针对一水轮发电机单机模型进水闸门位置故障，用对等空间法检测了未知输入干扰条件下的系统故障，为了减少计算量，提高计算速度，采用窗口平移的残差计算方法。结果表明这种计算方法十分有效，残差对故障非常敏感，而对噪声具有很强的鲁棒性。与文献［４］辨识法给出的结果比较，对等空间法的残差对故障的响应具有持续性，而不是瞬态性，有利于准确检测故障，降低故障误报率。 Aiming at the fault location of intake gate of single hydro generator model, the system fault is detected by the method of equal space method with unknown input interference. In order to reduce the computation and improve the calculation speed, residual error of window translation is adopted. The results show that this method is very effective, the residuals are very sensitive to faults and robust to noise. Compared with the results given in the literature [4], the residuals of the equivalence space method are persistent rather than transient, which helps to detect the fault accurately and reduce the false alarm rate.