Direct-on-line axial flux permanent magnet synchronous generator static and dynamic performance

In distributed energy production, permanent magnet synchronous generators (PMSG) are often connected to the grid via frequency converters, such as voltage source line converters. The price of the converter may constitute a large part of the costs of a generating set. Some of the permanent magnet synchronous generators with converters and traditional separately excited synchronous generators couldbe replaced by direct-on-line (DOL) non-controlled PMSGs. Small directly networkconnected generators are likely to have large markets in the area of distributed electric energy generation. Typical prime movers could be windmills, watermills and internal combustion engines. DOL PMSGs could also be applied in island networks, such as ships and oil platforms. Also various back-up power generating systems could be carried out with DOL PMSGs. The benefits would be a lower priceof the generating set and the robustness and easy use of the system. The performance of DOL PMSGs is analyzed. The electricity distribution companies have regulations that constrain the design of the generators being connected to the grid. The general guidelines and recommendations are applied in the analysis. By analyzing the results produced by the simulation model for the permanent magnet machine, the guidelines for efficient damper winding parameters for DOL PMSGs are presented. The simulation model is used to simulate grid connections and load transients. The damper winding parameters are calculated by the finite element method (FEM) and determined from experimental measurements. Three-dimensional finite element analysis (3D FEA) is carried out. The results from the simulation model and 3D FEA are compared with practical measurements from two prototype axial flux permanent magnet generators provided with damper windings. The dimensioning of the damper winding parameters is case specific. The damper winding should be dimensioned based on the moment of inertia of the generating set. It is shown that the damper winding has optimal values to reach synchronous operation in the shortest period of time after transient operation. With optimal dimensioning, interferenceon the grid is minimized.

Development of management accounting practices in energy operations in a forest industry Company

The aim of this master’s thesis was to map the management accounting processes and reporting of an internal service unit. The research was conducted in energy services in a forest industry company. Research questions and the results of the study are highly specific for the case unit although some generalizable features of management accounting in internal service units under shared services were searched. The research was carried out as a qualitative action research and a single case study. Internal benchmarking was used to find best practices from other units and to get a comprehensive understanding of the financial processes of the case company. Empirical data for the study was collected with participant observation, interviews of experts and by exploring internal company documents. A literature review was conducted to outline the subject and to support the study. Although the management accounting processes of the case unit were found to be on a good level, some improvement ideas were presented. Results of the research show that the needs of the customers are in the key role in the processes of an internal service unit. Management accounting and reporting need to support the company strategy and management decision-making. To evaluate the performance of the service unit both financial and non-financial measures are needed.