暂态同步稳定与故障冲击电流约束下构网型变流器自适应故障穿越控制方法

An Adaptive Fault Ride-Through Control Method for Grid-Forming Converters under Constraints of Transient Synchronous Stability and Fault Impulse Current

中文关键词:构网型变流器  故障穿越  暂态同步稳定性  冲击电流  虚拟阻抗比

keywords:grid-forming converter  fault ride-through  transient synchronous stability  impulse current  virtual impedance ratio

中文摘要:构网型（grid-forming，GFM）变流器可有效提升新型电力系统的稳定性，但其在故障穿越（fault ride-through，FRT）期间，仍面临器件过流与功角失稳的双重风险。为提升GFM变流器的暂态同步稳定性并有效限制故障冲击电流，开展了自适应故障穿越控制方法研究。首先，推导GFM变流器故障期间的功角变化曲线，基于等面积判据确定满足稳定约束的有功参考上限，并设计自适应有功参考值以增强故障时期的有功支撑能力；其次，采用旋转同步坐标系下的故障检测方法，推导冲击电流与虚拟阻抗比的解析关系，给出满足电流约束的阻抗比上限整定原则，确定最优阻抗比以提升同步稳定裕度，并据此构建自适应故障穿越控制方案；最后，通过电磁暂态仿真验证所提方案的有效性。仿真结果表明，该控制策略可有效限制故障冲击电流、减少功角偏移量，显著提高了GFM变流器的暂态同步稳定裕度。

Abstract:Grid-forming （GFM） converters can effectively improve the stability of new-type power systems， but they still face the dual risks of device overcurrent and power angle instability during fault ride-through （FRT）. To enhance the transient synchronous stability of GFM converters and effectively limit the fault impulse current， an adaptive FRT control method is studied in this paper. Firstly， the power angle variation curve of the GFM converter during a fault is derived. The upper limit of the active power reference meeting the stability constraint is determined based on the equal-area criterion， and an adaptive active power reference is designed to improve the active power support capability during faults. Secondly， a fault detection method based on the rotating synchronous reference frame is adopted to derive the analytical relationship between the impulse current and the virtual impedance ratio. The setting principle for the upper limit of the impedance ratio satisfying the current constraint is given， and the optimal impedance ratio is determined to improve the synchronous stability margin. On this basis， an adaptive FRT control scheme is constructed. Finally， the effectiveness of the proposed scheme is verified by electromagnetic transient simulations. The results show that the control strategy can effectively limit the fault impulse current， reduce the power angle deviation， and significantly improve the transient synchronous stability margin of the GFM converter.