增强双馈风电机组低电压故障穿越能力的多级控制策略

A Multi-stage Control Strategy for Enhancing Low-voltage Ride-through Capability of Doubly-fed Induction Generator Units

  • 摘要: 电网遭受大扰动导致电压骤降时,双馈感应风机需要配合硬件改造措施,以实现机组的低电压穿越。针对基于双馈风机的风电场在低电压故障穿越全过程需要协调功率控制策略来满足电网规范的问题,该文提出一种增强双馈风机低电压穿越能力和无功电流注入能力的多阶段控制策略。该策略包括3个阶段:电压跌落、暂态电压稳定和电压上升。电压跌落和暂态电压稳定阶段的策略负责改进低电压穿越控制,电压上升阶段的策略负责系统的恢复。该方法利用转子串阻抗保护电路和改进暂态电压控制完成低电压穿越。仿真结果表明,所提方法不仅能够有效抑制严重电压跌落故障下双馈风机所受到的暂态冲击,还能保证机组在故障期间提供无功功率,为电网电压提供支撑,提升机组故障运行能力。

     

    Abstract: When the grid experiences a major disturbance that results in a voltage drop, doubly-fed wind turbines need to coordinate with hardware-based modification measures to achieve low-voltage ride-through (LVRT) capability. To address the need for coordinated power control strategies throughout the entire LVRT process in DFIG-based wind farms to comply with grid codes, this paper proposes a multi-stage control strategy that enhances both the LVRT capability and reactive current injection capacity of DFIGs. This strategy includes three stages: voltage drop, transient voltage stability, and voltage swell. The voltage drop and transient voltage stability stages are responsible for the improved LVRT control, while the voltage swell stage ensures system recovery. This method utilizes the existing rotor string impedance protection circuit and improved transient voltage control to achieve LVRT. Simulation results demonstrate that the proposed approach not only effectively suppresses transient impacts on DFIGs under severe voltage sags but also ensures the injection of reactive power during faults, supports grid voltages, and enhances the fault ride-through capability of the units.

     

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