An Adaptive Enhanced Complex-Coefficient Filter-Based PLL in Variable Frequency Grid

The complex-coefficient filter-based phase-locked loop (CCF-PLL) is widely used in state estimation for the constant frequency grid system. However, its performance under power systems with a variable frequency is generally unacceptable and related applications are consequently rare. This letter proposes an adaptive enhanced complex-coefficient filter-based phase-locked loop (AECCF-PLL) that accurately estimates the operational state of variable frequency grids. By deriving the relationship between model parameters and frequency, a frequency adaptive module is established to dynamically correct the model parameters in real-time. Furthermore, a stability analysis of the system is provided to meet the requirements of stability and fast response for state estimation in more electric aircraft (MEA) variable frequency grids and the computational workload is relatively small. Experimental tests show strong evidence for the effectiveness and validity of the proposed AECCF-PLL method