Virtual Testing of Active Magnetic Bearing Systems based on Design Guidelines given by the Standards

Active Magnetic Bearings offer many advantages that have brought new applications to the industry. However, similarly to all new technology, active magnetic bearings also have downsides and one of those is the low standardization level. This thesis is studying mainly the ISO 14839 standard and more specifically the system verification methods. These verifying methods are conducted using a practical test with an existing active magnetic bearing system. The system is simulated with Matlab using rotor-bearing dynamics toolbox, but this study does not include the exact simulation code or a direct algebra calculation. However, this study provides the proof that standardized simulation methods can be applied in practical problems.

Active Magnetic Bearing System Identification Methods and Rotor Model Updating

Active magnetic bearing is a type of bearing which uses magnetic field to levitate the rotor. These bearings require continuous control of the currents in electromagnets and data from position of the rotor and the measured current from electromagnets. Because of this different identification methods can be implemented with no additional hardware. In this thesis the focus was to implement and test identification methods for active magnetic bearing system and to update the rotor model. Magnetic center calibration is a method used to locate the magnetic center of the rotor. Rotor model identification is an identification method used to identify the rotor model. Rotor model update is a method used to update the rotor model based on identification data. These methods were implemented and tested with a real machine where rotor was levitated with active magnetic bearings and the functionality of the methods was ensured. Methods were developed with further extension in mind and also with the possibility to apply them for different machines with ease.

Political Legitimacy and Ethnocultural Justice. Essays on Public Reason, Democratic Citizenship, and the Rights of Cultural Minorities

In this thesis, I argue that there are public cultural reasons that can underpin public justifications of minority rights of indigenous and national minorities in a constitutionaldemocracy. I do so by tackling diverse issues facing a liberal theory of multiculturalism. In the first essay, I criticize Will Kymlicka’s comprehensive liberal theory of minority rights and propose a political liberal alternative. The main problem of Will Kymlicka’s theory is that it builds on the contestable liberal value of individual autonomy and thus fails to take diversity seriously. In the second essay, I elaborate on the Rawlsian political liberalism assumed here by criticizing Chandran Kukathas’s version of political liberalism as overly accommodating to diversity. In the third essay, I discuss questions of method that arise for a political liberal approach to the moral-political foundations of multiculturalism, and propose a certain understanding of the political liberal enterprise and its crucial standard of reasonableness. In the fourth essay, I dwell on the political liberal ethic of citizenship and propose a strongly inclusionist interpretation of the duty of civility. In the fifth and last essay, I introduce a certain understanding of ethnocultural justice and propose a view on certain cultural reasons as public cultural reasons. Cultural reasons are public when they are based on necessarily established cultural marks of a democratic polity, as specified by the cultural establishment view; and when they are crucial for the societal cultural bases of self-respect of citizens. The arguments in this thesis support, and help to spell out, moral-political rights of indigenous and national minorities as formulated in international legal documents, such as the Declaration on the Rights of Indigenous Peoples (United Nations 2007) or the International Covenant on Economic, Social and Cultural Rights (United Nations 1966).

Relay protection in active distribution networks

Increasingly growing share of distributed generation in the whole electrical power system’s generating system is currently a worldwide tendency, driven by several factors, encircling mainly difficulties in refinement of megalopolises’ distribution networks and its maintenance; widening environmental concerns adding to both energy efficiency approaches and installation of renewable sources based generation, inherently distributed; increased power quality and reliability needs; progress in IT field, making implementable harmonization of needs and interests of different-energy-type generators and consumers. At this stage, the volume, formed by system-interconnected distributed generation facilities, have reached the level of causing broad impact toward system operation under emergency and post-emergency conditions in several EU countries, thus previously implementable approach of their preliminary tripping in case of a fault, preventing generating equipment damage and disoperation of relay protection and automation, is not applicable any more. Adding to the preceding, withstand capability and transient electromechanical stability of generating technologies, interconnecting in proximity of load nodes, enhanced significantly since the moment Low Voltage Ride-Through regulations, followed by techniques, were introduced in Grid Codes. Both aspects leads to relay protection and auto-reclosing operation in presence of distributed generation generally connected after grid planning and construction phases. This paper proposes solutions to the emerging need to ensure correct operation of the equipment in question with least possible grid refinements, distinctively for every type of distributed generation technology achieved its technical maturity to date and network’s protection. New generating technologies are equivalented from the perspective of representation in calculation of initial steady-state short-circuit current used to dimension current-sensing relay protection, and widely adopted short-circuit calculation practices, as IEC 60909 and VDE 0102. The phenomenon of unintentional islanding, influencing auto-reclosing, is addressed, and protection schemes used to eliminate an sustained island are listed and characterized by reliability and implementation related factors, whereas also forming a crucial aspect of realization of the proposed protection operation relieving measures.