# Multi-Point Time-Synchronized Waveform Recording for the Analysis of Wide-Area Harmonic Propagation
## 4 Results
### Multiple Harmonic Sources Energized by Public Grid
Therefore, based on the Equation (22), the following holds:  
\[\underline{U}_{\text{emission}}=\underline{U}_{\text{PCC}-h}-\underline{U}_{U-h} \tag{22}\]  
Figures 16 and 17 demonstrate Substation A estimated voltage harmonic phasors for background distortion and voltage emission, respectively. The individual phasors of harmonic currents of equipment connected to the Substation A are shown in Figures 18 and 19. Figure 10:0 5 th harmonic voltage emission phasors at LV side of Substation A (in volts). Test sequence B.4—public grid supply. Figure 10:1 5 th harmonic current phasors of EV at Substation A (in amperes). Test sequence B.4—public grid supply. Figure 20 shows the result of harmonic current vectorial summation at LV side of substation A. It can be observed that, in that case, emulated harmonic load acts as the dominant source of harmonic current at 250 Hz. The harmonic voltage drop produced by this harmonic current (Figure 17) ensures a certain level of harmonic cancellation when added to the estimated voltage background phasors (Figure 16) with final measured values settled below the initial background levels (Figure 21). Figure 10:2 5 th harmonic current phasors of Triphase at Substation A (in amperes). Test sequence B.4—public grid supply. Furthermore, an example of harmonic processes taking place synchronously for 350 Hz harmonic at Substation G is shown in Figures 22 and 23. Despite the dynamic nature of PV power, it is to observe that harmonic voltage emissions phasors at 350 Hz are localized at the 1 st quadrant of unity pane. Given the phasors of voltage background distortion located at the 4 th quadrant, the conclusions that a small harmonic cancellation took place within this specific substation can be made. Figure 10:3 5 th harmonic voltages (RMS) at Substation A. Test sequence B.4—public grid supply. Figure 10:4 7 th harmonic background voltage phasors at LV side of Substation G (in volts). Test sequence B.4—public grid supply. Finally, a small selection of average quantitative results derived by means of synchronized phasors and Voltage Harmonic Vector Method is collected in Figure 10:5  
Furthermore, it is interesting to observe the time-evolving harmonic current behavior of EV charger demonstrated in Figure 10:6 The harmonic injections of this type of power-electronic devices are highly sensitive to the changes of applied harmonic background voltage, both in terms of magnitude and phase angles. This effect is attributed to the underlying topology of the equipment, namely to the type of power factor correction circuit [11; 19]. As it can be seen from synchronized harmonic trends, for every studied frequency, the current injections of EV charger exhibit nearly linear behavior in response to the background voltage distortion. This phenomenon renders such multi-point harmonic measurements to be important in an attempt to identify sources of disturbances and to quantify harmonic emissions. Figure 10:7 7 th harmonic voltage emission phasors at LV side of Substation G (in volts). Test sequence B.4—public grid supply. Figure 10:8 EV charger harmonic currents. Test sequence B.4—public grid supply.