Physical regulation and dynamic characteristics of grid-tied photovoltaic systems with phase locking, nonlinear maximum power tracking, and disturbance-based islanding effect suppression

Grid-tied photovoltaic (PV) systems exhibit complex nonlinear photoelectric characteristics and electromagnetic dynamic behaviors, where phase synchronization, maximum power extraction, and islanding-induced electromagnetic distortion are core physical problems restricting system operation. In this work, we investigate the physical mechanisms behind phase deviation, power oscillation, and blind detection of the islanding effect in PV conversion systems and propose an integrated physical regulation strategy combining the dq-frame phase-locked loop (dq-PLL), adaptive nonlinear variable-step tracking, and variable-amplitude electromagnetic disturbance. Starting from the photoelectric transport mechanism of PV cells, we establish a single-diode physical model to describe the nonlinear P–V characteristics of PV arrays and derive the dq-axis electromagnetic decoupling model of grid-connected inverters to analyze the coupling effect of alternating electromagnetic quantities. The dq transformation-based phase locking method is adopted to study the phase dynamics of grid voltage, which realizes high-precision tracking of electromagnetic phase and frequency. A nonlinear tracking rule dependent on the gradient of P–V characteristic curves is constructed to suppress the intrinsic physical contradiction between transient dynamic response and steady-state power oscillation of PV systems. Furthermore, a variable-amplitude electromagnetic disturbance method is applied to regulate the electromagnetic parameters at the point of common coupling, which reduces the physical non-detection zone of the islanding effect and suppresses harmonic electromagnetic interference under normal operating states. A cooperative physical logic is designed to eliminate mutual coupling interference among phase dynamics, photoelectric power regulation, and electromagnetic disturbance modules. We verify the physical properties of the proposed strategy via numerical simulation and experimental measurement on a 5 kW PV platform. The results show that the maximum power tracking efficiency reaches above 99.2%, the total harmonic distortion of electromagnetic current is lower than 2.3%, and the islanding electromagnetic anomaly can be eliminated within 100 ms. This research reveals the coupling laws of photoelectric conversion and electromagnetic dynamics in PV systems and provides a physical optimization approach for the performance improvement of renewable energy conversion devices.