Reactive power control in low voltage distribution grids: Comparison of centralized and decentralized Q(U)-controller designs based on probabilistic power flow analysis

The massive integration of new decentralized generators in distribution grids has led to voltage problems, especially in the low voltage (LV) grid, where most of the generators are connected. One possibility to solve this problems is the introduction of voltage dependent reactive power control Q(U) which can influence the voltage level. This paper evaluates different decentralized Q(U)-droop controller parametrization methods against the centralized controller design, which is assumed to be optimal in terms of minimizing the provided reactive power while solving the voltage problem. The influence of all controllers on the nodal voltage and line usage rate is calculated via probabilistic power flow analysis. Parametrizing the decentralized controller with results of the centralized controller yields a cost effective alternative to centralized reactive power control.