Utilization of a Time Domain Simulator in the Technical and Economic Analysis of a Wind Turbine Electric Drive Train

The amount of installed wind power has been growing exponentially during the past ten years. As wind turbines have become a significant source of electrical energy, the interactions between the turbines and the electric power network need to be studied more thoroughly than before. Especially, the behavior of the turbines in fault situations is of prime importance; simply disconnecting all wind turbines from the network during a voltage drop is no longer acceptable, since this would contribute to a total network collapse. These requirements have been a contributor to the increased role of simulations in the study and design of the electric drive train of a wind turbine. When planning a wind power investment, the selection of the site and the turbine are crucial for the economic feasibility of the installation. Economic feasibility, on the other hand, is the factor that determines whether or not investment in wind power will continue, contributing to green electricity production and reduction of emissions. In the selection of the installation site and the turbine (siting and site matching), the properties of the electric drive train of the planned turbine have so far been generally not been taken into account. Additionally, although the loss minimization of some of the individual components of the drive train has been studied, the drive train as a whole has received less attention. Furthermore, as a wind turbine will typically operate at a power level lower than the nominal most of the time, efficiency analysis in the nominal operating point is not sufficient. This doctoral dissertation attempts to combine the two aforementioned areas of interest by studying the applicability of time domain simulations in the analysis of the economicfeasibility of a wind turbine. The utilization of a general-purpose time domain simulator, otherwise applied to the study of network interactions and control systems, in the economic analysis of the wind energy conversion system is studied. The main benefits of the simulation-based method over traditional methods based on analytic calculation of losses include the ability to reuse and recombine existing models, the ability to analyze interactions between the components and subsystems in the electric drive train (something which is impossible when considering different subsystems as independent blocks, as is commonly done in theanalytical calculation of efficiencies), the ability to analyze in a rather straightforward manner the effect of selections other than physical components, for example control algorithms, and the ability to verify assumptions of the effects of a particular design change on the efficiency of the whole system. Based on the work, it can be concluded that differences between two configurations can be seen in the economic performance with only minor modifications to the simulation models used in the network interaction and control method study. This eliminates the need ofdeveloping analytic expressions for losses and enables the study of the system as a whole instead of modeling it as series connection of independent blocks with no lossinterdependencies. Three example cases (site matching, component selection, control principle selection) are provided to illustrate the usage of the approach and analyze its performance.

Induction Motor Drive Energy Efficiency - Simulation and Analysis

A coupled system simulator, based on analytical circuit equations and a finite element method (FEM) model of the motor has been developed and it is used to analyse a frequency-converterfed industrial squirrel-cage induction motor. Two control systems that emulate the behaviour of commercial direct-torque-controlled (DTC) and vector-controlled industrial frequency converters have been studied, implemented in the simulation software and verified by extensive laboratory tests. Numerous factors that affect the operation of a variable speed drive (VSD) and its energy efficiency have been investigated, and their significance in the simulation of the VSD results has been studied. The dependency of the frequency converter, induction motor and system losses on the switching frequency is investigated by simulations and measurements at different speeds for both the vector control and the DTC. Intensive laboratory measurements have been carried out to verify the simulation results.

Doubly fed induction generator versus direct drive permanent magnet synchronous generator in wind power applications

The objective of this master's thesis is to compare two different generator systems for wind turbines. It is the doubly fed induction generator system with three stage gearbox and the direct drive permanent magnet generator system. The comparison of generator systems is based on annual energy production for a given wind climate. For comparison a 3 MW, 15 rpm wind turbine is used. Modelling of a turbine rotor, gearbox and converters were done. Design of two generators was done and their performance was examined.

Centralized Motion Control of a Linear Tooth Belt Drive: Analysis of the Performance and Limitations

A centralized robust position control for an electrical driven tooth belt drive is designed in this doctoral thesis. Both a cascaded control structure and a PID based position controller are discussed. The performance and the limitations of the system are analyzed and design principles for the mechanical structure and the control design are given. These design principles are also suitable for most of the motion control applications, where mechanical resonance frequencies and control loop delays are present. One of the major challenges in the design of a controller for machinery applications is that the values of the parameters in the system model (parameter uncertainty) or the system model it self (non-parametric uncertainty) are seldom known accurately in advance. In this thesis a systematic analysis of the parameter uncertainty of the linear tooth beltdrive model is presented and the effect of the variation of a single parameter on the performance of the total system is shown. The total variation of the model parameters is taken into account in the control design phase using a Quantitative Feedback Theory (QFT). The thesis also introduces a new method to analyze reference feedforward controllers applying the QFT. The performance of the designed controllers is verified by experimentalmeasurements. The measurements confirm the control design principles that are given in this thesis.

Intercultural bridges in teenagers' theatrical events : performing self and constructing cultural identity through a creative drama process

The overriding aim of this drama educational case study is to deepen the understanding of meaning making in a creative intercultural youth theatre process and to examine it in the context of the 10th European Children's TheatreEncounter. The research task is to give a theoretical description of some key features of a creative drama process as the basis for theory about meaning makingin physical theatre. The first task is to illuminate the culture-historical connections of the multilayered practice of the EDERED-association. The second taskis to analyse and interpret theatrical meaning making. The ethnographical research site is regarded as a theatrical event. The analysis of the theatrical eventis divided into four segments: cultural contexts, contextual theatricality, theatrical playing and playing culture. These segments are connected with four research questions: What are the cultural contexts of a creative drama process? How can the organisation of the Encounter, genres, aesthetic codes and perception ofcodes be seen to influence the lived experiences of the participants? What are some of the key phases and characteristics in a creative practice? What kind of cultural learning can be interpreted from the performance texts? The interpretative question concerns identity and community (re)construction. How are the categories, `community´ and `child´ constructed in the Encounter culture? In this drama educational case study the research material (transcribed interviews, coded questionnaire answers, participant drawings, videotaped process text and performance texts) are examined in a multi-method analysis in the meta-theoretical framework of Dewey's naturalistic pragmatism. A three-dimensional research interest through a combination of lived experiences, social contexts and cultural-aesthetical practices compared with drama-educational practices required the methodological project of cultural studies. Furthermore, the critical interpretation of cultural texts is divided into three levels of analyses which are called description, structural analysis and theoretical interpretation. Dialogic validity (truthfulness, self-reflexivity and polyvocality) is combined with contextual validity (sensitivity to social context and awareness of historicity) and with deconstructive validity (awareness of the social discourses). My research suggests that itis possible, by means of physical theatre, to construct symbolic worlds where questions about intercultural identity and multilingual community are examined and where provisional answers are constructed in social interaction.

Electric-drive-based control and electric energy regeneration in a hydraulic system

Over the recent years, development in mobile working machines has concentrated on reducing emissions owing to the tightening rules and needs to improve energy utilization and reduce power losses. This study focuses on energy utilization and regeneration in an electro-hydraulic forklift, which is a lifting equipment application. The study starts from the modelling and simulation of a hydraulic forklift. The energy regeneration from the potential energy of the load was studied. Also a flow-based electric motor speed control was suggested in this thesis instead of the throttle control method or the variable displacement pump control. Topics related to further development in the future are discussed. Finally, a summary and conclusions are presented.

Recording and reproducing Soundscapes : using and interpreting data in a creative way

http://elo.aalto.fi/fi/studies/elomedia/dataseminar/

Energy storage in electric drive system

In recent years the environmental issues and the energy saving have become increasingly import in modern society where industry is the major emission factor and energy consumer. Generally, most of the total energy consumption is caused by electrical drives used in industrial applications and thus improving the performance of electrical drives give an opportunity to improve the energy efficiency. In this Master Thesis improving the energy efficiency in different electrical drives is clarified with different cases: regenerative braking in the electric grid or recovery of the braking energy into an energy storage. In addition, as an example, the energy consumption of an elevator is analyzed by measurements. From these measurement results it can be estimated how much the share of the standby energy consumption is from the total energy consumption and how much regenerative energy is available. The latter part of the thesis concentrates on determination of the properties of lithium iron phosphate battery with measurements.

Servo drive in hoist application

The objective of this master thesis is to test according to hoisting requirements, a servo drive system and compare its performance with the performance of a drive equipped with a vector controlled frequency converter. Both systems utilize closed-loop vector control based on PCL program control. In order to compare the results of tests both systems were connected to the same motor driving a variable speed electrical chain hoist. Tests were based on requirements to both systems. As requirements of tests zero speed operation, operation in field weakening, positioning accuracy and smoothness of motion are taken into consideration. Both systems demonstrate quite similar performance and meet the requirements. Servo drive system demonstrates a high positioning accuracy and dynamic performance. Frequency converter is not able to provide the same positioning accuracy and dynamic performance as servo drive.

Building a creative city brand through an international mega-event : Case: Helsinki World Design Capital 2012

In order to grow, cities are increasingly competing for attention, jobs, investments, visitors, residents and significant events. Cities need to come up with creative solutions to keep up with the competition; they ought to become creative cities. Attracting talented and diverse inhabitants is a key factor in developing a creative city, which on is characterized by openness, tolerance, vibrancy and diversity. Along the need for renewed city images city brand building has become popular. Helsinki is the World Design Capital 2012 (WDC 2012) and this mega-event presents a meaningful opportunity for the city to broadcast itself globally. The purpose of this study is to evaluate how Helsinki brands itself as a creative city through an international mega-event. The sub-aims are to: 1) Map the factors behind the creative city and their relation to the city of Helsinki, 2) Describe the city branding process, 3) Evaluate the role of the Helsinki World Design Capital 2012 mega-event in Helsinki’s creative city brand building. First, the theory discusses the concept of the creative city that has gained growing attention during the past decade. Then, the city branding process is described and the benefits of hosting a mega-event are presented. Finally, co-branding a city and a mega-event in order to generate maximum benefit from the mega-event, is reviewed. This is a qualitative research for which data was collected through three face-to-face interviews, the World Design Capital 2012 bid, Helsinki’s economic development strategy, a consulting firm’s research report on the case city and web-pages. The research reveals that Helsinki has shown interest in the creative city discussion. The terminology around the concept is however approached carefully. Helsinki fits many of the creative city characteristics and recognizes its flaws for which improvement strategies have been planned. Bottlenecks keeping the city from promoting a more open mind were mainly revealed in its organizational structures. Helsinki has no official brand strategy; nonetheless pressure to develop one is present. The World Design Capital 2012 mega-event is seen as a meaningful stepping board to strengthen Helsinki’s identity and image, and start thinking about a city brand. The brand strategies of the mega-event support the values and virtues of the city itself, which enables benefits of co-branding introduces in the theory part. Helsinki has no official brand and doesn’t call itself a creative city, however this study shows signs of the city taking steps towards building a creative city brand with the help of the Helsinki World Design Capital 2012 mega-event.

Improving the inventory management and valuation process, Case: The Switch Drive Systems

The goal of this study is to create a new inventory valuation process for The Switch Drive Systems and to improve its inventory management practices. In the matter of inventories the main problems in the case company are that it doesn’t have consistent valuation methods throughout the company and that information received in ERP system isn’t trustful. The research is qualitative case study. The empirical data is gathered through observing and unstructured interviews. The research shows that material flow process and the inventory valuation must be divided and handled separately but they should interact with each other. The result is a new inventory valuation process which takes many factors of material process under the consideration in order to receive reliable value for inventories.

Creative brand launch in phamaceutical over-the-counter markets – case Burana

The purpose of this study is to examine how a launch of a pharmaceutical over-the-counter sold (OTC) brand can be done by using creative solutions and thus affecting the product life cycle. The study is inspired by a phenomenon called Burana. The Burana brand has been a market leader of OTC painkillers in Finland for the past 27 years. The aim of this study is to “solve the mystery” behind Burana brand’s success by focusing on the launch phase of Burana as an OTC medicine. Farmos Group Ltd (the owner of the brand in 1980´s) had not originally invented the product in question – ibuprofen – and the product had already reached it´s maturity phase, if not even decline from the product life cycle aspect when this phenomenon takes place. This has made the marketing choices, the product launch phase as well as the product management even more interesting from the company point of view as well as from a learning point of view. The methodology in this study is qualitative with a descriptive research strategy, while the study is conducted as a longitudinal single-case study. The methods used in this study have been collecting, analyzing and interpreting the data, which is based on the interviewees’ comments and observed behavior. According to the study, the successful launch phase helped in setting the product one step ahead of the competitors and thus aided the brand leadership and prolonged the product life cycle. Another notable aspect that became clear from the interviews and the documentary of Burana´s launch phase was the innovative idea of involving the people of the distribution chain into the product launch through education. As this study has pointed out, it is not enough to for a company to build an innovative team of employees, but also to offer them an involved and encouraging management. According to the interviews, the support from the company management gave the marketing team the encouragement to be innovative. It can be thus stated that the management of a company has an essential role in fostering the creativity within the company.

Variable speed drive in fan system monitoring

Fan systems are responsible for approximately 10% of the electricity consumption in industrial and municipal sectors, and it has been found that there is energy-saving potential in these systems. To this end, variable speed drives (VSDs) are used to enhance the efficiency of fan systems. Usually, fan system operation is optimized based on measurements of the system, but there are seldom readily installed meters in the system that can be used for the purpose. Thus, sensorless methods are needed for the optimization of fan system operation. In this thesis, methods for the fan operating point estimation with a variable speed drive are studied and discussed. These methods can be used for the energy efficient control of the fan system without additional measurements. The operation of these methods is validated by laboratory measurements and data from an industrial fan system. In addition to their energy consumption, condition monitoring of fan systems is a key issue as fans are an integral part of various production processes. Fan system condition monitoring is usually carried out with vibration measurements, which again increase the system complexity. However, variable speed drives can already be used for pumping system condition monitoring. Therefore, it would add to the usability of a variablespeed- driven fan system if the variable speed drive could be used as a condition monitoring device. In this thesis, sensorless detection methods for three lifetime-reducing phenomena are suggested: these are detection of the fan contamination build-up, the correct rotational direction, and the fan surge. The methods use the variable speed drive monitoring and control options for the detection along with simple signal processing methods, such as power spectrum density estimates. The methods have been validated by laboratory measurements. The key finding of this doctoral thesis is that a variable speed drive can be used on its own as a monitoring and control device for the fan system energy efficiency, and it can also be used in the detection of certain lifetime-reducing phenomena.

Wind Turbine Direct-Drive Permanent-Magnet Generator with Direct Liquid Cooling for Mass Reduction

Today’s electrical machine technology allows increasing the wind turbine output power by an order of magnitude from the technology that existed only ten years ago. However, it is sometimes argued that high-power direct-drive wind turbine generators will prove to be of limited practical importance because of their relatively large size and weight. The limited space for the generator in a wind turbine application together with the growing use of wind energy pose a challenge for the design engineers who are trying to increase torque without making the generator larger. When it comes to high torque density, the limiting factor in every electrical machine is heat, and if the electrical machine parts exceed their maximum allowable continuous operating temperature, even for a short time, they can suffer permanent damage. Therefore, highly efficient thermal design or cooling methods is needed. One of the promising solutions to enhance heat transfer performances of high-power, low-speed electrical machines is the direct cooling of the windings. This doctoral dissertation proposes a rotor-surface-magnet synchronous generator with a fractional slot nonoverlapping stator winding made of hollow conductors, through which liquid coolant can be passed directly during the application of current in order to increase the convective heat transfer capabilities and reduce the generator mass. This doctoral dissertation focuses on the electromagnetic design of a liquid-cooled direct-drive permanent-magnet synchronous generator (LC DD-PMSG) for a directdrive wind turbine application. The analytical calculation of the magnetic field distribution is carried out with the ambition of fast and accurate predicting of the main dimensions of the machine and especially the thickness of the permanent magnets; the generator electromagnetic parameters as well as the design optimization. The focus is on the generator design with a fractional slot non-overlapping winding placed into open stator slots. This is an a priori selection to guarantee easy manufacturing of the LC winding. A thermal analysis of the LC DD-PMSG based on a lumped parameter thermal model takes place with the ambition of evaluating the generator thermal performance. The thermal model was adapted to take into account the uneven copper loss distribution resulting from the skin effect as well as the effect of temperature on the copper winding resistance and the thermophysical properties of the coolant. The developed lumpedparameter thermal model and the analytical calculation of the magnetic field distribution can both be integrated with the presented algorithm to optimize an LC DD-PMSG design. Based on an instrumented small prototype with liquid-cooled tooth-coils, the following targets have been achieved: experimental determination of the performance of the direct liquid cooling of the stator winding and validating the temperatures predicted by an analytical thermal model; proving the feasibility of manufacturing the liquid-cooled tooth-coil winding; moreover, demonstration of the objectives of the project to potential customers.

Adaptive control of Hydraulic Drive

Adaptive control systems are one of the most significant research directions of modern control theory. It is well known that every mechanical appliance’s behavior noticeably depends on environmental changes, functioning-mode parameter changes and changes in technical characteristics of internal functional devices. An adaptive controller involved in control process allows reducing an influence of such changes. In spite of this such type of control methods is applied seldom due to specifics of a controller designing. The work presented in this paper shows the design process of the adaptive controller built by Lyapunov’s function method for the Hydraulic Drive. The calculation needed and the modeling were conducting with MATLAB® software including Simulink® and Symbolic Math Toolbox™ etc. In the work there was applied the Jacobi matrix linearization of the object’s mathematical model and derivation of the suitable reference models based on Newton’s characteristic polynomial. The intelligent adaptive to nonlinearities algorithm for solving Lyapunov’s equation was developed. Developed algorithm works properly but considered plant is not met requirement of functioning with. The results showed confirmation that adaptive systems application significantly increases possibilities in use devices and might be used for correction a system’s behavior dynamics.