A New Virtual Harmonic Impedance Scheme for Harmonic Power Sharing in an Islanded Microgrid

• Published in: IEEE transactions on power delivery Vol. 31; no. 3; pp. 936 - 945
• Main Authors: Sreekumar, Preetha, Khadkikar, Vinod
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Control systems; Data buses; Digital signal processors; Digital transmission; Distributed generation; Droop control; Electric potential; Harmonic analysis; harmonic power sharing; Harmonics; Impedance; Inverters; islanding; microgrid; Microgrids; Power harmonic filters; Reactive power; Strategy; virtual impedance; Voltage; Voltage control
• ISSN: 0885-8977; 1937-4208
• DOI: 10.1109/TPWRD.2015.2402434

This paper proposes a control strategy for harmonic power sharing in an islanded microgrid, without affecting the voltage quality at the load bus. The harmonic power distribution in an islanded microgrid depends on the line impedance. The proposed control strategy employs negative virtual harmonic impedance to compensate for the effect of line impedance on harmonic power delivery. The influence of mismatched line impedances on nonlinear load distribution is minimized by virtually varying the effective line impedance at harmonic frequencies. The fundamental active and reactive power sharing is implemented using the droop technique and the proposed method operates independently, without affecting the linear load sharing. Furthermore, a new droop method, called Zh - H droop, is also proposed to estimate the virtual harmonic impedance value adaptively. The proposed concept of negative virtual harmonic impedance and Zh - H droop is validated using simulation and digital signal processor-based experimental studies.