Universal Absolute Stability Criterion for Single-Phase Grid-Following Inverters Equipped with Orthogonal-Normalization-Based Grid Synchronizer

• Published in: IEEE transactions on power electronics Vol. 38; no. 7; pp. 1 - 10
• Main Authors: Cheng, Cheng, Xie, Shaojun, Xu, Jinming, Qian, Qiang
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: absolute stability; grid synchronizer; Grid-following inverter; Impedance; Inverters; large-disturbances; orthogonal normalization; Phase locked loops; Power system dynamics; Power system stability; Stability analysis; Stability criteria; Synchronization
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2023.3262860

The stability problem of grid-following inverters has been widely investigated. Nevertheless, existing literature has not yet proposed a strict stability analysis method for the overall grid-following inverter system with nonlinear nature. Focusing on single-phase systems, by using frequency-domain nonlinear theory, this article proposes a universal absolute stability criterion for the single-phase grid-following inverters (SGFIs) equipped with orthogonal-normalization-based grid synchronizer. It will be shown that a SGFI will be absolutely stable under small- and large-disturbances if both the traditional impedance criterion and the synchronous nonlinear criterion are satisfied. The usefulness and applicability of the proposed new criterion is demonstrated by a case study of the conventional LCL-type SGFI system. Finally, the theoretical analysis is fully supported by a series of steady-state and transient experimental tests.