Book excerpt: Power quality describes a set of parameters of electric power and the load’s ability to function properly under specific conditions. It is estimated that problems relating to power quality costs the European industry hundreds of billions of Euros annually. In contrast, financing for the prevention of these problems amount to fragments of these costs. Power Theories for Improved Power Quality addresses this imbalance by presenting and assessing a range of methods and problems related to improving the quality of electric power supply. Focusing particularly on active compensators and the DSP based control algorithms, Power Theories for Improved Power Quality introduces the fundamental problems of electrical power. This introduction is followed by chapters which discuss: ‘Power theories’ including their historical development and application to practical problems, operational principles of active compensator’s DSP control based algorithms using examples and results from laboratory research, and the key areas of application for these methods and suggested practical solutions. Power Theories for Improved Power Quality is a key study resource for students in engineering and technical degrees as well as a reference for professional and practitioners in the electrical energy sector working with power quality.