Exploiting the potential of wind turbines to provide frequency support

Abstract

The wind energy technology emerges as one of promising techniques for satisfying growing power demand as well as reducing carbon dioxide emission. During recent years, the penetration level of wind energy has experienced continuous growth. However, compared with conventional power plants, the characteristics of wind power plants are different, and thus the wind power plants can impose significant challenges on the power system control and operation. In order to maintain the stability of power system, some transmission system operators have stipulated that the wind power plants are required to regulate their performance. According to the technical rules specified by these system operators, the wind power plants ought to participate in voltage control and frequency regulation if necessary. To fulfill these requirements, various control schemes applied in wind turbines have been put forward. The research in this thesis aims at developing new control schemes exploiting the potential of each variable speed wind turbine for frequency control. The research background and motivation are introduced in Chapter 1. Chapter 2 summarizes the technical requirements for wind power integration issued in recent years. The classical modelling of variable speed wind turbine and relevant control strategies are illustrated in Chapter 3. Based on a comprehensive review on the frequency control strategies designed for individual wind turbine, combined frequency control schemes enabling the variable speed wind turbine to provide frequency response are proposed in Chapter 4. Chapter 5 reveals that the control methodology presented in Chapter 4 can also be implemented in the offshore wind farm connected to VSC-HVDC system. The simulation results verify the effectiveness of the proposed frequency control schemes. Conclusions and future scope are provided in Chapter 6.