不平衡电压下双馈异步风力发电系统的建模与控制

提出了不平衡电网电压条件下双馈异步发电机(DFIG)在正、反转同步速旋转坐标系中的完整数学模型,推导和分析了不平衡电网电压条件下DFIG定子输出瞬时有功、无功功率组成.在此基础上,提出了小值稳态不平衡电网电压条件下增强DFIG不间断运行能力的4种可供选择的控制方案.讨论了不同不平衡控制目标下转子正、负序电流指令值计算原则,设计了正、反转同步速旋转坐标系中DFIG的双幽转子电流控制器的不平衡控制方案,实现了不平衡电网电压条件下转子正、负序电流的独立跟踪控制,有效地提高了小值稳态不平衡电网条件下风电机组的不间断运行能力.仿真研究验证了理论分析的正确性和所提出的双dq转子电流不平衡控制方案的有效性.

Modeling and Control of the DFIG Based Wind-power Generation System Under Unbalanced Grid Voltage Conditions

This paper proposes a novel unified mathematical model for the doubly-fed induction generator (DFIG) in the positive- and negative- synchronously rotating frames under generalized unbalanced grid-voltage conditions while deducing and analyzing in detail the stator output instantaneous active- and reactive-power of the DFIG under unbalanced grid-voltage conditions. On the basis of the model developed, the paper presents four kinds of selectable unbalanced control schemes for the purpose of enhancing the fault ride-through (FRT) capability of the DFIG wind power generation system under unbalanced grid-voltage conditions. The design principles of calculating the positive- and negative-sequence rotor current references for the four kinds of selectable unbalanced control schemes are thoroughly discussed. Meanwhile, the unbalanced control strategies based on dual-dq rotor current regulators are presented in the positive- and negative- synchronously rotating frames, which makes the positive- and negative- components of rotor current regulated independently and, as a result, the FRT capability of DFIG under small steady-state unbalanced grid-voltage conditions is capable of effective improvement. The correctness of the theoretical analysis and the feasibility of the unbalanced control scheme with the dual-dq rotor current regulators employed are validated by detailed simulation studies.