Integration of renewable energy sources to the power system

This paper discuss about the influence and problems caused by integration of renewable energy sources to the power system. Paper analyzes the problems of undesirable power flows that results from difficult predictability of production from these power plants. These impacts were modelled by means of program MODES on standardized power system of IEEE 39 bus System. The difference between sunny and cloudy days is compared in graphs and there is calculated that difference in percentage. Variability of wind affecting the wind power plants is also plotted in graphs. Overloading the power lines and transformers cause their outage and the imbalance between production and consumption, what shows the output of simulation.