A Fast and Precise Grid Synchronization Method Based on Fixed-Gain Filter

• Published in: IEEE transactions on industrial electronics (1982) Vol. 65; no. 9; pp. 7119 - 7128
• Main Authors: Cai, Xinbo, Wang, Can, Kennel, Ralph
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2018; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Computer simulation; Covariance matrices; Electricity consumption; Energy sources; Feedback; Fixed-gain filter (FGF); Kalman filter (KF); Kalman filters; Parameters; Phase locked loops; Phase locked systems; phase-locked loop (PLL); Power system stability; Stability criteria; state estimation; Synchronism; Synchronization; Systems stability; three-phase grid; Tuning
• ISSN: 0278-0046; 1557-9948
• DOI: 10.1109/TIE.2018.2798600

As the demand for electricity is growing and the penetration of renewable energy resources is increasing, grid synchronization with high accuracy is essential for utility networks. This paper presents a novel fixed-gain filter (FGF) scheme with an optimal fixed feedback gain matrix to estimate the (angle) position and frequency of the grid, which ensures a fast and accurate synchronization under varying grid conditions. Instead of using the conventional phase-locked loop (PLL) scheme that suffers from the difficulty of parameter selection, the concept of the Kalman filter (KF) is synthesized to design the second-order FGF and third-order FGF for synchronization. To overcome the heavy computational processing for the KF, the feedback gain is subject to a single tunable parameter only, which can be calculated offline and refined within a certain small range fulfilling the system stability criterion. Compared with the PLL approach, the new FGF provides a faster and more precise tracking performance, an easier parameter tuning mechanism, a lower program complexity, and a better grid stability, which is verified by simulations and experiments in all cases.