双馈感应发电机暂态特性分析及Crowbar阻值优化

发布时间：2019-03-03 19:54

【摘要】：双馈感应发电机(DFIG)的暂态过程是研究其低电压穿越(LVRT)的基础和关键。常规研究大多只针对故障发生期间的电磁暂态过程,而未涉及故障清除这一过程,对DFIG的暂态过程分析不全面,导致对转子最大短路电流计算不准确,进而导致Crowbar阻值选取不合理。本文从DFIG数学模型出发,给出了电网电压对称跌落及电网电压恢复时的定子磁链暂态表达式,以转子侧等效电路为基础分析推导转子电流的解析表达式,并据此修正了Crowbar阻值。在PSCAD/EMTDC中建立1.5MW并网DFIG仿真模型,验证了理论分析推导的正确性;并揭示不同故障持续时间将导致电网电压恢复时DFIG不同的暂态过程,忽略故障清除时刻的暂态过程将导致Crowbar阻值选取过大,Crowbar阻值选取需同时考虑故障发生和清除时刻的暂态过程。
[Abstract]:The transient process of doubly fed induction generator (DFIG) is the foundation and key to study its low voltage traversal (LVRT). Most of the conventional studies only focus on the electromagnetic transient process during the fault occurrence, but not the fault clearing process. The analysis of the transient process of the DFIG is not comprehensive, which leads to the inaccurate calculation of the maximum short circuit current of the rotor. This leads to unreasonable selection of Crowbar resistance value. Based on the mathematical model of DFIG, this paper gives the transient expression of stator flux when the voltage of power network is symmetrical sag and the recovery of power network voltage. Based on the equivalent circuit of rotor side, the analytical expression of rotor current is deduced, and the Crowbar resistance value is modified accordingly. The simulation model of 1.5MW grid-connected DFIG is established in PSCAD/EMTDC, and the correctness of the theoretical analysis and derivation is verified. It is revealed that different fault duration will lead to different transient processes of DFIG in power network voltage recovery, and neglecting the transient process of fault clearing time will lead to excessive selection of Crowbar resistance values. The transient process of fault occurrence and clearance time should be taken into account in the selection of Crowbar resistance value.
【作者单位】：华北电力大学电气与电子工程学院;
【分类号】：TM315

【相似文献】