# Clustering Analysis of Wind Turbine Alarm Sequences Based on Domain Knowledge-Fused Word2 vec
## 2 Alarm Data Description and Statistical Analysis  
### Alarm Data Description  
The alarm system of a wind turbine may vary depending on the manufacturer but generally possesses similar fundamental functionalities. It monitors the values of SCADA parameters, and when the monitored parameters exceed the predefined thresholds, relevant alarms are triggered. Similar to SCADA data, alarm data includes the status information of almost all key subcomponents of the wind turbine. The difference lies in the following aspects: SCADA data are recorded at regular intervals (typically every 10 min) as numerical data, covering both the healthy and faulty states of the wind turbine. In contrast, alarm data do not follow a fixed periodicity and consist of non-numerical records triggered and saved during abnormal conditions in the wind turbine. Hence, alarm data contain abundant fault information about wind turbines. By analyzing alarm data, it can be used for wind turbine fault diagnosis. Diagnosing wind turbine faults through alarms remains a challenge for on-site operators, which is primarily caused by the following three factors. First, alarms commonly include descriptive details concerning the wind turbine's anomalous condition. However, they may not directly specify the fault event's type. Second, alarm systems commonly exhibit redundant and unreasonable alarm configurations, resulting in false alarms, repeated alarms, and nuisance alarms [23]. In addition, when a fault occurs, a substantial quantity of alarms is activated within a short period. This surge of alarms can overwhelm the operator. The alarm data used in this paper are sourced from a wind farm situated in southern China. There are 24 wind turbines equipped with direct-drive, variable-speed, and variable-pitch generators. The provided alarm data cover the period from May 2016 to October 2017. Examples of several alarm records are shown in Table 1. The alarm records are organized chronologically, providing turbine number, triggering time, alarm type, alarm code, alarm flag, and description. Within this context, the alarm code assumes the role of a distinct identifier for each alarm occurrence. The alarm flag, on the other hand, designates the start or end of an alarm, thereby leading to the creation of two records for each alarm. Three categories of alarms exist: information alarms, warning alarms, and fault alarms. Information alarms primarily communicate changes in specific operational conditions. Warning alarms are initiated upon the approach of monitored variables to predefined thresholds, while fault alarms are activated upon the surpassing of these thresholds. When analyzing alarm data, our initial focus is on the numerical representations of individual alarms, such as A155 and T110 in Table 1. Subsequently, our focus shifts to alarm sequences. Due to the extensive interconnections among the mechanical structure, electrical connections, and complex control systems of wind turbines [24], the occurrence of a fault can trigger multiple alarms, forming an alarm sequence. For instance, [I2, A155, A155, T110] in Table 1 represents an alarm sequence. The alarms triggered by the same fault may vary under different operating conditions of the wind turbine [12]. However, these alarms exhibit a high level of similarity. Therefore, diagnosing wind turbine faults can be achieved by clustering alarm sequences triggered by the same type of fault. The alarm data of wind turbines are a manifestation of fault occurrences. Therefore, the labeling of an alarm sequence can be established based on the corresponding fault type. Maintenance records can provide the types of historical faults. However, owing to the self-diagnostic capabilities of wind turbines and inconsistent operational practices of personnel, a significant portion of faults lack corresponding maintenance records. This issue has been comprehensively addressed in the study by Ref. [20]. That is to say, a considerable