# Classic Discrete Control Technique and 3D-SVPWM Applied to a Dual Unified Power Quality Conditioner
## 4 Results  
The parameters of the transformers, compensators, and the network are given in Table 1. Some of these terms were defined for equations and figures used in Sections 1 and 2 as parameters per phase of the circuit (a, b, and c); however, in this table those parameters and values are given per phase, omitting the letters. The power is supplied by a 110 V\({}_{\text{FMS}}\) three-phase source that is set unbalanced and contaminated by harmonics. Besides, at a certain time during the simulation, a voltage drop of 10% is generated in the three phases of the power source to verify the behavior of the compensator under this type of transient event. The load considered four AC-DC converters, three full-wave rectifiers to generate unbalances in the load, and a full-wave rectifier controlled by six thyristors to handle delays in the current. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Name** & **Parameter** & **Value** \\ \hline Inductance of the series APF & \(L_{s}\) & 650 \(\mu\)H \\ Switching frequency & \(Fs\) & 20 kHz \\ DC link voltage & \(V_{B}\) & 400 V \\ PWM voltage gain & \(V_{m}\) & 0.091 V \\ Power grid resistance & \(R_{rd}\) & 0.04 \(\Omega\) \\ Power grid inductance & \(L_{rd}\) & 107 \(\mu\)H \\ Power grid capacitance & \(C_{s}\) & 1 \(\mu\)F \\ Shunt inductance & \(L_{p}\) & 1.2 mH \\ Shunt and series resistance & \(R_{p}=R_{s}\) & 0.44 \(\Omega\) \\ Magnetizing resistance of the transformer & \(R_{m}\) & 104 \(\Omega\) \\ Magnetizing inductance of the transformer & \(L_{m}\) & 104 H \\ Secondary equivalent resistance & \(R_{eq\_s}\) & 0.48 \(\Omega\) \\ DC bus total capacitance & \(C_{B}\) & 3 mF \\ Secondary equivalent inductance & \(L_{eq\_s}\) & 757 \(\mu\)H \\ Primary equivalent inductance & \(L_{eq\_p}\) & 1.85 mH \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Parameters of the transformers, compensators, and the network. Figure 14: Controllers simulation scheme. Figure 15a shows the voltage with harmonic distortion in the source, the voltage improved in the load, the voltage reference, and the voltage error of the circuit with the proposed solution. Figure 15b shows the enlargement of the waves referred to the voltages measured in the source and in the load, compared to the voltage reference. A frequency analysis of the voltage waveforms measured in the source and in the load illustrates the improvement in the harmonic distortion index THD\(v\) (in percentage) after the action of the voltage compensator. These results show that the value changes from 14.97% to 1.43%, when applying the compensation, demonstrating the effectiveness of the method. When observing the enlargement of the waves, where an approach has been made to one of the positive half-cycles, the results show that the error between the voltage in the load and the voltage reference is very small, thus achieving a good performance of the compensator. The small ripple in the waveform of the voltage in the load (\(V_{Load}\)) is given by the commutation of the inverters. Figure 16a shows the current in the source and in the load, the current reference, and the current error. This figure shows that the current in the load is highly contaminated by harmonics and with a delay of 30\({}^{\circ}\) with respect to the current in the source, thus acting as a non-linear inductive load. The error between the current in the source and the current reference is less than 5% except for small peaks due to the switching frequency. The detail of the current compensation is better appreciated in the waveforms of Figure 16b, where a mid-period approach of the waves has been made. It can be seen that the total harmonic distortion in current (THD\(i\)) goes from a value of 30.94% to 3.37% taking into account the switching frequency of 20 kHz; and if only the harmonic 50 (3 kHz) is considered, the value of THD\(i\) = 2.50%, which is half of the maximum value recommended by the IEEE 519 standard. Figure 15: Voltage compensation results: (**a**) three-phase signals and (**b**) zoom of the waveform.