构网型逆变器自适应低电压穿越控制策略OA

Grid-forming(GFM)inverters are prone to transient angle instability and overcurrent under grid voltage sag conditions.Based on the virtual synchronous generator(VSG)control principle,this paper proposes a low voltage ride through(LVRT)control strategy integrating adaptive power regulation and hierarchical current limiting.First,a phasor diagram method and an analytical fault current model are adopted to analyze the mechanisms underlying transient power angle instability and overcurrent of VSG-controlled GFM inverters during grid voltage sags.On this basis,a power angle compensation factor is set in the active power-frequency control loop,which adaptively adjusts the active power reference value according to the depth of grid voltage sag to achieve stable control of the power angle.Meanwhile,point of common coupling(PCC)voltage feedforward is incorporated into the reactive power-voltage loop to dynamically regulate the reactive voltage reference.A current-limiting mechanism is incorporated into both the voltage and current double closed-loops to suppress fault currents.Simulation results show under moderate and severe voltage sag conditions,the proposed control strategy constrains transient power angle fluctuations within±0.4 rad and maintains both transient surge current and steady-state current within safe thresholds,exhibiting superior performances.