## 3 Experimental Analysis of the Reactive Power in Nowadays Power Distribution Lines
### Experimental Analysis of the Reactive Power in PDL Loaded by Diode Rectifier Supply-Side Devices  
A photograph of the experimental setup is presented in Figure 14.  
The experimental setup, for the reactive power provided or drawn out by diode rectifier supply-side device analysis, consists of (Figure 7):  
1. PDL connection switcher;
2. METREL MI 2892 power quality analyzer;
3. Inductive reactor;
4. Diode rectifier;
5. Capacitors bank;
6. DC circuit voltage measuring device;
7. Ohmic load. The internal parameters of PDL the experimental equipment was connected \(R=0.82\ \Omega\), \(\omega L=0.2\ \Omega\). The experimentally taken results of power analysis are presented in Figures 8-10. The next step of the experiment was performed by keeping the power constant of the single-phase diode rectifier supply-side device and connecting additional inductive chokes \(\omega L_{\text{PDL}}\) to the PDL circuit. The aim was to increase the reactive power consumption of this diode rectifier supply-side device. The diagrams in Figures 10 and 11 show that \(tg\phi\) reaches 0.25, which confirms the theoretical calculations presented in Table 1 test number 7. It can also be seen that the reactive power changes the character transition from leading to lagging at a DC circuit capacity of \(1800\div 4000\ \upmu\text{F}/\text{kW}\). This experimental point also confirms the theoretical assumptions. The \(tg\phi\) as a function of the DC circuit capacity at different PDL internal resistances and inductances shows that at higher PDL internal inductances, the reactive power of the diode rectifier supply-side device shifts to lagging to a lower DC circuit capacity. The diagrams in Figure 10 correspond in nature to the diagrams in Figure 6 based on theoretical calculations. \begin{table}
\begin{tabular}{r c c c c c c c c} \hline \hline \multirow{2}{*}{**No.**} & **No. of LED Bulb** & \multirow{2}{*}{\(P_{C}\), W} & \multirow{2}{*}{\(N_{C}\), var} & \multirow{2}{*}{\(S_{C}\), VA} & \multirow{2}{*}{\(PF\)} & \(\begin{array}{c}\mathbf{Q_{VFund}},\\ \mathbf{var}\end{array}\) & & \(S_{\text{VFund}},\\ \mathbf{VA}\) & & & & & & & \\ \hline
1 and 2 & 21.9 & \(-36.7\) & 42.8 & 0.937 & \(-8.307\) & 23.8 & \(-0.378\) & 0.937 \\ \hline
1 and 2 and 3 & 36 & \(-56.6\) & 67 & 0.921 & \(-15.5\) & 39.8 & \(-0.43\) & 0.921 \\ \hline
1 and 2 and 3 and 4 & 49.7 & \(-72.7\) & 80.08 & 0.938 & \(-18.7\) & 53.9 & \(-0.367\) & 0.938 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The electrical parameters of the LED light bulbs combination connected to the PDL. Figure 7: Circuit diagram of experimental setup for the reactive power provided or drawn out by diode rectifier supply-side device analysis. As the internal inductance of the PDL increases, the pulse max value of the current flowing to the diode rectifier supply-side device shifts to the lagging power consumption side (Figure 12). The inductance and resistance of the power distribution lines with the capacitance of the VFD DC circuit form a corresponding resonant frequency with a sequential oscillating circuit. When the instantaneous value of the voltage in the power distribution lines becomes higher than the voltage in the capacitor of the DC circuit, the capacitor charges. Depending on the value of the capacitance in the DC circuit, and the value of the resistance and inductance of the power distribution lines, the charging of the capacitor may occur aperiodic and periodic, with fading oscillations during charging. This is the situation we  
Figure 8: Active and reactive power components at the point of connection of the single-phase diode rectifier supply-side device to the PDL as a function of DC circuit capacity value in case of internal parameters of PDL-connected \(R=0.82\)\(\Omega\), \(\omega L=0.2\)\(\Omega\). Figure 10: \(lg\Phi\) at the point of connection of the single-phase diode rectifier supply-side device to the PDL as a function of DC circuit capacity value in case of different PDL inductivity and resistance.