Interpreting IEEE STD 519 and meeting its harmonic limits in VFD applications

IEEE Std 519 was first introduced in 1981 to provide direction on dealing with harmonics introduced by static power converters and other nonlinear loads so that power quality problems could be averted. It is being applied by consulting engineers and enforced by utilities more frequently in recent years as the use of variable frequency drives and other nonlinear loads has grown. Two of the more difficult aspects of applying IEEE Std 519 are (j) determining an appropriate point of common coupling (PCC) and (ii) establishing a demand current at the design stage. This is because the standard does not provide a concise definition of the PCC and the recommended definition of demand current is a value that can only be determined by measurements taken after installation. This paper represents the authors'-best interpretation of IEEE Std 519. It attempts to provide clarity in the determination of the PCC and offers a means by which IEEE Std 519 can be applied at the design stage when the precise demand current is unknown.