With the development of the variable-frequency AC power generation system of More Electric Aircraft （MEA）， the increase of nonlinear power conversion devices and constant power electromechanical loads in the MEA variable-frequency AC power grid has led to problems in the aircraft power system. Therefore， it is necessary to extract the fundamental synchronous signal of the power supply quickly and accurately to monitor the operating status and provide conditions for the application of power quality control devices. To address the above issue， this paper constructs a Phase-Locked Loop （PLL） structure with strong harmonic suppression and frequency adaptation capabilities based on the General Delayed Signal Superposition （GDSS） operator and frequency adaptive feedback loop design. The GDSS operator， having strong harmonic elimination ability and rapid dynamic response speed， is utilized to achieve fast synchronization of the fundamental wave signal of the MEA variable frequency power grid voltage in various environments. The frequency feedback outer loop is employed to enhance its adaptive ability to track frequency in real-time in complex variable frequency power grid environments. Finally， the proposed method is compared with traditional synchronization algorithms commonly used in MEA variable frequency power grids through experiments. The results show that the method proposed has the advantages of fast dynamic response， good frequency selection and strong robustness， and can achieve fast and accurate extraction of synchronization signals from MEA variable frequency AC power grids under various operating conditions.