Photovoltaic hosting capacity study for a residential area in Uppsala using a synthetic low voltage network

Sammanfattning: With the growing acceptance of photovoltaic (PV) systems globally including Sweden, an increasing number of PV systems has continually been installed all through Sweden. In this study, a selected residential area in Uppsala Sweden is considered as a possible site for PV system installation. Due to the intermittent nature of this energy source and the disturbances it causes to the grid, there is therefore the need to determine the amount of PV that can be accommodated by the already existing grid without any adverse effect to it. This is known as hosting capacity (HC). The HC signifies the level of risks the network operator as well as customers are willing to take with regard to the stability of the grid network. Many possibilities exist by which this can be done which are well discussed later in this report. However, the deterministic method is used in this work. For an effective determination of the HC, the DIgSILENT Power Factory 2021 is used to simulate a synthetic network assumed to be similar to that of the area studied. A parametric analysis is also done to as certain the impact some network variables would have on the limit of PV systems a grid network can accommodate. The results of the study showed that under 0 % penetration, the grid network is stable and no violations witnessed neither from the network with 800 kVA transformer considered as the main network in this study nor that with 500 kVA used for the parametric studies. However, the loadings on the two transformers varied by about 15 %. Integrating PVs into the grid network introduced some level of instability which increases as the size of the PVs increases. This shows the need to peg the PVs’ size to a certain maximum to be able to have control over the grid network. Customers are allowed to install lower sizes but not more than this maximum. The results also showed that changing the transformer size do not affect the nodal voltages nor the cable loadings in the network provided all other parameters remained the same. The only impact is on the transformer loading, with smaller transformers experiencing higher loading condition. This study serves as a basis to determine the initial range of PV sizes customers are allowed to install in the area studied in Uppsala Sweden.