# Detection of Wind Turbine Failures through Cross-Information between Neighbouring Turbines
## 3 Materials and Methods
### Experimental SCADA Data  
A comprehensive three-year SCADA database of five wind turbines of 2.5 MW Fuhrlaender, model FL2500, is presented. This turbine model consist of 10 different systems: grid, transmission, generator, converter, nacelle, hydraulic system, rotor, meteorological, turbine, and tower. The turbine signals are also organised into 10 groups, according to the system they belong to. The data in this database were generated by the wind turbine SCADA and collected via an open communication platform (OPC) according to IEC 61400-25 format, which is the standard protocol used for communication between wind turbines and SCADA systems. Events and statistical indicators are recorded every five minutes. The values reported for each sensor are: Minimum, Maximum, Mean, and Standard Deviation. The database contains 312 analogue variables from 78 different sensors. The variables are stored with a name symbolising the (sub)system and the type of variable, separated by an underscore; the first term is the main physical system, e.g., generator = wgen, gearbox = wtrm, nacelle = wmac, etc. The second term is the type of variable of the 5-min interval, e.g., min = minimum, avg = average, etc. The third and fourth terms are the final name of the variable. Each of the events is labelled with a number. If the WT operates normally, the label is '0'. If there is a warning, the turbine is not stopped and the label is '1'. Finally, an alarm is indicated using '2' as label, and in that case the WT is stopped. Alarms occur very sporadically in WT, as the turbine operates correctly most of the time. Therefore, it is common practice to combine warnings and alarms into a single class because a warning can precede a future alarm if the WT is not properly inspected. This reduces the problem to a two-class scenario. The aim is to identify in advance when a wind turbine starts operating with potential problems that could lead to a warning or alarm condition. In the experiments, only some of the system-related variables of the analysed subsystem are used. The database was provided by Smartive ([[http://smartive.eu](http://smartive.eu)]([http://smartive.eu](http://smartive.eu))) (accessed on 20 April 2022) and has been used in other publications [4; 21; 22; 23; 24]. All the data from the SCADA system is in a MySQL database, and the MATLAB Database Toolbox was used to download data from it (see Table 1 for the exact dates of the data acquisition). So, all the processing has been done under a MATLAB 2021b environment running on a 2.4 GHz Intel Core i9 of 8 cores with 64 GB 2667 MHz DDR4 in macOS Monterrey. In this contribution, signals from two different turbine systems, generation and transmission, are used. To show in context where each of the signals used belong and why they were chosen, two tables (Tables 2 and 3) are organised. First, to show the synchronous variation of the signals in Section 2 and to introduce the method, (outliers filtering, pattern generation, etc.) in Sections 3.1-3.4, four signals from the generator system are used (see Table 2). This is a selection of three slowly varying temperature signals and one more quickly varying angular velocity signal that are used to determine the status of the WT. \begin{table}
\begin{tabular}{l c c} \hline \hline  & **WT Id** & **5 min** \\ \hline  & 80 & 01-Jan-2012 01:00 \\  & 81 & 01-Jan-2012 01:00 \\ start & 82 & 01-Jan-2012 01:00 \\  & 83 & 01-Jan-2012 01:00 \\ \hline  & 80 & 08-Dec-2014 06:00 \\  & 81 & 08-Dec-2014 06:00 \\ end & 82 & 08-Dec-2014 06:00 \\  & 83 & 08-Dec-2014 06:00 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Temporal distribution of data and turbine identifier. Second, two signals from the gearbox subsystem are used. The gearbox is a subsystem within the transmission system. Since a fault in the gearbox is expensive and difficult to repair, it is one of the subsystems that requires the most monitoring. Therefore, in this work, the gearbox subsystem is the one chosen to be monitored.