Method for triggering fault diagnosis at low-pressure alarming state of deaerator

The invention relates to a method for triggering a fault diagnosis at a low-pressure alarming state of a deaerator. The method comprises the following steps: when actually-measured pressure of the deaerator is lower than a low limiting value after the pre-treatment, activating to trigger the fault diagnosis; firstly carrying out the diagnosis on an admission interrupting fault according to a fault priority; if a diagnosis result is tenable, turning to an admission interrupting diagnosis result human-computer interface for explaining that the admission interrupting fault is tenable as well as the confidence coefficient of the admission interrupting fault, reasons for causing the admission interrupting fault and operation guide information, and then finishing a whole diagnosis process; if the diagnosis result is not tenable, turning to a diagnosis for low pressure of a four-section steam extraction deaerator, a deaerator safety valve wrongly-opened diagnosis, a deaerator drain valve fully-opened diagnosis and a deaerator water-level adjusting valve failure ineffectively-opened diagnosis; and finally, carrying out a diagnosis on the valve full opening of the deaerator water-level adjusting valve. The method provided by the invention can be used for carrying out the real-time fault diagnosis on heat returning system equipment and operation conditions and the operation safety of the deaerator and a boiler water feed pump steam turbine are improved.