Fig. 4: Expansion plans in real power grids cause non-local overloads of the grid.
a A simulation of the German power grid is performed using a full-scale market where the color code shows the current relative to the thermal limit current: Yellow indicates high loads, while orange or red indicates an overload, see Methods for details on the simulation model. b Zoom on the North-western part of the German power grid in its base load case. c Including an AC expansion (blue oval) causes higher loadings (orange oval). The color code of the lines denotes the increase in load. Some lines are now close to their overload condition. d Including a long-range DC line (blue oval), again causes some lines to be close to their overload condition (orange oval). e, f We compare the proportional loading (actual loading divided by max load) of the most highly loaded lines before and after enhancing existing lines in both the AC (e) and the DC (f) extension scenario. The horizontal red lines indicate the transition to the overloaded state. In and Pn give the maximal current or power as designed for normal operation, i.e., any current I > In or power P > Pn signals an overload. Maps were created using the Quantum GIS Project and the Mapping Toolbox in MATLAB.
