Power estimation of induction generators fed from wind turbines

Wind energy has good potential for reducing the environmental impact and cost of electricity generation in diesel based stand-alone systems (mini-grids). However, due to the stochastic nature of wind and the highly variable loads typical of remote communities, the diesel power plants can be subject to significant variation in the power demand. This can create large variations in the grid frequency and also make the diesel gensets operate at low load what can lead to carbon build up in the engines and increased maintenance costs. Some power electronic based wind turbines can provide frequency support to mitigate these problems but might be too costly for operation in small mini-grids. Conversely, there is the fixed-pitch fixed-speed induction generator based (type 1) wind turbine which does not allow any active control but presents low capital and maintenance costs. In this paper, an approach for obtaining the power vs. grid frequency characteristics of a type 1 wind turbine is described and validated experimentally. It shows that the power injected into the grid by a type 1 wind turbine reduces as the grid frequency increases. Therefore, it can help with frequency regulation in a passive way.