Effects of the Reactive Power Injection on the Grid—The Rise of the Volt/var Interaction Chain

Abstract

The major challenge to increase the decentralized generation share in distribution grids is the main-tenance of the voltage within the limits. The inductive power injection is widely used as a remedial measure. The main aim of this paper is to study the effect of the reactive power injection (by what-ever means) on radial grid structures and their impact on the voltage of the higher voltage-level grids. Various studies have shown that, in addition to the major local effect on the voltage at the in-jection point, the injection of the reactive power on a feeder has a global effect, which cannot be neglected. The reactive power flow and the voltage on the higher voltage level grid are significantly affected. In addition, a random effect is introduced by the DGs which are connected through inver-ters (using wind or PVs). Although their operation is in accordance with the grid code, a volatile reactive power flow circulates on the grid. Finally, this study proposes the implementation of the " Volt/var secondary control " interaction chain in order to increase the distributed generation share at every distribution voltage level, be it medium or low voltage, and at the same time to guarantee a stable operation of the power grid. Features of Volt/var secondary control loops ensure a resilient behavior of the whole chain.