Investigation of dynamics, control, power quality and fault response of a MW-size wind generator with integrated storage

• Main Author: Strachan, Nicholas P. W.
• Published: University of Aberdeen 2010
• Subjects: 621.31; Wind turbines : Electric fault location : Wind power : Power electronics
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.521262

a control, power quality and stability perspective. This is chiefly due to the future influence on power system behaviour resulting from the rapid cumulative growth of grid integrated wind power, and the improved control characteristics afforded by modern variable speed wind power generators. There is consequently strong motivation to enhance the inherent control robustness, power quality and fault-ride-through characteristics of modern wind power generators. By so doing, the attributes essential for power system operation regarding security of supply, reliability, and power quality can be assured. The work presented in this thesis employs a two-fold methodology in order to improve the inherent control, power quality and fault tolerance characteristics of a modern wind power generator based on a 2MW medium-voltage directly-driven permanently-excited architecture employing full-scale power conversion. Firstly, due to the complexity of modern wind power generators, accurate and complementary detailed non-linear (circuit orientated) and linear analytical (state-space based) wind generator models are developed. Collectively, these facilitate a wide range of detailed transient and smallsignal, control, stability and fault analysis studies. Ultimately, this facilitates the means by which advanced AC voltage controls are developed that significantly extend the wind power generator stable operating range for grid strength variations (grid impedance variation). Secondly, a supercapacitor based electrical energy storage system is designed and integrated within the developed wind generator models in order to facilitate the means by which fault-ridethrough characteristics and power quality can be improved. Fault-ride-through characteristics are ultimately improved by absorbing a proportion of generated power in the integrated storage system during grid-side faults. Power quality is ultimately improved by effectively buffering wind speed fluctuations in the integrated storage system so that a ‘smoothed’ version of the generated power results at the wind generator terminals.