# Flexible Simulation Platform for Generating Realistic Waveforms with Voltage Notches
## 5 Comparison of Simulations with Field Measurements
### Simulation Setup and Waveform Comparison  
Through extensive analysis of voltage and current waveforms from simulations in Section 4, it was observed that Scenario 3 from Table 5, with a detuned capacitor bank as depicted in the network topology of Figure 15, matches the behavior of voltage and current waveforms from the field. In setting up the simulation, a challenge was faced due to unknown specific parameters of the installation, such as the exact short-circuit power at the PCC and the rated power of the rectifier. While these parameters would typically remain constant for a given installation, they were varied within plausible ranges in the simulations to account for uncertainties  
Figure 14: Impact of background distortion on voltage notch waveforms (**top**), input line currents of the rectifier (**middle**), and total line currents of the LV installation (**bottom**). (**a**) Non-detuned capacitor bank and (**b**) detuned capacitor bank. and to explore the sensitivity of the voltage notch characteristics to these parameters. This approach allowed a closer match to the observed waveforms to be achieved despite the lack of detailed installation data. Unknown parameters in Figure 15 can be roughly estimated by closely examining field measurements. The resulting estimated parameters are then used to set up the simulation platform to obtain similar synthetic voltage and current waveforms. At first glance, \(\alpha\) can be directly estimated by observing the Point-On-Wave (POW) of voltage notches. Likewise, the fundamental component of current in the field measurements indicates a possible range for the rated current drawn by the rectifier and linear load, and the corresponding values of \(S_{r}\) and \(S_{ll}\). Significant values of \(d_{com}\) observed in the voltage measurements suggest that the recommended value of 0.015 in the ratio \(S_{r}/S_{sc}\) is exceeded or that the commutation reactor \(X_{com}\) is not sized according to technical recommendations. In this case, proper sizing of \(X_{com}\) is assumed for \(d_{com}=0.4\) (slightly below the recommended limit for dedicated systems, see Table 1), with \(S_{r}/S_{sc}>0.015\). Moreover, the phase shift between fundamental voltage and current indicates the necessity of a capacitor bank in the installation to prevent a very poor \(PF\), probably with a detuning reactor, as natural frequencies seem not to be excited. Although the short-circuit power at a particular installation would not change significantly over a short time frame, this parameter was adjusted in the simulations to account for possible variations in the network conditions that were not captured in the measurements, such as changes in upstream network impedance due to network reconfigurations or varying load conditions elsewhere in the network. Ideally, the rated power of the rectifier should be fixed for a single installation. However, due to the absence of specific data regarding the rectifier's rated power, a range of values was simulated to find the best fit with the measured waveforms. This was necessary to compensate for the unknown actual loading conditions and potential deviations in the rectifier's performance over time. Through this general analysis and considering the single field measurement record depicted in Figure 16 (left), a similar result is obtained from a simulation, as illustrated in Figure 16 (right), with parameters \(S_{sc}=4\) MVA, \(S_{r}=160\) kVA, \(X_{com}=44.3\) m\(\Omega\), \(\alpha=78^{\circ}\), \(S_{ll}=19\) kVA, \(PF_{ll}=0.85\), and \(Q_{cb}=120\) kVA. The simulation results show significant qualitative similarities in voltage and current waveforms. The depth and width of notches are very similar, as are the phase shift and shape of current waveforms. However, some apparent differences are observed in the commutation oscillations of both voltages and currents. Figure 17 presents a more detailed comparison of the voltage and current waveforms from Figure 16. The top row in Figure 17 displays overlaid notches for each phase.