Adaptive Symmetrical PLL Based Impedance Shaping and Modelling Method to Improve Stability in Weak Grid

This paper introduces an Adaptive Symmetrical Phase-Locked Loop (AS-PLL) designed to address various issues associated with traditional PLLs. An improved PLL architecture has been developed, the new PLL topologie allows to reduce frequency coupling and prevents unwanted sub-synchronous resonance oscillation resulting from classical asymmetry PLL. The system stability has been by integrating a structure and model into the PLL. Additionally, the impedance shaping method is used, with the assistance of the impedance model, to design state feedback loops that offer flexibility in bandwidth for the PLL. This was done while considering the current/power control loops to stabilise the system in the presence of a weak grid, The simulation results clearly illustrate the accuracy and effectiveness of the proposed strategy.