Mode of oscillation based islanding detection of inverter interfaced DG using ESPRIT

• Published in: Electric power systems research 2021-11, Vol.200, p.107479, Article 107479
• Main Authors: Kumar, Avinash, Panda, R.K., Mohapatra, Abheejeet, Singh, S.N., Srivastava, S.C.
• Format: Article
• Language: English
• Subjects: Distributed generator; ESPRIT; Islanding detection; Mode of oscillation; Non-detection zone; Power quality
• ISSN: 0378-7796; 1873-2046
• DOI: 10.1016/j.epsr.2021.107479

•A novel active islanding detection method for IIDGs is proposed using a low-frequency current injection in the DG controller.•Post injection, dominant modes of the PCC frequency deviation from ESPRIT confirm islanding.•q axis injection is suggested over the d axis injection due to the low impact on PQ.•The method is free of thresholds and applicable to any IIDG with a _xed operation time of 0.12  s. Islanding detection of Inverter Interfaced Distributed Generators (IIDGs) is a major aspect of microgrid automation. Most islanding detection techniques, either active or passive, are developed based on threshold settings, and hence, have limited application. Detection of the mode of oscillation in frequency signal measured at the Point of Common Coupling (PCC) using the Estimation of Signal Parameter via Rotational Invariance Technique (ESPRIT) is presented in this paper for islanding detection of IIDGs. A low-frequency current injection disturbance is injected in the conventional dq controller of the IIDG. The frequency deviation is estimated using ESPRIT for signal parameter estimation. The Total Harmonic Distortion (THD) due to the low-frequency disturbance injection is also evaluated for both d axis and q axis. The proposed method is tested in Real-Time Digital Simulator (RTDS) on a test system with multiple DGs, and an unbalanced microgrid, at various operating conditions, such as, different quality factors of loads, random loading, faults, and switching transients in the microgrid. The simulation results indicate that the proposed method for islanding detection of IIDGs completely eliminates the Non-Detection Zone (NDZ), with negligible impact on Power Quality (PQ), and is independent of any threshold settings.