This thesis presents an analysis of voltage conditions in a low-voltage distribution network under increasing integration of photovoltaic (PV) systems and battery energy storage systems. In recent years, the number of households installing PV systems on their buildings has grown rapidly, driven by policies promoting sustainable development, legal incentives, and subsidized self-sufficiency schemes. While such distributed generation contributes to greater energy independence for end users, it also introduces new challenges for the operation of distribution networks, which are often not fully adapted to such operating conditions. Primary concerns include maintaining voltage stability and avoiding transformer overloading.
As part of the thesis, a simulation model of a real low-voltage network segment was developed. The model includes a transformer station, busbars, distribution lines, loads, photovoltaic systems, and lithium-ion battery storage units. Using simulation tools, three different operating scenarios were analyzed: a baseline case without local generation, a scenario with integrated PV systems, and a scenario with the addition of battery storage. Each scenario was examined separately for both winter and summer conditions, as energy production and consumption vary significantly with the seasons.
The analysis focused primarily on monitoring voltage profile changes across the network and transformer loading under different operating conditions. In addition to the simulation results, the thesis also includes explanations of the technical operation of battery storage, the principles of energy management and storage, and the basic parameters of voltage quality and regulation in low-voltage grid systems. The study also considers aspects of long-term system reliability and sustainability, including the recyclability of installed components.
The main objective of the thesis was to demonstrate how lithium-ion battery energy storage can contribute to more reliable, and efficient operation of low-voltage networks with a high share of distributed generation, and to assess the feasibility of their integration into future networks without the need for major infrastructure upgrades.
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