大型发电机组等效故障次数的分析与计算

大型发电机组在运行过程中存在大量的强迫降出力(IUD)事件。在利用随机过程模型分析大型发电机组的可靠性指标时，若将一次IUD事件计为1次故障。则对机组的可靠性水平估计偏低；若忽略IUD的影响，不计入故障，又使机组的可靠性估计偏高。文中针对这种情况，引入“分数次故障”的概念，将IUD等效为分数次故障，用分数次故障的大小来反映IUD的故障严重程度，从而使发电机组的可靠性评估更接近实际情况。此外，现有的随机过程模型都是基于整数次故障的，为便于利用这些模型，文中还介绍了将分数次故障进行整数化的方法。最后用实例简要说明了应用上述方法处理某地区一台300MW发电机组原始数据，并获得有效故障数据的情况。

ANALYSIS AND CALCULATION OF EQUIVALENT FAILURE NUMBER OF LARGE GENERATING UNITS

In-service unplanned derated (IUD) events frequently occur during the operating period of large generating units. When analyzing the reliability of the units by adopting a stochastic process model, the reliability level of units will be underestimated if one IUD event is regarded as one failure; to the contrary, the reliability level will be overestimated if IUD events are neglected. Therefore, a new concept of fractional failure is presented in this paper to represent the effect of IUD events. According to this concept, any IUD event is equivalent to a fractional failure, the value of which represents the degree of failures of large generating units. Moreover, a method with which the fractional failures are transformed to integer failures is proposed because the existing stochastic process models are all based on the integer failures. Finally, the original data from a300 MW generating unit isprocessed and the effective failure data are obtained with this method.