Microgeneration of PV power and its impact on power quality in the distribution grid

Abstract: This bachelor thesis examines the impacts of installed microgeneration of PV power in the distribution grid. The thesis examines the selected distribution grids power quality and how it is affected in terms of exceeding currents, voltages and reverse power flows and how the future trend of microgeneration of PV power will develop. A case study is made on Gotland with the support of the distribution grid owner, GEAB. Three of GEAB's distribution grids with different customer configurations and grid structures are being used to create different case scenarios. The production from the PV plants is calculated with production data from a project that GEAB performed with PV plants but dismantled in 2016. The Newton-Raphson power flow method is used to run the simulations of the grids with different amount of installed PV power. The results show that exceeding maximum current is the first parameter to limit and affect the power quality for all grids. After this the three grids can handle different amounts of installed PV power with respect of the remaining parameters. The simulations also show that losses in the grid are reduced due to installations of PV plants, although their small magnitude do not make them a significant aspect to consider when evaluating microgeneration in the distribution grid. When comparing to future scenarios it is concluded that the grids are dimensioned to handle a various amount of installed microgeneration without the power quality being affected.  To analyse the sensitivity of the results a sensitivity analysis is performed on the slack node voltage by alternating the voltage level. The result indicates that a higher slack node voltage gives more exceeding voltages for the city power grid and the two rural grids.