并网光伏系统性能提升：应对非线性负载挑战

Photovoltaic (PV)-based consumer-end power generation supports sustainable development and is typically grid-connected to minimize dependence on bulky energy storage systems. However, modern power electronics-based local loads significantly degrade system performance, especially under weak grid conditions. Conventional control methods struggle to maintain grid current quality during disturbances on the grid, PV, or load side, and often lack the required dynamic responsiveness. This paper proposes a fast and robust grid integration control strategy for injecting PV array power into the grid while enhancing grid current quality in the presence of both load-side and grid-side disturbances. The proposed method utilizes a dual second-order generalized integrator (SOGI) to synthesize balanced, steady, and sinusoidal three-phase reference grid currents-even under distorted grid conditions-while inherently rejecting measured voltage's harmonics, imbalance and DC offsets. This eliminates the need for additional integrals or complex feedback loops, thereby overcoming the limitations of conventional SOGI-based methods. Furthermore, a least mean square (LMS)-based algorithm is employed to extract the active power component of the load current, enabling auxiliary active power support via a PI controller and enhancing the system's dynamic response to load variations. The proposed strategy is implemented in a weak-grid-connected PV system supplying nonlinear battery charging loads without dedicated harmonic compensation hardware, and its superior performance is validated through experimental results on a laboratory prototype.