I. Introduction
With the widespread applications of advanced power electric technologies, such as switching power supplies and adjustable speed motor drives, among others, harmonic currents are increasingly being injected into power systems causing power quality degradation. Harmonics increase power system losses, damages sensitive loads, causes excessive heating in rotating machinery, creates significant interference on communication systems, and generates noise in regulating devices and control systems. In addition, the system frequency may deviate from its nominal value due to power imbalance between generation and load demand. Therefore, measuring grid harmonics, in an accurate and efficient manner, has turned into a major challenge [1]–[3].