http://lutpub.lut.fi:80/handle/10024/158298 2026-08-11T04:41:09Z 2026-08-11T04:41:09Z Matilainen, Tomi http://lutpub.lut.fi:80/handle/10024/172713 2026-08-10T10:30:15Z 2026-01-01T00:00:00Z

Utilizing a novel technology arc suppression coil in MV distribution network Matilainen, Tomi This master's thesis investigates the applicability of a novel arc suppression coil (ASC) technology in a U.S. medium-voltage (MV) distribution network. Single-line-to-earth faults are the most common fault type in MV networks, making their effective compensation an important aspect of distribution system reliability. The objective of this study was to evaluate the performance of a novel ASC and compare it with conventional grounding methods. The research was carried out using a simulation-based approach in a representative MV distribution network, modelled in MATLAB/Simulink. The simulation results showed that resonance grounding significantly reduced the residual earth fault current compared with the solidly grounded network. The novel ASC achieved compensation comparable to a conventional coil while accurately regulating its inductance throughout the investigated operating conditions. The results also indicated that the practical optimum compensation point may differ from the theoretical tuning point because of network asymmetry, highlighting the importance of modern tuning methods. Although the developed model successfully reproduced the investigated earth-fault current characteristics, unexpected phase-to-ground voltage behaviour, identified during the simulations, indicates that further refinement of the network model is required for complete voltage validation. Based on the obtained results, the novel ASC technology appears well suited for MV distribution networks in which network capacitance and operating conditions vary over time. The findings support the applicability of novel ASC for reducing manual tuning and enabling higher level of automation in future distribution systems. Future research should focus on experimental validation, simulation model refinement, and evaluation in more representative distribution network configurations.; Tässä diplomityössä tutkitaan uuden teknologian sammutuskelan soveltuvuutta yhdysvaltalaiseen keskijännitteiseen jakeluverkkoon. Yksivaiheiset maasulut ovat keskijänniteverkon yleisin vikamuoto, minkä vuoksi niiden tehokas kompensointi on tärkeä osa sähkönjakelun luotettavuutta. Työn tavoitteena oli arvioida uuden teknologian sammutuskelan suorituskykyä verrattuna perinteisiin maadoitusratkaisuihin. Työ toteutettiin simulointiin perustuvana tutkimuksena, käyttäen MATLAB/Simulink-ympäristössä mallinnettua yhdysvaltalaista keskijännitteistä jakeluverkkoa. Simulointitulokset osoittivat, että resonanssimaadoitus pienensi maasulkuvirtaa merkittävästi verrattuna suoraan maadoitettuun verkkoon. Tulosten perusteella uuden teknologian sammutuskela saavutti vastaavan kompensointikyvyn kuin tavanomainen sammutuskela. Lisäksi se pystyi säätämään induktanssiaan erittäin tarkasti kaikissa tutkituissa käyttötilanteissa. Tulokset osoittivat myös, että käytännössä optimaalinen kompensointipiste voi poiketa teoreettisesta virityspisteestä verkon epäsymmetrian vuoksi, mikä korostaa nykyaikaisten viritysmenetelmien merkitystä. Vaikka kehitetty simulointimalli kuvasi maasulkuvirran käyttäytymistä onnistuneesti, simuloinneissa havaittu odottamaton vaihejännitteiden käyttäytyminen osoittaa, että mallia on edelleen kehitettävä jännitekäyttäytymisen validointia varten. Tulosten perusteella uuden teknologian sammutuskela soveltuu hyvin keskijännitteisiin jakeluverkkoihin, joissa verkon kapasitanssi ja käyttötilanteet muuttuvat käytön aikana. Tulokset osoittavat, että uuden teknologian sammutuskela voi vähentää manuaalisen virityksen tarvetta ja samalla tukea jakeluverkkojen kasvavia automaatiovaatimuksia. Jatkotutkimuksena teknologian toimintaa tulisi validoida käytännön sähköasemaympäristössä sekä arvioida sitä nykyistä realistisemmilla jakeluverkon malleilla.

2026-01-01T00:00:00Z Moradimoayyed, Jalaluddin http://lutpub.lut.fi:80/handle/10024/172712 2026-08-10T10:30:18Z 2026-01-01T00:00:00Z

Revealing global opportunities for carbon dioxide removal through a spatially high resolved techno-economic assessment Moradimoayyed, Jalaluddin Carbon dioxide removal (CDR) will require a portfolio of options, but their availability and cost vary strongly by location. This thesis presents a spatially resolved techno-economic assessment of geological carbon dioxide sequestration (GCS), in-situ mineralisation (MININ), ex-situ mineralisation (MINEX), enhanced weathering (EW), biochar (BC), rainfed afforestation (AFRF), and desalination-fed afforestation (AFDF). The analysis was performed on a 0.45°x0.45° global grid, except for MINEX, which was assessed at regional scale. For energy-dependent options, an hourly off-grid renewable supply system based on solar PV, wind power, and battery storage was optimised for each feasible location. The estimated cumulative sequestration potential reaches 25,759 GtCO2 for GCS and 55,280 GtCO2 for MININ. EW and BC show annual technical potentials of 29 and 23 GtCO2/a, respectively, while AFRF reaches 3 GtCO2/a under the selected forest-loss drivers. Cost reductions are strongest for DAC-based CDR options before mid-century. GCSON declines from 114 to 58 €/tCO2 between 2030 and 2100, while MININ,ON decreases from 121 to 61 €/tCO2. MINEX remains more expensive, declining from 229 to 131 €/tCO2. EW and BC show more moderate cost reductions, reaching 90 and 115 €/tCO2 by 2100, respectively. AFRF gives the lowest lifetime levelised cost of carbon dioxide removal (LCOCDR), around 19 €/tCO2, while AFDF afforestation remains close to 130 €/tCO2 after 2050. Across the assessed options, the cost-optimal electricity system is mainly PV-based, with batteries providing short-term balancing and wind power contributing in selected high-wind regions.

2026-01-01T00:00:00Z Nikam, Tanaya http://lutpub.lut.fi:80/handle/10024/172711 2026-08-10T10:00:15Z 2026-01-01T00:00:00Z

Transition pathways towards a 100% renewable energy-industry system for the regional grids in India Nikam, Tanaya India's energy demand and reliance on fossil fuels are increasing rapidly, this makes the transition towards a renewable energy-industry system climate imperative and a strategic opportunity for long-term energy security. This study describes techno-economic transition pathways for India from 2020 to 2070 using the LUT Energy System Transition Model (LUT-ESTM), applying hourly resolution, five-year transition steps, and four interconnected regional grids. The model integrates the power, heat, transport, industry, and desalination sectors within a least-cost optimisation framework and compares the Best Policy Scenario (BPS), Delayed Policy Scenario (DPS), and Current Policy Scenario (CPS). The results demonstrate an accelerated transition that yields a technically feasible, least-cost system. In the BPS, renewable electricity becomes the dominant energy source, increasing from 3.3% of primary energy demand in 2020 to 92% in 2050 and 94% in 2070. Solar photovoltaics accounts for about 95% of installed electricity capacity and 94% of electricity generation by 2070, supported by wind power, storage, transmission expansion, and sector coupling. This transformation enables defossilisation, with greenhouse gas emissions declining from 2035 MtCO₂eq in 2020 to zero by 2050, while delayed and current policy pathways retain fossil fuel dependence for longer. By 2070, the BPS achieves a levelised cost of final energy of 39 €/MWh and a levelised cost of electricity of 20 €/MWh, highlighting the economic benefits of early action. Power-to-X technologies, including e-hydrogen, e-FTL, e-ammonia, and emethanol, support in defossilising hard-to-electrify transport and industry segments. These findings show that accelerated renewable energy deployment, sector coupling, and system flexibility can deliver a least-cost, climate-compliant, flexible, and cost-effective energyindustry future for India.

2026-01-01T00:00:00Z Khalid, Muhammad Umar http://lutpub.lut.fi:80/handle/10024/172710 2026-08-10T09:00:12Z 2026-01-01T00:00:00Z

Electromagnetic assessment of a 2.7 MW, 15 000 rpm axially laminated anisotropic synchronous reluctance machine as an alternative to an induction machine Khalid, Muhammad Umar This thesis presents the electromagnetic design and comparative finite-element analysis of two magnet free high-speed machine topologies: an induction machine (IM) and an axially laminated anisotropic synchronous reluctance machine (ALASynRM), designed for a rated operating point of 2.7 MW and 15 000 rpm. Two-dimensional transient finite element models are developed in Altair Flux, and the machines are evaluated in terms of torque, magnetic flux density, saturation, harmonic content, electromagnetic losses, efficiency and power factor. Parametric studies address the rotor bar diameter and slit length of the IM and the rotor layer ratio, current angle and air-gap length of the ALASynRM. The optimized IM achieves an estimated electromagnetic efficiency of 98.91%, a power factor of 0.815, total electromagnetic losses of 29.85 kW and current density of 10.39 A/mm². For the ALASynRM, a current angle of 70° and an air gap of 4 mm were selected as the best investigated electromagnetic compromise. This configuration achieves an estimated electromagnetic efficiency of 98.25%, a power factor of approximately 0.74, total electromagnetic losses of 48.37 kW, a saliency ratio of 6.34 and a current density of 10.22 A/mm². The comparison shows that the IM provides lower electromagnetic losses and higher efficiency and power factor, whereas the ALASynRM produces substantially lower torque ripple. The results identify the principal electromagnetic trade-offs between the two magnet free topologies for multi megawatt high speed machine applications.

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