不同故障状态下电网形成变换器的故障穿越控制

Fault Ride-through Control of Grid-forming Converter in Different Fault States

电网形成GFM(grid-forming converter)变换器作为高渗透率电力电子设备电力系统的主要元件之一,其故障穿越FRT(fault-ridethrough)能力是保证高度电力电子化电力系统稳定运行的重要基础。基于此,提出1种适用于GFM变换器的FRT策略,既考虑了变换器的硬件约束(即电流约束),又可在发生对称和非对称故障时使GFM在保护模式下运行。首先,详细分析了GFM变换器的FRT相关问题;然后,建立了1种适当的FRT模型及控制方法;最后,通过功率硬件在环仿真与实验验证所提方法的有效性。结果表明,与电网跟随变换器相比,所提控制方法可保障GFM变换器在故障时瞬时注入无功电流,以防止变换器出现过流问题,并最终实现GFM变换器在严重故障条件下仍可容错运行。

The grid-forming( GFM) converter is one of the main components of high-permeability power electronic equipment,and its fault ride-through( FRT) capability is an important basis for ensuring the stable operation of a power system with a high degree of power electronics.On this basis,an FRT strategy for GFM converter is proposed,which not only considers the hardware constraints( i.e.,current constraints) of the converter,but also can keep it running in protected mode under symmetric and asymmetric faults.First,the FRT-related problem of the GFM converter is analyzed in detail.Then,an appropriate FRT model and the corresponding control method are established.Finally,the effectiveness of the proposed method was verified by power-hardware-in-the-loop simulation and experiment.Results show that compared with a grid-following converter,the proposed control method can guarantee the instantaneous injection of reactive current when the GFM converter fails to prevent the overcurrent problem,and the GFM converter can still operate fault-tolerant under serious fault conditions.