Sensitivity analysis of low voltage distribution grid in rural areas with high penetration of PV systems
Abstract
PV systems are one of the most increasing renewable energy sources globally. In Norway, PV systems increase in amount and size, and it is becoming more critical to have solid knowledge in incorporating them into older grid systems.
This master thesis investigates the impact of PV systems on the low voltage grid and the impact on the power quality terms. The objective is to evaluate the PV capacity regarding voltage limits, THD, and thermal overload to describe a grid investment threshold.
The utility company Lede AS provides this thesis with necessary data for consumer measurements and network information system. Four study cases of existing grid systems from rural areas with few customers are modeled using PowerFactory. These grid systems represents the most challenging area for the utility company to incorporate PV systems.
In order to understand the PV capacity in these grids, the four study cases evaluate four different scenarios. The first two scenarios will investigate the PV capacity in specific scenarios, and the last two will investigate the impact on PV capacity by reinforcing the grid. Customers close to the substation and generally farms have a high PV capacity. Changing the transformer has little effect in improving the PV capacity of the circuit. Changing the feeding lines to cables with higher capacity have a better effect on improving the PV capacity in the circuits.
The simulation results show that the parameter voltage variation most often limits the PV capacity in a rural grid area with high PV penetration. The thesis proposes an equation with a consideration method for the DSO to decide if the grid needs investment regarding integrating new prosumers into the grid. In Lede AS' grid area, 746 of 7172 substation circuits have a higher risk of needing an upgrade because of PV systems.