双馈风电机组HVRT暂态电流计算及其控制策略研究

Study on HVRT transient current calculation and control strategy of doubly-fed induction generator

文章从双馈风力发电机组(DFIG)暂态过程出发,考虑高电压穿越(HVRT)过程中切换延时和无功控制因素的影响,推导了DFIG对称电压骤升下优化后转子全电流的表达式,弥补了现有暂态过程计算中准确度不足等缺陷。利用优化后转子全电流表达式,设计了一种有效抑制转子过流的限流控制策略,显著提高了风电并网稳定性。仿真验证了转子电流表达式的正确性和改进控制策略的有效性。

With the continuous growth of installed capacity of wind power in China,the accurate calculation of rotor current of doubly fed wind turbines under voltage fault becomes more and more important,which is related to the design and performance of voltage ride-through control strategy.Current analysis of doubly-fed wind turbines during voltage surge has been studied,but the switching of operation state during high voltage ride-through has not been taken into account,which leads to errors in calculation of rotor current variation.Therefore,starting from the transient process of DFIG,considering the influence of switching delay and reactive power control factors in the process of high voltage traverse(HVRT),the expression of the optimized rotor current under the symmetrical voltage surge of DFIG is deduced,which makes up for the deficiency of accuracy in the calculation of current transient process.Based on the optimized rotor current expression,a current limiting control strategy is designed to effectively suppress the rotor overcurrent,which significantly improves the grid-connected stability of wind power.The simulation results verify the correctness of the rotor current expression and the effectiveness of the improved control strategy.