## 4 Quasi-Dynamic Simulation in PowerFactory  
Since the input data is now ready and for each parameter there is a separate comma-separated value file, they can be assigned to their respective elements on PowerFactory. The next step is to run the Quasi-Dynamic (Q-D) simulation. The Q-D simulation is run in hourly steps for a period of two years. For software reasons, in the backstage, the simulations are run separately for each year and then concatenated. The Q-D analysis means that PowerFactory will run a load flow for each hour, every single time with different data for the inputs. And for each of the 17,520 h, it will store the correct position of all automatic tap changers. When the simulation is finished, the results can be exported externally and processed as needed. The exported data will be organized into inputs, or features, that were fed to PowerFactory, and the outputs, or labels, which were calculated by PowerFactory. Data for each hour will serve as one training example and it will be used to train the DNN. The tap positions of all E-OLTCs and LVRs that change hour by hour are shown in Figure 8. The figure shows visually how the taps are adjusted to keep the voltage within the set range of \(\pm\)10%Vn. Depending on the transformer, the tap changer will be on either the HV side or the LV side.  
The four scenarios mentioned in Section 2 are run individually to better understand and compare E-OLTCs and LVRs as voltage regulating methods:  
* S1: E-OLTC off and LVR off (Figure 9)
* S2: E-OLTC off and LVR on (Figure 10)
* S3: E-OLTC on and LVR off (Figure 11)
* S4: E-OLTC on and LVR on (Figure 12)  
Figure 7: PV outputs–zoomed in a random short period.  
Figure 8: Tap positions in a random period resulting from PowerFactory simulation.  
Figure 9: Voltage profiles along the feeder when E-OLTCs are off and LVRs are off.  
Figure 11: Voltage profiles along the feeder when E-OLTCs are on and LVRs are off.  
Figure 10: Voltage profiles along the feeder when E-OLTCs are off and the LVRs are on.  
Since the DG penetration is very high, the feeder experiences unacceptable levels of over-voltages in cases where there is no type of voltage regulation in place such as in scenario S1.  
The over-voltage constraint violations are counted for each scenario and summarized in Table 1. The count considers each busbar for each hour of the entire duration of the analysis. So, the theoretical maximum of constraints would be 17,520*9.  
The results are within expectations. The more regulations, the fewer violations. That is why, when combining both LVRs and E-OLTCs, there are the fewest instances of over-voltages. The second-best method is using E-OLTCs only. Significantly worse performance is noted if only LVRs are used. It must be noted that this may be due to the specific topology of this feeder, and as such, it does not represent a generalized finding. Lastly, as expected, the highest number of over-voltage instances occur when there is no voltage regulation at all. It could be said that the topology and the length of lines, the load distribution throughout the feeder, and DG penetration, are all contributing factors to render one method better or worse than the other. In any case, combining both methods yields the best results in any feeder configuration.  
\begin{table}
\begin{tabular}{c c c c c} \hline  & **E-OLTC Off** & **E-OLTC Off** & **E-OLTC On** & **E-OLTC On** \\  & **LVR Off** & **LVR On** & **LVR Off** & **LVR On** \\ \hline V \textgreater{} 1.05 p.u & 15,652 & 6754 & 473 & 443 \\ \hline V \textgreater{} 1.10 p.u & 3742 & 655 & 0 & 0 \\ \hline \end{tabular}
\end{table}
Table 1: Over-voltage violations in one year.  
Figure 12: Voltage profiles along the feeder when E-OLTCs are on and LVRs are on.