Abstract
Extensive electrification has created an increased demand of electric energy and power. Congestion issues are expected to become more common as transmission and distribution grids reach their capacity limits. One of the regions in Sweden that has experienced this already is Uppsala. The distribution system operator, Vattenfall Distribution has initiated an R&D project that connects a 5 MW/20 MWh Li-ion battery energy storage system to temporarily ease the grid congestion. This study covers an analysis of grid voltage fluctuations using a largescale battery in a distribution grid. The power quality is examined at the 10 kV connection point of the storage, where voltage and power flow are presented. Also, an example of how value stacking may be implemented is illustrated by adding a secondary service during the year. The test results indicate no significant distortion of the voltage level at the measurement point during smooth ramping. It can be concluded that smooth ramping of the BESS has very low or no impact on the local power quality, and additional services should be provided during the year to create several revenue streams. Future studies could focus on fast ramping of the BESS and stacking services in an intra-season perspective.
Highlights
Outlooks and forecasts regarding the electricity demand in 2030 varies depending on several assumptions, one official prediction though is made by the International Energy Agency (IEA) saying that % of the global final energy consumption could be met by electricity – an increase from approx. 300 TWh in 2018 to 27 500 TWh in 2030 [2,3]
If the results show no significant effects on the power quality, there should be no significant effects during CoordiNet service provision either
It is clear from the three subfigures (a)-(c) that the voltage level remains stable during all three events of the test cycle
Summary
Depending on the prerequisites of the already existing grid infrastructure, actions will be required to maintain stable operation as the demand for electric energy and power increases. The annual increase in demand puts the grid expansion rate on its edge. Congestion issues have arisen in regions where the demand has increased faster than the grid expansion has been planned for. The transmission system operator (TSO) has not been able to raise subscription levels to regional distribution system operators (DSO) in short time, which puts the DSOs in a tough situation with increasing queues for connection requests. In Sweden, the electricity distribution companies are under legal obligation to connect new customers, but this may be delayed if congestion issues arise. Demand response (DR) and energy storage systems (ESS) are two commonly considered solutions due to the short time required going from seed to flower, and when looking from a cost perspective
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