Driftmodellering av saltvattenbatteri för kapning av effekttoppar

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

Utjämning av effekttoppar från avisning av tåg i Luleås fjärrvärmenät

In the south-east part of the district heating network in Luleå, LKAB:S facility for de-icing their trains transporting iron ore is situated. The de-icing is done by sprayning the trains with hot water. The hot water is stored and heated in a basin, heated by district heating. When the de-icing starts the temperature in the basin drops and to restore it more heat is supplied from the district heating network. This results in peaks in the heat demand which causes high flows in the district heating system. The pipes in the district heating system are under-dimensioned and the high flows thereby causes high pressure gradients and a low pressure difference in the district heating grid. The objective of this project is to even out the peaks in the heat demand from the de-icing facility in order to minimize the maximal flows and improve the pressure difference in the grid. This was done by developing a heating strategy for the facility, using the basin to store energy as hot water. The strategy resulted in lower maximal peaks, where the highest peak during the studied period was reduced from 2430 kW to 1560 kW. In order to improve the return temperature in the gridfrom the facility a new heat-exchanger was dimensioned. The impact of these changes on thedistrict heating grid in Luleå was examined by simulations of the grid in the simulation software Netsim. These simulations showed that the pressure difference at the de-icing facility increased from 50 kPa with the current system to 200 kPa with the proposed changes. An investment assesment was conducted with respect to the heat exchanger for LKAB. It shows that the yearly flow costs are reduced and that the investment would be repayed within one to three years.