För majoriteten av Umeå universitetscampus finns en anslutningspunkt för fjärrvärme från Umeå Energi. Under januari 2024 uppstod problem när fjärrvärmeeffekten överskred den abonnerade nivån under några extremt kalla dagar, vilket resulterade i straffavgifter från leverantören. Projektets syfte är att analysera och lösa överbelastningsproblemen genom att hitta och jämföra olika förbättringar för värmesystemen på campus. Effektsignaturer analyserades för utvärdering av variationen i den inköpta fjärrvärmen på Umeå universitetscampus, för drift under och utanför verksamhetstid. Resultaten visar en maximal potentiell effektreduktion på 29,4% vid DVUT (dimensionerande vinterutetemperatur). En strategisk driftstrategi kan tillämpas genom att ändra styrsystemets globala tidsschema till röd dag för att uppnå effektreduktion i byggnader utan närvaro. Detta motsvarar en maximal potentiell ekonomisk besparing på 1,7 miljoner kronor för den totala effektreduktionen. Effektkartläggning av Fysikhusets värmesystem utfördes. Resultatet vid DVUT visade att radiatorerna endast stod för 30% av fjärrvärmeeffekten, LA001 (ventilationsaggregat i Fysikhuset, laborationssalar) 64% och LA002 (ventilationsaggregat i Fysikhuset, kontor) 6%. Fysikhusets variation i fjärrvärmebehov under och utanför verksamhetstid vid DVUT visar en minimal skillnad på endast 0,3%, vilket främst beror på värmesystemens utformning och verksamheten som bedrivs. Radiatorernas effektbehov i Fysikhuset vid DVUT analyserades vid sänkning av inomhustemperatur från 21°C till 18°C. Resultaten visar en effektreduktion på 8,7kW och en ekonomisk besparing på 5 746kr, jämfört med radiatorernas normala effektbehov på 43,5kW. Sänkning av ventilationsflöde i Fysikhuset enligt BBR (Boverkets byggregler) visar potential för betydande effektreduktion, med möjlighet att minska ventilationen upp till 61,8% under närvaro och 89,1% utanför närvaro, vilket kan leda till en ekonomisk besparing på mellan 4 700 - 59 500kr. Beräkningar visar att för varje grad (°C) sänkning av tilluftstemperaturen i Fysikhusets ventilation kan en effektreduktion på LA001 och LA002 uppnå 4kW och 3,7kW per grad respektive, vid DVUT. / For most of the buildings on Umeå University campus there is one main connection point for district heating from Umeå Energi. In January 2024 problems occurred when the district heating output exceeded the subscribed level during some extremely cold days, resulting in penalty charges from the supplier. The purpose of the project is to analyse and solve the overload problems by finding and comparing different improvements for the heating systems on campus. Power signatures were analysed for evaluation of the variation in the purchased district heating at Umeå University campus, for operation during and outside business hours. The results show a maximum potential power reduction of 29,4% at DVUT (dimensioned winter outdoor temperature). An operating strategy can be applied by changing the control system's global time schedule to public holiday to achieve a power reduction in unoccupied buildings. This corresponds to a maximum potential financial saving of SEK 1,7 million for the total effect reduction. Power mapping of the building “Fysikhusets” heating system was carried out. The results at DVUT showed that the radiators accounted for only 30% of the district heating power, LA001 (ventilation unit in Fysikhuset, laboratory rooms) 64% and LA002 (ventilation unit in Fysikhuset, offices) 6%. The district heating demand variation in Fysikhuset during and outside of operating hours at DVUT shows a minimal difference of only 0,3%, which is mainly due to the design of the heating systems and the operations that are carried out in the building. A power reduction on the radiators in Fysikhuset was analysed by lowering the indoor temperatures from 21°C to 18°C, the results showed a power reduction of 8,7 kW and a financial saving of SEK 5 746. Compared to the radiators normal power requirement of 43,5kW. Reduction of ventilation flow in Fysikhuset according to BBR (Boverket´s building regulations) shows potential for significant power reduction, with the possibility of reducing ventilation up to 61,8% during attendance and 89,1% without attendance, which can lead to a financial saving of between SEK 4,700 - 59,500. Calculations show that for each degree (°C) lowering of the supply air temperature in Fysikhusets ventilation, a power reduction on LA001 and LA002 can reach 4kW and 3,7kW for each degree respectively, at DVUT.

A stall-regulated wind turbine with fixed-speed operation provides a configuration which is one of the cheapest and simplest forms of wind generation and configurations. This type of turbine, however, is non-optimal at low winds, stresses the component structure and gives rise to significant power peaks during early stall conditions at high wind speeds. These problems can be overcome by having a properly designed generator speed control. Therefore, to track the maximum power locus curve at low winds, suppress the power peaks at medium winds, limit the power at a rated level at high winds and obtain a satisfactory power-wind speed curve performance (that closely resembles the ideal power-wind speed curve) with minimum stress torque simultaneously over the whole range of the wind speed variations, the availability of active control is vital. The main purpose of this study is to develop an internal model control (IMC) design for the squirrel-cage induction generator (SCIG), coupled with a full-rated power converter of a small (25 kW), stall-regulated, variable-speed wind-turbine (SRVSWT) system, which is subject to variations in the generator speed, electromagnetic torque and rotor flux. The study was done using simulations only. The objective of the controller was to optimise the generator speed to maximise the active power generated during the partial load region and maintain or restrict the generator speed to reduce/control the torque stress and the power-peaking between the partial and full load regions, before power was limited at the rated value of 25 kW at the full load region. The considered investigation involved estimating the proportional-integral (PI) and integral-proportional (IP) controllers parameter values used to track the stator-current producing torque, the rotor flux and the angular mechanical generator speed, before being used in the indirect vector control (IVC) and the sensorless indirect vector control (SLIVC) model algorithms of the SCIG system. The design of the PI and IP controllers was based on the fourth-order model of the SCIG, which is directly coupled to the full-rated power converter through the machine stator, whereas the machine rotor is connected to the turbine rotor via a gearbox. Both step and realistic wind speed profiles were considered. The IMC-based PI and IP controllers (IMC-PI-IP) tuning rule was proven to have smoothened the power curve and shown to give better estimation results compared to the IMC-based PI controllers (IMC-PI), Ziegler-Nichols (ZN) and Tyreus-Luyben (ZN) tuning rules. The findings also showed that for the SRVSWT system that employed the IVC model algorithm with the IMC-PI-IP tuning rule, considering the application of a maintained/constant speed (CS) strategy at the intermediate load region is more profitable than utilizing SRVSWT with the modified power tracking (MoPT) strategy. Besides that, the finding also suggested that, for the IMC-PI-IP approach, the IVC does provide better power tracking performance than the SLIVC model algorithm.

Made available in DSpace on 2016-03-15T19:33:37Z (GMT). No. of bitstreams: 1 Bruno Boris Carlos Croce.pdf: 941598 bytes, checksum: 320c85cc3bab323afe22ee5268b27e61 (MD5) Previous issue date: 2010-07-27 / The question of the interpretation of contractual clauses of consumption contracts is a problem faced for the applicator of Law. Specifically on the analysis of an abusive contractual clause it is important to the interpreter to appreciate all available the elements, especially the influence of the economic power in consumer issues. Besides the interpreter are not able to ignore the instrumental capacity of the general clause of good-faith, the absence of the analysis by the judge about the influence of the economic power in contracts harms a effective jurisdictional rendering to real case. The limitation by the applicator of Law to the individual questions and not much relevance given to the economic power as relevant force in the contractual drafting cause deficiency on the interpretation and harm an efficient control of the abusive clauses. / A questão da interpretação das cláusulas contratuais nos contratos de consumo é um problema enfrentado pelos aplicadores do direito. Especificamente na análise e na constatação de uma cláusula contratual abusiva é relevante que o intérprete aprecie todos os elementos que estejam à sua disposição, porém, especialmente perceber desta análise o quanto há de influência do poder econômico nas relações de consumo. Além do fato de o intérprete não poder ignorar a capacidade instrumental da cláusula geral de boa-fé no momento do estudo do instrumento contratual, a ausência da análise por parte do julgador sobre a influência do poder econômico nos contratos prejudica uma prestação jurisdicional efetiva ao caso concreto. A limitação por parte do aplicador da lei às questões individuais e a pouca importância dada ao poder econômico como relevante força na elaboração contratual, ocasionam uma interpretação deficiente e prejudicam o controle eficaz das cláusulas abusivas.