This book - written as a textbook for students of engineering - is designed for the Norwegian Power Markets course which is part of the Energy and Environment Master's Program and the recently established international MSc program in Electric Power Engineering. As the title indicates, the book deals with both power system economics in general and the practical implementation and experience from the Nordic market. Areas of coverage include: -- Restructuring/deregulation of the power supply system -- Grid access including tariffs and congestion management -- Generation planning -- Market modeling -- Ancillary services -- Regulation of grid monopolies. Although Power Systems Economics is written primarily as a textbook for students, other readers will also find the book interesting. It deals with problems that have been subject of considerable attention in the power sector for some years and it addresses issues that are still relevant and important.