Photovoltaic power plant string anomaly alarming method and alarming device

The invention provides a photovoltaic power plant string anomaly alarming method, which comprises the following steps: A, the historical data of each combiner box in a point station are extracted, thecurrent values of all strings in the combiner box are subjected to abnormal state judgment, and a state matrix for all strings is saved; B, the abnormal current values in the state matrix are extracted, periodic analysis is carried out, shadow occlusions are classified and marked according to a periodic analysis result, and based on the marked result, a device image is completed; and C, whether current of all strings under each combiner box is abnormal is judged in real time, if current of a certain path of string is abnormal, the device image of the string in the combiner box is extracted, and based on the comparison result between the abnormal moment and the device image, whether to be reported as a fault is judged. On the basis of automatically judging the fault state of each string, aperiodic abnormal fluctua