Power capacitors and the improvement technology of electric power quality

Power capacitors have contributed greatly to the effective use of electric power, such as network voltage adjustment, line loss reduction and power factor correction. And harmonic filters have contributed greatly to the power quality improvement. Then, by the ripe capacitor application technology and the development of power electronics, they have evolved into such static var compensators (SVC) and voltage dip compensators. In recent years, the fluctuation of voltage and frequency and the increase of harmonics, due to the rapid increase of renewable energy power such as PV and wind power have occurred, and additionally the over-lead power factor or the Ferranti effect due to increase the use of inverter technology in load devices and energy saving have occurred. The countermeasure to these issues by the changes of sources and loads in power systems has been requested for power capacitors and their applications. Considering these circumstances, in this commentary, while investigating the influence to power quality by the over-capacitor installation and by the change of power supply and load, and introducing the evolution and development by power capacitors and their applied technology, the left-behind subjects are described. © 2015 The Institute of Electrical Engineers of Japan.