# Wind Turbine Predictive Fault Diagnostics Based on a Novel Long Short-Term Memory Model
## 2 SCADA Data
### Operational Data and Status Data  
The collected SCADA operational data include alarm data, control information, electrical signals, pressure data, temperature data, turbine data, miscellaneous signals, and other signals. The SCADA system operates at a 10 min sampling rate by monitoring instantaneous parameters, such as wind speed, pitch angle, rotor speed, yaw error, electrical power, currents, voltages, temperatures, and pressures. Taking Table 1 as an example, the minimum, maximum, mean, standard deviation, and ending values of wind speed are collected with the corresponding timestamps. The original dataset includes more than 2000 features and approximately 70,000 data points with regard to the 17 months to be studied. The information about requested shutdowns, faults, or warning events is provided by status data. As seen in Table 2, fault and warning events are tracked with respect to their corresponding event codes, on-times, and off-times. There are miscellaneous operating states under the abnormal or faulty conditions of the WT. According to [PERSON] and [PERSON] (2017), the status of fault data is assigned as follows:  
\[ \begin{split}& If\ T_{SCADA}(t)<T_{fault}<T_{SCADA}(t+1),\ then\\ & Event.Code(t)=Event.Code(t+1)=Event.Code\Big{(}T_{fault}\Big{)}\end{split}  \tag{1}\]  
where \(T_{SCADA}(t+1)\) denotes the one-step behind (or 10 min behind) SCADA data since both timestamps, \(t\), and \(t+1\), have 10 min intervals. \begin{table}
\begin{tabular}{l l l l l} \hline \hline
**StartTime** & **WindSpeed** & **WindSpeed** & **WindSpeed** & **WindSpeed** & **WindSpeed** \\  & **\_mps\_Min** & **\_mps\_Max** & **\_mps\_Mean** & **\_mps\_Stdev** & **\_mps\_EndVal** \\ \hline
21/05/2018 22:00:00 & 3.577394 & 10.11077 & 6.8690084 & 1.3447459 & 5.802108 \\
21/05/2018 22:10:00 & 3.062414 & 10.03982 & 6.7177955 & 1.108204 & 6.073331 \\
21/05/2018 22:20:00 & 4.69204 & 9.636992 & 7.1981784 & 1.0209401 & 8.475427 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Ten-minute SCADA operational data. Figure 1: Levenmouth offshore wind turbine ([PERSON], 2017). The 10 min period is applied to capture any fault occurrences. For example, in Table 2, the operational period from \"21/05/2018 20:20:00\" to \"21/05/2018 20:30:00\" should be labelled as \"Gearbox Cooling Line Pressure Too Low\" with its event code of 543 due to its fault occurrence within the 10 min time band. As seen in Figure 2, the frequency of occurrences of each status varies. Any event code above zero indicates an abnormality. The majority are fault event codes only occurring a few times, but the faults under the event codes 399, 435, 570, and 1219 have occurred more than 800 times within this period. Some event codes, such as 12 and 97, denoting SCADA shutdown request and yaw error, respectively, are not associated with a defined fault status despite their appearances being 932 and 1290, respectively. Aside from these two examples, the majority of event codes are merely warnings, irrelevant to faults, so many event codes are of minor interest in this paper. Additionally, the event codes relating to downtime due to maintenance actions, noise curtailments, and requested owner stops in Figure 2 are to be excluded. By excluding the data related to downtimes and faults with very limited frequency, only a small number of faults can be reserved according to their relatively frequent occurrences, as seen in Table 3. \"HPU 2 Pump Active For Too Long\" relates to a fault that occurred in the hydraulic pump unit (HPU), while \"PcsOff\" and \"PcsTrip\" relate to shut-off faults and circuit trips within the power conditioning system (PCS), respectively. The deep-learning model must train the classifiers for the specific fault instances defined in Table 3. Hence, the reserved SCADA data can be classified into nine categories: (1) fault-free; (2) HPU 2 pump active fault; (3) Blade 3 slow response; (4) pitch system fatal fault; (5) gearbox cooling pressure fault; (6) (Demoted) gearbox pressure 2 fault; (7) PcsOff fault; (8) PcsTrip fault; (9) sub-pitch fatal fault.