Power systems with local PV-generation and battery storage for peak shaving to provide flexibility services to the utility grid

University essay from Uppsala universitet/Elektricitetslära

Abstract: Due to the increased demand for electricity in recent years and the estimated demand in the future it has become clear that the capacity of the Swedish electrical grid is insufficient, and the grid is not able deliver the amount of power that is demanded by the market. The crucial points in the grid where the grid capacity is insufficient could be several. It could be in the transmission system but also at locations in the distribution system, such as congestion points for residential areas for example. For the grid to be able to meet the new demands large investments are needed to renew electricity grid. This will cost a lot of money and it will take several years before the grid capacity is up to scale. A problem is that the grid must be dimensioned for the highest power peaks that could be expected even though these might occur just a few times every year. As a response to this a new market for flexibility solutions in the grid has arisen. An example of a flexibility solution is a method called peak-shaving. Peak-shaving is a method that levels out the overall load-profile and so on reduces the highest power-peaks. The aim of this thesis was to investigate how integrated power systems with battery storageinstalled in household villas could implement peak-shaving with the purpose of providing a flexibility-service to the grid. The study includes theoretical simulations, as well as practical experiments and performance analyses of installed systems. The study also includes an investigation how the current price model and tax rules create incentives for costumers to provide this flexibility service. Firstly, a theoretical simulation model in MATLAB was developed that could make a virtual simulation of the result from implementation of peak-shaving based on historical data of the power profile of the household. After this, experimental tests were conducted for three households where peak-shaving was implemented. With the data from the experiments the performance and potential deficiency of the installed systems could be analysed. With the recorded data from the experiments and with collected data of the hourly based price for electricity it could be studied what impact peak-shaving has on the costs for the household and so on what incentives the price model and tax rules creates to implement peak-shaving.What could be concluded in the study was that peak-shaving has a good potential to reduce power-peaks and provide flexibility to the grid. The results from the tests showed that the power-peaks were able to be reduced but the power systems did however have some observed deficiencies that reduced their performance. It could also be concluded that the current price model and tax rules often increases the costs when implementing peak-shaving and so on create poor incentives to provide this flexibility service.

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