General estimation of reactive power control of DG sources on voltages in distribution grids

Nowadays, DG sources have a major effect on the operation of distribution grids. Due to in the future even more power will be fed in decentrally, it is imperative that small producers offer system services like reactive power provision and voltage control in the distribution layer. Previous work dealed with the general estimation of the impact of different types of DG sources on voltage bounds and grid losses depending on the installed capacity and the location in the grid. It was seen that DG sources at first positively effect grid losses but after exceeding a certain amount which is almost reached nowadays grid losses will virtually always rise. Generally, injected power leads to higher voltages especially in the low voltage layer. It was shown that the most limiting constraint of DG sources is not the transport capacity of the grid but the voltage tolerance band. In this paper, different strategies to keep the voltage within the bounds by adjusting reactive power injection of DG sources are presented. It is proven that a voltage-dependent control strategy produces the best results.