horizons, for both wind speeds and directions. A single neural network topology was used for each of the forecast horizons, regardless of the model type. All the models were then trained with real data of wind speeds and directions collected over a period of two years in the municipal region of Puumala in Finland. Only 70% of the data was used for training, validation and testing of the models, while the second last 15% of the data was presented to the trained models for verification. The model outputs were then compared to the last 15% of the original data, by measuring the mean square errors and sum square errors between them. Based on the results, the feed forward networks returned the lowest generalization errors for hourly, weekly and monthly forecasts of wind speeds; Jordan Elman networks returned the lowest errors when used for forecasting of daily wind speeds. Cascade forward networks gave the lowest errors when used for forecasting daily, weekly and monthly wind directions; Jordan Elman networks returned the lowest errors when used for hourly forecasting. The errors were relatively low during training of the models, but shot up upon simulation with new inputs. In addition, a combination of hyperbolic tangent transfer functions for both hidden and output layers returned better results compared to other combinations of transfer functions. In general, wind speeds were more predictable as compared to wind directions, opening up opportunities for further research into building better models for wind direction forecasting.

Myyntitiimin organisaatiokansalaisuus: taustatekijät ja korrelaatio taloudelliseen tulokseen : Case: Top-Sport Oy

Jatkuvassa muutoksessa olevan työelämän yksi suurimpia haasteita on työntekijöiden työssä jaksaminen ja työhyvinvointi. Vaikka haasteisiin onkin jo puututtu ja esimerkiksi työhyvinvointia mitataan monissa työpaikoissa, olosuhteiden parantaminen vielä asia erikseen. Osasyy siihen, että työhyvinvoinnin parantamiseen ei keskitytä tarpeeksi saattaa olla se, että työhyvinvoinnin merkitystä taloudellisen menestyksen kannalta ei ole pystytty tieteellisesti todistamaan. Tässä tutkielmassa tutkitaan myyntitiimien sisäisiä ominaisuuksia ja erityisesti myyntitiimien organisaatiokansalaisuutta, sen taustatekijöitä ja niiden lineaarista riippuvuussuhdetta myyntitiimin taloudelliseen tulokseen. Tutkielman päätarkoituksena on pyrkiä selvittämään löytyykö myyntitiimin taloudellisen tuloksen ja myyntitiimin organisaatiokansalaisuuden ja sen taustatekijöiden välillä suhdetta, mikä voisi selittää myyntitiimin työhyvinvoinnin ja taloudellisen tuloksen välistä mekaniikkaa. Pääongelma onkin, miten organisaatiokansalaisuus ja sen taustatekijät myyntitiimissä korreloivat tiimin taloudelliseen tuloksen kanssa? Tutkielman teoriaosuudessa keskitytään myyntitiimien teoriaan ja organisaatiokansalaisuuden teoriaan. Tiimien käyttö kaikissa organisaatioissa on yleistynyt valtavasti viime vuosikymmenien aikana. Tiimeistä on tullut organisaatioihin toimintatapa, jolla asiat saadaan toimimaan yksikön funktiosta tai toimialasta huolimatta. Tutkielman toinen teoria liittyy organisaatiokansalaisuuteen. Organisaatiokansalaisuus on johtamisen kirjallisuudesta löytyvä ilmiö, mikä merkitsee työntekijöiden sellaista vapaaehtoista käytöstä, minkä lopputulemana organisaatio menestyy paremmin. Tutkielmassa empiirisessä osassa keskitytään tutkimaan vapaa-ajan vaatteita ja välineitä myyvän Top-Sport Oy:n myyntitiimejä. Tutkimus on toteutettu laadullisena case-tutkimuksena. Tutkimukseen osallistuivat kaikki organisaation 24 myyntitiimiä. Aineisto kerättiin kyselylomakkeen avulla. Kyselylomakkeen sisältö johdettiin tutkielman teoreettisessa viitekehyksessä. Aineiston analysoimisessa käytettiin hyväksi taloustieteen kvantitatiivisia menetelmiä, jonka jälkeen tuloksia tulkittiin teoreettisen viitekehyksen ja tutkijan näkemyksen pohjalta. Tutkielman keskeisinä tuloksina löydettiin, että organisaatiokansalaisuus on positiivisesti korreloiva monien ilmiön taustatekijöiden kuten esimiestyytyväisyyden, ilmapiirin ja sitoutumisen kanssa. Toisaalta organisaatiokansalaisuuden löydettiin korreloivan negatiivisesti myyntitiimin jäsenten työsuhteen keston ja erityisesti myyntitiimin taloudellisen tuloksen kanssa. Johtopäätöksenä tutkielmasta voidaan sanoa, että yleisesti positiivisena ilmiönä pidettyä organisaatiokansalaisuutta tulisi alkaa tarkastella kriittisemmin, koska tutkielman tulosten mukaan organisaatiokansalaisuus ei ole yksiselitteisesti positiivinen ilmiö ainakaan myyntitiimin taloudelliseen tuloksen näkökulmasta.

Testing FCM technique for the wind energy scenarios in Finland

In the latter days, human activities constantly increase greenhouse gases emissions in the atmosphere, which has a direct impact on a global climate warming. Finland as European Union member, developed national structural plan to promote renewable energy generation, pursuing the aspects of Directive 2009/28/EC and put it on the sharepoint. Finland is on a way of enhancing national security of energy supply, increasing diversity of the energy mix. There are plenty significant objectives to develop onshore and offshore wind energy generation in country for a next few decades, as well as another renewable energy sources. To predict the future changes, there are a lot of scenario methods developed and adapted to energy industry. The Master’s thesis explored “Fuzzy cognitive maps” approach in scenarios developing, which captures expert’s knowledge in a graphical manner and using these captures for a raw scenarios testing and refinement. There were prospects of Finnish wind energy development for the year of 2030 considered, with aid of FCM technique. Five positive raw scenarios were developed and three of them tested against integrated expert’s map of knowledge, using graphical simulation. The study provides robust scenarios out of the preliminary defined, as outcome, assuming the impact of results, taken after simulation. The thesis was conducted in such way, that there will be possibilities to use existing knowledge captures from expert panel, to test and deploy different sets of scenarios regarding to Finnish wind energy development.

Simulation of wind powered hydraulic heating system

The objective of this master’s thesis was to design and simulate a wind powered hydraulic heating system that can operate independently in remote places where the use of electricity is not possible. Components for the system were to be selected in such a way that the conditions for manufacture, use and economic viability are the as good as possible. Savonius rotor was chosen for wind turbine, due to its low cut in speed and robust design. Savonius rotor produces kinetic energy in wide wind speed range and it can withstand high wind gusts. Radial piston pump was chosen for the flow source of the hydraulic heater. Pump type was selected due to its characteristics in low rotation speeds and high efficiency. Volume flow from the pump is passed through the throttle orifice. Pressure drop over the orifice causes the hydraulic oil to heat up and, thus, creating thermal energy. Thermal energy in the oil is led to radiator where it conducts heat to the environment. The hydraulic heating system was simulated. For this purpose a mathematical models of chosen components were created. In simulation wind data gathered by Finnish meteorological institute for 167 hours was used as input. The highest produced power was achieved by changing the orifice diameter so that the rotor tip speed ratio follows the power curve. This is not possible to achieve without using electricity. Thus, for the orifice diameter only one, the optimal value was defined. Results from the simulation were compared with investment calculations. Different parameters effecting the investment profitability were altered in sensitivity analyses in order to define the points of investment profitability. Investment was found to be profitable only with high average wind speeds.

Large-eddy simulation of wind flows over complex terrains for wind energy applications

Wind energy has obtained outstanding expectations due to risks of global warming and nuclear energy production plant accidents. Nowadays, wind farms are often constructed in areas of complex terrain. A potential wind farm location must have the site thoroughly surveyed and the wind climatology analyzed before installing any hardware. Therefore, modeling of Atmospheric Boundary Layer (ABL) flows over complex terrains containing, e.g. hills, forest, and lakes is of great interest in wind energy applications, as it can help in locating and optimizing the wind farms. Numerical modeling of wind flows using Computational Fluid Dynamics (CFD) has become a popular technique during the last few decades. Due to the inherent flow variability and large-scale unsteadiness typical in ABL flows in general and especially over complex terrains, the flow can be difficult to be predicted accurately enough by using the Reynolds-Averaged Navier-Stokes equations (RANS). Large- Eddy Simulation (LES) resolves the largest and thus most important turbulent eddies and models only the small-scale motions which are more universal than the large eddies and thus easier to model. Therefore, LES is expected to be more suitable for this kind of simulations although it is computationally more expensive than the RANS approach. With the fast development of computers and open-source CFD software during the recent years, the application of LES toward atmospheric flow is becoming increasingly common nowadays. The aim of the work is to simulate atmospheric flows over realistic and complex terrains by means of LES. Evaluation of potential in-land wind park locations will be the main application for these simulations. Development of the LES methodology to simulate the atmospheric flows over realistic terrains is reported in the thesis. The work also aims at validating the LES methodology at a real scale. In the thesis, LES are carried out for flow problems ranging from basic channel flows to real atmospheric flows over one of the most recent real-life complex terrain problems, the Bolund hill. All the simulations reported in the thesis are carried out using a new OpenFOAM® -based LES solver. The solver uses the 4th order time-accurate Runge-Kutta scheme and a fractional step method. Moreover, development of the LES methodology includes special attention to two boundary conditions: the upstream (inflow) and wall boundary conditions. The upstream boundary condition is generated by using the so-called recycling technique, in which the instantaneous flow properties are sampled on aplane downstream of the inlet and mapped back to the inlet at each time step. This technique develops the upstream boundary-layer flow together with the inflow turbulence without using any precursor simulation and thus within a single computational domain. The roughness of the terrain surface is modeled by implementing a new wall function into OpenFOAM® during the thesis work. Both, the recycling method and the newly implemented wall function, are validated for the channel flows at relatively high Reynolds number before applying them to the atmospheric flow applications. After validating the LES model over simple flows, the simulations are carried out for atmospheric boundary-layer flows over two types of hills: first, two-dimensional wind-tunnel hill profiles and second, the Bolund hill located in Roskilde Fjord, Denmark. For the twodimensional wind-tunnel hills, the study focuses on the overall flow behavior as a function of the hill slope. Moreover, the simulations are repeated using another wall function suitable for smooth surfaces, which already existed in OpenFOAM® , in order to study the sensitivity of the flow to the surface roughness in ABL flows. The simulated results obtained using the two wall functions are compared against the wind-tunnel measurements. It is shown that LES using the implemented wall function produces overall satisfactory results on the turbulent flow over the two-dimensional hills. The prediction of the flow separation and reattachment-length for the steeper hill is closer to the measurements than the other numerical studies reported in the past for the same hill geometry. The field measurement campaign performed over the Bolund hill provides the most recent field-experiment dataset for the mean flow and the turbulence properties. A number of research groups have simulated the wind flows over the Bolund hill. Due to the challenging features of the hill such as the almost vertical hill slope, it is considered as an ideal experimental test case for validating micro-scale CFD models for wind energy applications. In this work, the simulated results obtained for two wind directions are compared against the field measurements. It is shown that the present LES can reproduce the complex turbulent wind flow structures over a complicated terrain such as the Bolund hill. Especially, the present LES results show the best prediction of the turbulent kinetic energy with an average error of 24.1%, which is a 43% smaller than any other model results reported in the past for the Bolund case. Finally, the validated LES methodology is demonstrated to simulate the wind flow over the existing Muukko wind farm located in South-Eastern Finland. The simulation is carried out only for one wind direction and the results on the instantaneous and time-averaged wind speeds are briefly reported. The demonstration case is followed by discussions on the practical aspects of LES for the wind resource assessment over a realistic inland wind farm.

Spec. karta Evropejskoj Rossìi. 25 (11/40) / izd. Voen. top. upravl. General'n. Štaba ; pod" redakc. Strěl'bickago.

Masštab" v" Anglìjskom" dûjmě 10 russk. verst" ili 1:420000.

Large scale solar power plant flat roof and carport installation in Finland

This work focuses on the 159.5 kW solar photovoltaic power plant project installed at the Lappeenranta University of Technology in 2013 as an example of what a solar plant project could be in Finland. The project consists of a two row carport and a flat roof installation on the roof of the university laboratories. The purpose of this project is not only its obvious energy savings potential but also to serve as research and teaching laboratory tool. By 2013, there were not many large scale solar power plants in Finland. For this reason, the installation and data experience from the solar power plant at LUT has brought valuable information for similar projects in northern countries. This work includes a first part for the design and acquisition of the project to continue explaining about the components and their installation. At the end, energy produced by this solar power plant is studied and calculated to find out some relevant economical results. For this, the radiation arriving to southern Finland, the losses of the system in cold weather and the impact of snow among other aspects are taken into account.

Simulation model of wind turbine gearbox and lubrication system

As increasing efficiency of a wind turbine gearbox, more power can be transferred from rotor blades to generator and less power is used to cause wear and heating in the gearbox. By using a simulation model, behavior of the gearbox can be studied before creating expensive prototypes. The objective of the thesis is to model a wind turbine gearbox and its lubrication system to study power losses and heat transfer inside the gearbox and to study the simulation methods of the used software. Software used to create the simulation model is Siemens LMS Imagine.Lab AMESim, which can be used to create one-dimensional mechatronic system simulation models from different fields of engineering. When combining components from different libraries it is possible to create a simulation model, which includes mechanical, thermal and hydraulic models of the gearbox. Results for mechanical, thermal, and hydraulic simulations are presented in the thesis. Due to the large scale of the wind turbine gearbox and the amount of power transmitted, power loss calculations from AMESim software are inaccurate and power losses are modelled as constant efficiency for each gear mesh. Starting values for simulation in thermal and hydraulic simulations were chosen from test measurements and from empirical study as compact and complex design of gearbox prevents accurate test measurements. In further studies to increase the accuracy of the simulation model, components used for power loss calculations needs to be modified and values for unknown variables are needed to be solved through accurate test measurements.

Impacts of increased levels of wind penetration on the Electric Power System of the Åland Islands

The application of VSC-HVDC technology throughout the world has turned out to be an efficient solution regarding a large share of wind power in different power systems. This technology enhances the overall reliability of the grid by utilization of the active and reactive power control schemes which allows to maintain frequency and voltage on busbars of the end-consumers at the required level stated by the network operator. This master’s thesis is focused on the existing and planned wind farms as well as electric power system of the Åland Islands. The goal is to analyze the wind conditions of the islands and appropriately predict a possible production of the existing and planned wind farms with a help of WAsP software program. Further, to investigate the influence of increased wind power it is necessary to develop a simulation model of the electric grid and VSC-HVDC system in PSCAD and examine grid response to different wind power production cases with respect to the grid code requirements and ensure the stability of the power system.

Tulospalkkausjärjestelmän kehittäminen startup-yrityksen näkökulmasta Case: Idea Roof

Työssä tutkitaan tulospalkkausjärjestelmän kehittämistä kohdeyritykselle.