The role of renewable energy sources are getting more and more important. The world realized, that we must take care of the environment. Thanks to that, many rules are made, for example in the European Union. They ordered Hungary, that the renewable energy must be at least 13,6 % of the total generated electrical energy. In my thesis, I examine the exactly these kind of energy generated small power plants, especially their connection to the grid and the caused grid effects. I will discuss the role, the effects and the licensing requirements of the household size power plants connected to the low voltage grid and small size power plants with rated power ranging 50 kVA - 50 MVA connected to the high voltage or medium voltage distribution grid. The main grid effects are the voltage level change, flicker, asymmetry of the current, the power factor and the circuit power.
I particularly investigated one of the strictest rule of the EN 50160 standard, which requires, that voltage change at the PCC (connection point) must be below 2% of the nominal voltage in case of medium voltage level and 3% in case of small voltage level.
Finally, I analysed the effects of the low voltage regulating transformers to the voltage profile of the distribution feeder.
For these studies I used power system simulation tools, namely the Power World and the NePlan software packages.