The compliant integration of (renewable) power sources in MV or LV grids and the impact on grid reliability

The integration of renewable energy sources in medium and low voltage grids is a not to be underestimated challenge for operators and planners both of the plants as well as of the grid operators. Questions concerning the compliance with the acceptable voltage limits, transmission capacity, active and reactive power balance, grid stability, economic efficiency and environmental benefits have to be answered. In addition, the use of additional equipment suggests that the reliability of the system could decrease. In this paper, on the one hand, an effective method to forecast voltage fluctuations caused by decentralized generation units in suburban distribution grids is presented based on a quick graphic determination method and is compared to exact load flow simulation results. On the other hand the load flow model is used to calculate the influence of the integration of the decentralized power generation units and grid restructuring measures on the system reliability. By way of an exemplarily medium and low voltage grid, these questions are answered.