Decoupling Strategy for Three-phase Photovoltaic Grid-connected Inverters Based on Double Closed-loop Strategy

With the increasing penetration of distributed photovoltaic (PV) systems, grid-connected PV inverters must achieve rapid, accurate, and lowharmonic power injection across a wide operating range.Conventional control methods in the abc stationary reference frame exhibit significant steady-state errors and severe AC coupling effects, failing to meet high power quality requirements.To address the power tracking accuracy and dynamic response challenges in three-phase PV inverters, this paper proposes a dual-loop control strategy implemented in the dq rotating reference frame, consisting of an outer power loop and an inner current loop.By converting AC quantities into DC components through dq transformation, and incorporating grid voltage feedforward and feed-forward decoupling compensation, independent active/reactive power control is achieved.Simulation results demonstrate rapid power response without steady-state error during dynamic processes-where active power (P) increases from 2.5 kW to 5 kW at 0.1 s and reactive power (Q) rises from 0 kVA to 3 kVA at 0.2 s, verifying the effectiveness and stability of the proposed control strategy.