电网短路时并网双馈风电机组的特性研究

Characteristics of DFIG-based Wind Generation Under Grid Short Circuit

双馈感应风力发电机组(doubly fed induction generator,DFIG)对电网扰动十分灵敏,在电网发生故障期间双馈风电机组与电网的相互影响会造成电网暂态特性以及短路电流分布的显著变化。但是由于双馈感应发电机组与同步发电机组的结构及运行原理均不相同,且目前对其故障过程的研究也比较有限,使得并网双馈风电机组的故障特性还不甚清晰。在以双馈风电机组为主的风电大规模并网背景下,电网的安全稳定运行面临着严峻的挑战。从双馈风电机组的控制策略对其故障特性的影响机制出发,对双馈风电机组在电网发生对称以及不对称短路情况下的短路过程进行深入分析,并进一步推导了适用于不同电网短路情况的并网双馈风电机组短路电流表达式,仿真和算例结果验证了该表达式的正确性。

Doubly fed induction generators （DFIGs） are very sensitive to the disturbances of grid, so the transient characteristics and short-circuit current of grid will be dramatically changed by the interaction between the generation and grid under fault condition. However, the fault characteristics of the DFIG is not clear, because the structure and operating principle is very different from that of the traditional synchronous generator, and the researches about its fault behavior is relatively limited. In the background of the interconnection of large-scale wind generation, the security and stability of whole power system will be challenged. In this paper, the influencing mechanism of the control system on short-circuit behavior was firstly discussed. Then the short-circuit behavior under symmetrical and asymmetrical short circuit were further researched. Finally, the expressions of short circuit current for DFIG under different fault conditions were proposed. The effectiveness of the expression was proved by simulation and calculation example.