An Estimation Method for PV Hosting Capacity of Distribution Grids

Sammanfattning: The Swedish Energy Agency has a target to increase solar photovoltaics (PV) power production by up to 5-10% of the total electricity demand by the year 2040. The PV potential for the residential market is high and its contribution to the total installed PV capacity is expected to increase significantly. The technical requirements should be met to keep high reliability and good power quality at the customers, therefore, it is important for planning reasons to proactively find the maximum amount PV power that can be connected at each low-voltage network without violating the performance of the grid. This amount is known as the hosting capacity. A method for PV hosting capacity estimation by taking overvoltage and transformer overload as performance indices was developed in this thesis. The method does not require any knowledge about the topology of the network. The overload hosting capacity can be estimated for any combination of customers having PV power and for the overvoltage hosting, the minimum at each penetration level can be estimated. The method was implemented on four low-voltage networks located in a typical Vattenfall medium-voltage network and the comparison of the estimation results to a power flow simulation showed good correspondence. It was shown how the impact of PV power in adjacent secondary substations can be accounted for. Using SS-EN50160 voltage limits, the studied networks were able to handle 3-7 times the PV penetration level needed (8 kWp at 20% of the customers) to achieve the national goal in Sweden without grid investments.