基于DBR的双馈风力机组低电压穿越方案设计

讨论了电网电压跌落下当前双馈风力发电机组各种LVRT技术拓扑方案及控制策略的优缺点，提出一种不同于常用Crowbar技术的低电压穿越技术方案。在基于DBR（Dynamic Brake Resistance）双馈风电机组新型LVRT拓扑结构及功能分析基础上，建立双馈风电机组在电网正常运行和发生低电压故障情况下发电系统的数学模型进行理论分析，提出了风电机组发生LVRT的控制策略。最后在此技术方案下进行20%电网故障下LVRT试验，试验实验数据充分证实了技术方案的正确性。

Design for the LVRT scheme of DFIG based on DBR

Advantages and disadvantages of all kinds of LVRT topological structures and the control strategies applied in the current DFIG are discussed, and the new LVRT scheme different from the Crowbar technology is presented. On the basis of analyzing the new LVRT topological structures of DFIG with DBR circuit topology as well as the effect of the DBR circuit during grid voltage dip, the mathematical models of the equivalent circuit of DFIG power system during normal voltage and grid voltage dip are established. Through analyzing the mathematical models, the control mode of LVRT is presented. At last, the experimental waveforms are analyzed at the WEC rate power output while under 20% balanced and unbalanced voltage dip respectively on the new LVRT topology, and it is fully verified that the DBR strategy is feasible.