This book is based on teaching material developed over a five-year period to support a one-year course at University of Strathclyde on Wind Energy Systems. It aims to prepare graduate students for a PhD in wind energy research and a career in the wind sector. It covers all aspects of wind energy systems including the wind resource, the technology and design of modern wind turbines including control and power conversion, the integration of wind power in to power systems and also the socio-economic context. There are a limited text books on wind energy for students that provide a balanced coverage across the different fields of engineering and science.