The present book addresses not only the fundamentals of reactive power compensation in low and medium voltage networks but also the following questions: construction, design, and operation of capacitors and compensation systems, plant technology, long-term stability and aging of capacitor systems, assessment of supply quality according to DIN EN 50160 and other standards, costs and economic aspects of compensation systems, improvement of voltage quality through filters and compensation systems, use of passive and active filters, basics of using FACTS (Flexible AC Transmission Systems), as well as a new chapter on the assessment of supply quality. It includes numerous application and calculation examples.