Voltage Stability of Large Power Networks with a Large Amount of Wind Power

The article presents results of voltage stability investigations carried out on a large power network model. Presumably, around 50 per cent of electricity consumption is covered by wind turbines and by local combined heat and power (CHP) units. In investigations, a distinction is made between local wind turbines and those in a large wind farm subject to the Grid Specifications of the transmission system operator (Eltra, 2000). The main concerns of maintaining power system operation are (i) a risk of significant power loss due to tripping of local units and (ii) a risk of overvoltage at the periphery of the power network. This is contrary to previous investigations predicting that the main concern should be a risk of voltage collapse (Bruntt et al., 1999). As demonstrated, voltage collapse does not occur, because local wind turbines will trip when abnormal grid operation is indicated. This "eliminates" the problem of voltage-collapse. On the other hand, this introduces new problems with regard to (i) establishing power reserves and (ii) protecting the power network against overvoltage.