Voltage Source Converters (VSCs) connected to weak grids may face difficulties in synchronization leading to their instability. As the heart of the system, Phase Locked Loop (PLL) is responsible for synchronism of VSCs. In this paper, using the nonlinear state space model of the system composed of the grid and the PLL, stability and domain of attraction of the equilibrium point of the system is investigated. Afterwards, using Lyapunov theorem, a nonlinear controller that extends the domain of attraction of the equilibrium point is designed. Using phase portraits, the stability of the system with and without the designed controller while the VSC is connected to a very weak grid is evaluated. The results confirm that the system with the proposed controller remains stable, whereas the conventional system cannot maintain stability. Additionally, the domain of attraction of the compensated system is calculated. Finally, the results from phase portraits are validated by simulating the grid-connected VSC.
Stability Analysis and Nonlinear Control of Phase Locked Loop of a Weak-grid Connected Voltage Source Converter
2020-09-10
3124270 byte
Conference paper
Electronic Resource
English
BASE | 2016
|Phase‐Locked Loop Using Complex‐Coefficient Filters for Grid‐Connected Inverter
Online Contents | 2014
|Voltage reconstruction method based on phase-locked loop
European Patent Office | 2015
|