Optimal design and control implementation of unified power quality conditioner

Abstract

In this chapter, the most common power quality problems, i.e., the supply voltage sag and swell, supply voltage harmonic distortion, current harmonic distortion of nonlinear load, and low power factor are discussed in terms of their causes, damages, and disadvantages. Generally, the causes of the aforementioned power quality problems include the overload, sudden change of the loads, connection and disconnection of large loads, connection of large capacitor banks, nonlinear loads, increase of the magnetizing current, etc. These power quality problems may cause the overheat, overvoltage, or overload in the power electrical machines, capacitor banks, transmission cables, distribution cables, bus bar, and connecting lug; generate mechanically resonant in the electrical panels; and cause inductive interference in the neighboring telecommunication lines. Furthermore, the IEEE recommended standards of limiting the power quality problems are clarified. In these recommended standards, the power acceptability curves, i.e., the CBEMA curve, the ITIC curve, and the SEMI F47 curve are utilized to limit the system voltage sag and swell. The recommended voltage and current harmonic limits are discussed in IEEE Standard 519-1992 and 2014. The power supply companies set the acceptable power factor limit to 0.9 and above for the customers.