DFIG短路热效应对故障参数灵敏度的解析表达

Analytical expression of parametric sensitivity of thermal effect of DFIG during short-circuit

定子外侧三相短路后温升,可能损坏双馈感应发电机(doubly-fed induction generator,DFIG)。采用逐步积分方法,可以量化短路热效应,但无法区分周期与非周期分量,不易判断敏感因素,计算量也较大。文章对DFIG短路电流平方求积分,建立热效应解析表达;通过分解热效应,提出周期与非周期分量的解析表达;分析各分量衰减特性和影响因素,建立热效应实用表达形式;提出热效应对定子电压降和撬棒电阻的灵敏度。所提模型有助于估计DFIG短路热效应,判断相关影响因素,为风电场热稳定检验提供计算工具。

The temperature rise after three-phase short-circuit current at the stator may damage the doubly-fed induction generator(DFIG).The thermal effect due to the short-circuit may be quantified by the step-by-step integration,but the periodic and aperiodic components cannot be differentiated,and it is difficult to decide the sensitive factors,and the calculation effort is large.In this paper,the square of the short-circuit current of the DFIG is integrated to derive the analytical expression of the thermal effect.By decomposing the thermal effect,the analytical expressions of the periodic and aperiodic components are proposed.By analyzing the decaying and relative factors,the practical expression of the thermal effect is derived.The analytical expressions of the sensitivities of the thermal effect to the stator voltage drop and the crowbar resistance are proposed.The proposed model helps to estimate the thermal effect of the DFIG after short-circuit,and judge the relative factors,which provides the calculation tool for the thermal stability verification of the wind farms.