## 4 On-Site Micro-Grid Measurements and Trigger Parameter Selection  
The High Frequency digitiser system was installed in Malaga in October 2022. As indicated above, the system's objective is to acquire signals with a high sampling frequency in an unattended manner to cover a wide variety of PQ events. For this reason, the configurable time window width of the triggers based on DC signals was chosen on significantly different time bases, as described in Table 4. The window width for the _Reference DC trigger_ was chosen to match the half cycle of the 50 Hz grid voltage. In the case of the _DC Delta trigger_, the width of the time window was selected considering the ten/twelve cycle aggregation stated in the IEC 61000-4-30 standard [17]. Finally, the window width for the _DC Slope trigger_ was adjusted to be able to capture fast signals such as transients and spikes. Table 4 also shows the chosen thresholds for unattended operation of the system. The _DC Reference trigger_ thresholds were adjusted to be \(\pm\)10% of the nominal bus voltage (48 V). The other two thresholds were empirically adjusted using manually captured data to avoid triggering with the baseline noise.  
Since the acquisition system began unattended operation, a collection of waveforms showing different phenomenology has been acquired. These waveforms are being analysed offline to identify features and refine the trigger mechanisms. Figure 8 shows one event triggered by voltage _DC Reference trigger_, featuring all the stored signals: DC (Figure 8a) and AC (Figure 8b) voltage and current.  
Figure 7: Triggered event for voltage interruption (low and high sampling rate signals).  
The three DC signal-based triggers have been working properly, allowing the capture of waveforms with different phenomenology. Figure 9a shows an event that surpassed the top threshold (54 V) of the _DC Reference trigger_, while Figure 9b displays the same event zoomed to the width of the relevant time window (10 ms). An event captured with the _DC Delta trigger_ is shown in Figure 9c and zoomed in on in Figure 9d (200 ms time window). These events are usually associated with the end of the charge of the batteries and the beginning of energy exporting, producing an overshoot in the DC bus voltage. This effect is also seen in the data collected by the SCADA system of the micro-grid, shown in Figure 9e.  
Concerning the _DC Slope trigger_, it allowed for capturing another kind of event showing up in the micro-grid as seen in Figure 10a (zoomed in on in Figure 10b, 125 \(\upmu\)s time window) displaying an isolated disturbance in the DC level. These events are much faster and can be triggered due to the shorter time window width of this trigger.  
Finally, it is worth noting that any AC event has triggered the AC PQ-based trigger in the whole measurement campaign. This is a signal of the good operating conditions of the AC grid at the point of coupling, as those triggers use the thresholds and limits stated in the EN 50160 standard [21].  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Trigger Type** & **Window Width** & **Threshold** \\ \hline Reference & 10 ms & [54 V, 42 V] \\ Delta & 200 ms & \(\pm\)0.75 V \\ Slope & 125 \(\upmu\)s & 20 V/ms \\ \hline \hline \end{tabular}
\end{table}
Table 4: Time windows width and thresholds for different DC triggers.  
Figure 8: Triggered events in the real micro-grid: DC (**a**) and AC (**b**) signals.  
Figure 9: Triggered events in the real micro-grid (**a**,**c**) associated with DC bus voltage overshoot (**e**).