双馈电机的Crowbar参数整定及保护特性研究

Study on Crowbar parameter tuning and protection features of doubly fed induction generator

为了防止变速恒频双馈风力发电机短路电流对转子侧变换器造成损坏,常采用Crowbar保护电路。建立风力发电机短路电磁过渡过程的数学模型,通过对数学模型进行拉普拉斯变换及其反变换,求取短路电流的表达式,并求出最不利的情况下电流的最大值,在该值下对Crowbar电路的参数进行整定及保护。为了验证所整定的Crowbar电阻的精确性,分别以3 MW,2.75 MW,660 kW发电机为例进行分析,仿真结果表明,在该数学模型下,所整定的电阻提高了对Crowbar电路的旁路电阻整定的准确性,不仅能对转子侧变换器进行保护,同时也能对发电机和机械结构起到保护作用。

In order to prevent the converter damage on the rotor side caused by the short circuit current, the crowbar protection circuit is installed in the VSCF doubly fed wind power generator. The corresponding mathematical model of the short-circuit fault in the electromagnetic transient process is established.Through laplace transformation and its inverse-transformation to deduce the analytic expression of the short-circuit current. The resistance value of the crowbar protection is tuned and analyzed under the maximum circuit values in the worst situation. In order to show the accuracy of the tuning resistance, take three power types, which are 3 MW, 2.75 MW,660 kW, as example to analyze. The simulation results show that the proposed analytical method could increase the tuning accuracy of shunt resistance in crowbar circuit, thus the crowbar circuit could not only protect the rotor side converter, but also has the protection function on the generator and mechanical structure.