Combined central and local control of reactive power in electrical grids with distributed generation

The wide spread of distributed generation from renewable power sources may cause severe degradation of electricity quality due to its hardly predictable nature. In order to maintain the desired electricity quality, new actuators and advanced control techniques needs to be developed and integrated in the grid. The reactive power injection of photovoltaic (PV) inverters provides an effective mean for the control of voltage levels and their fluctuation. This paper describes a combined central and local control scheme for the reactive power. The use of local controllers based only on local measurements enables a fast reaction of the controllers on changes in generated and consumed powers, while the central optimization of their parameters ensures an optimal use of the resources and minimization of losses. MATLAB simulations prove the concept for a realistic distribution grid.