风机故障后有功控制对系统暂态功角失稳的影响机理（英文）

Impacts of Post-fault Active Power Controls of DFIGs on Rotor Angle Instability

规模持续增长的并网双馈风电场使暂态功角失稳现象变得更加复杂。提出了双馈风机故障后有功控制对系统暂态功角失稳的影响机理。为了维持系统故障后稳态,双馈风机故障后有功功率被要求从故障下的低水平值逐渐恢复至故障前水平值或其附近。据此,首先揭示双馈风机有功恢复控制对系统暂态功角各摆次失稳的影响。研究表明,双馈风机有功恢复控制加剧了首摆与奇数多摆的失稳可能性,同时削弱了偶数多摆的失稳可能性。通过考虑各摆次相互关系与被影响程度,进一步分析双馈风机有功恢复速率对系统暂态功角失稳的影响,并提出相应的暂态功角失稳模式。当大规模双馈风电场有功恢复速率因不同控制策略被设置为从快到慢等不同速率值时(假设在每种控制策略下恢复速率恒定),在相应顺序场景下,系统会出现3种失稳模式(其临界失稳分别为首摆失稳、奇数多摆失稳以及第2摆失稳)。最后对所提出机理进行仿真验证。

With increasing integration of wind farms utilizing doubly-fed induction generators(DFIGs) into power systems, rotor angle instability phenomena become more complicated. This paper proposes a novel impact mechanism of post-fault active power controls of DFIGs on rotor angle instability. As DFIG post-fault active power generally restores from during-fault level to pre-fault level or nearby to maintain post-fault steady state, impacts of DFIG active power recovery control on rotor angle instability are presented. It indicates that the recovery control increases possibility of the 1st swing instability and odd multi-swing instability and decreases possibility of even multi-swing instability. Then, impacts of DFIG active power recovery controls with different recovery rates on rotor angle instability are put forward, considering the impact degree on each swing instability and relation of all swings. As the recovery rate(assumed to be consent in each control strategy) of a large amount of DFIGs is set from fast to slow due to different control strategies, three instability modes will be formed. Their critical instabilities are the 1st swing instability, odd multi-swing instability, and the 2nd swing instability, respectively. Simulation results validate effectiveness of the proposed mechanism.