2 research outputs found

    Driftmodellering av saltvattenbatteri för kapning av effekttoppar

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    There is a power deficit in Uppsala's power grid. Municipal companies have an obligation to contribute with solutions to the power deficit. Skolfastigheter AB have therefore installed an environmentally friendly salt water battery in one of their properties. The goal of this project is to create an algorithm for controlling the battery so that it cuts power peaks at a preschool in Uppsala. The algorithm is created based on economical, environmental, and political aspects. A model of the battery is constructed in which technical specifications for the real battery are used. The model is tested using historical power usage data from one of Skolfastigheter AB's preschool properties. The resulting model successfully cuts the facility's power peaks as intended. The model succeeds even when the input data are varied. The algorithm is also applied in reality and controls the battery via a programmable logic controller (PLC). The goal of cutting power peaks is also met with the PLC. Simulation of the battery cuts power peaks more optimally than when the algorithm is implemented in reality. To improve the model, data from more preschools as well as possibilities to perform more experiments are required. The usage of programmable power storage is today not economically profitable. Batteries do however contribute to reaching Uppsala municipality's environmental and climate goals. Batteries also contribute to a more robust energy system where fossil power reserves can be avoided

    Harmonics in the low voltage grid : The impact of a largescale introduction of solar panel systems and electric vehicle charging

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    The number of solar panel systems and electric vehicle charging in the low voltage grid is increasing rapidly, due to climate- and environmental targets. These nonlinear loads inject harmonics into the grid, which could impact power quality as well as the wear and life of power grid components, such as transformers and cables. The Swedish network operator Ellevio wants to investigate the possible effects that can arise from a largescale introduction of this equipment in the grid, in terms of harmonics. The aim of this master thesis has been to evaluate the compatibility of equipment emission standards and requirements for power quality, and through different calculation methods assess the potential impact from high penetration of devices in the same network. The results show that converters of both EV and PV are able to keep emission levels well below the equipment standard limits. Even by full penetration of a network the aggregated effect of these loads will not alone have a significant impact on neither power quality nor components in terms of wear, losses or capacity. However, in networks experiencing unusually high background levels in combination with high emissions from other loads, the PV and EV emissions could be a contributing factor to a state where individual transformers would be affected or single harmonic voltage limits would be violated. This is considered a very rare case, and thus not something that would serve as a basis for the dimensioning of the low voltage grid. Instead, increased knowledge will help assessing such a scenario and give better support for solving the individual cases that do arise
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