Performance Analysis of Three-Phase Phase-Locked Loops for Distorted and Unbalanced Grids

Abstract

This paper studies the performances of five typical Phase-locked Loops (PLLs) for distorted and unbalanced grid, which are the Decoupled Double Synchronous Reference Frame PLL (DDSRF-PLL), Double Second-Order Generalized Integrator PLL (DSOGI-PLL), Double Second-Order Generalized Integrator Frequency-Lock Loop (DSOGI-FLL), Double Inverse Park Transformation PLL (DIPT-PLL) and Complex Coefficient Filter based PLL (CCF-PLL). Firstly, the principles of each method are meticulously analyzed and their unified small-signal models are proposed to reveal their interior relations and design control parameters. Then the performances are compared by simulations and experiments to investigate their dynamic and steady-state performances under the conditions of a grid voltage with a negative sequence component, a voltage drop and a frequency step. Finally, the merits and drawbacks of each PLL are given. The compared results provide a guide for the application of current control, low voltage ride through (LVRT), and unintentional islanding detection.

Performance Improvement of Dual-Buck Inverter With Mitigating Reverse Recovery Characteristics and Supporting Reactive Power

“…As the penetration of the distributed generation (DG) into the distribution networks continues to increase, the DGs are required to participate in the grid stability control [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. One of the requirements is the low voltage ride through [1][2][3][4][5].…”

“…As the penetration of the distributed generation (DG) into the distribution networks continues to increase, the DGs are required to participate in the grid stability control [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. One of the requirements is the low voltage ride through [1][2][3][4][5]. In case of a grid fault, the DGs should be connected to the grid for the specified voltage and time, and then inject the reactive power to support the grid.…”