# Detection of Wind Turbine Failures through Cross-Information between Neighbouring Turbines
## 4 Results  
In this section, two signals from the gearbox subsystem are processed using the proposed method and all the data available in the database. These are the temperature signal \(w\)_rtm_avg_T_rm_P_Gbx and the pressure signal \(w\)_rtm_avg_Gbx_OilPress_ shown in the previous section. In Figure 11 the residuals obtained from \(w\)_rtm_avg_T_rm_P_Gbx in each of the five turbines are overlaid. In the upper plot, the raw residuals are shown, while in the lower plot they are shown after being filtered with a 50-sample moving average filter, which makes the interpretation easier. In Figure 12, the same representation is available for the residuals of the \(w\)_rtm_ signal. These two plots, due to the overlapping of the signals and the long time interval covered, are difficult to interpret but they allow us to notice the relative amplitudes and peaks that appear occasionally in the different turbines, and show that at some point these signals separate from the signal that was defined as a reference from the median. To improve the interpretation of these results, in the following figures we separate the information of these two graphs by turbines and compare them with the rotor speed, \(w\)_wgen_avg_RtrSpd_IGR_. Figures 13-17 show the information for turbines WT80, WT81, WT82, WT83, and WT84, respectively. For each of these plots, in the central part the signal \(w\)_wgen_avg_RtrSpd_IGR_ in the colour used to identify the turbine, is plotted. In the upper part, in black, the residue is coming from \(w\)_rtm_avg_Gbx_OilPress_, but it is reversed, so that the positive peaks of the Figure 12, in this representation, point downwards. The lower signal, also in black, represents the smoothed residual of the temperature signal, without any inversion. In the set of these five plots, the signals are scaled for a pleasing display, so their absolute amplitudes do not provide information. The information is in the position of the peaks of the residuals, their relative amplitude, and their position in relation to the sections where the turbine shows speed values of the \(w\)_wgen_avg_RtrSpd_IGR_ in the vicinity of zero. The rotor speed has the particularity that it allows to identify when a turbine is inactive while the rest of the turbines are working, which is indicative that the turbine is stopped, either in maintenance phase, or presumably out of order, and therefore in repair phase. In other words, when there is sufficient wind to move the set of turbines, the \(w\)_wgen_avg_RtrSpd_IGR_ signals of the turbines follow the operating pattern. However, if one WT is stopped, its \(w\)_wgen_avg_RtrSpdSpd_IGR_ is measured as zero, decoupling it from the general pattern. A detailed example can be seen in the last plot of Figure 1, where the signal \(w\)_wgen_avg_RtrSpd_IGR_ corresponding to the WT82 (in yellow), becomes zero when the rest of the signals of the same turbine (also in yellow) and represented in the upper plots, uncouple from the pattern. In Figures 13-17, the periods in which a turbine is stopped are represented in those intervals where the central signal is zero. The blue rectangles added in these figures (11 in total) highlight the time intervals where a peak in the residuals (black signals) is detected and the WT is stopped. The red rectangles (two in total, one in Figure 13 and one in Figure 17) show the presence of peaks in the residuals, but in this case the turbine is not stopped. In each of these plots there are blue rectangles that mark areas where there is a peak in some residue signal and capture a section where the rotor speed is zero and therefore the turbine is stopped. When that is the case, it can be noticed--but not always--that in both residues a peak is produced simultaneously. Note that there are few peaks of significant width that are not accompanied by the section, indicating that the turbine has stopped, although one can be found at the beginning of the Figure 17 corresponding to the WT84.