# A Novel Variable Step Size Incremental Conductance Method with an Adaptive Scaling Factor
## 4 Simulation and Experimental Results  
### Simulation Result  
MATLAB/SIMULINK software was utilized in this study for obtaining simulation results and to compare the performances of different MPPT techniques. To validate the correctness of the proposed method, this study compared the tracking performances (tracking time, tracking accuracy, and total energy loss) of different methods under various irradiance levels. In this study, the tracking time is defined as the time required for the tracking power enters the range of \(\pm\)1% of MPP, and the tracking accuracy can be calculated by dividing the sum of the power of 1 s after steady state with the ideal MPP. Figure 4 shows the tracking performance of different scaling factors (\(M\) value). In Figure 4, the irradiance level is 500 W/m\({}^{2}\) during 0-5 s and increases to 800 W/m\({}^{2}\) during 5-10 s. As shown in Table 3, when the irradiance level is 500 W/m\({}^{2}\), the optimal \(M\) value is 1.08, and the optimal \(M\) value is 0.65 when the irradiance level is 800 W/m\({}^{2}\). Therefore, this study simulated three conditions, such as an \(M\) value fixed at 0.65, an \(M\) value fixed at 1.08, and utilizing the optimal \(M\) value according to the current irradiance level. In terms of the first 5 s of the tracking process (500 W/m\({}^{2}\)), the \(M\) value fixed at 0.65 is too small compared to the current optimal \(M\) value (1.08). On the other hand, in the last 5 s of the tracking process (800 W/m\({}^{2}\)), the \(M\) value fixed at 1.08 is too large compared to the current optimal \(M\) value (0.65). As shown in Figure 4, the tracking time of a smaller \(M\) value in the first half section of Figure 4a is longer than those in Figure 4b,c. On the other hand, the larger \(M\) value in the second half section of Figure 4b results in oscillation in the steady-state compared with Figure 4a,c. However, if an appropriate \(M\) value is adopted according to the current irradiance level (Figure 4c), the dynamic tracking will be fast and the steady-state oscillation can be eliminated. Figure 3: Flow chart of the proposed method. VSS: Variable Step Size; INC: Incremental Conductance; MPPT: Maximum Power Point Tracking. Figure 5 shows the tracking performance of different scaling factors (\(M\) value) when the irradiance level decreases. In Figure 5, the irradiance level is 800 W/m\({}^{2}\) during 0-5 s and decreases to 300 W/m\({}^{2}\) during 5-10 s. As shown in Table 3, when the irradiance level is 800 W/m\({}^{2}\), the optimal \(M\) value is 0.65 and the optimal \(M\) value is 1.8 when the irradiance level is 300 W/m\({}^{2}\). Therefore, this study simulated three conditions, such as an \(M\) value fixed at 1.8, an \(M\) value fixed at 0.65, and adopting the optimal \(M\) value according to the current irradiance level. In the first 5 s of the tracking process (800 W/m\({}^{2}\)), the \(M\) value fixed at 1.8 is too large compared to the current optimal \(M\) value (0.65). On the other hand, in the last 5 s of the tracking process (300 W/m\({}^{2}\)), the \(M\) value fixed at 0.65 is too small compared to the current optimal \(M\) value (1.8). As shown in Figure 5, a smaller \(M\) value will slow down the tracking process, while a larger \(M\) value will result in steady-state oscillation during tracking. However, if an appropriate \(M\) value is employed according to the current irradiance level (Figure 5c), the optimal performance can be obtained. To further validate the effectiveness of the proposed method, this study compares four different MPPT methods under various irradiance and panel temperature values. In this study, the conventional VSS INC MPPT method using three fixed scaling factor values (0.65, 1.08, and 1.8) was compared with the proposed VSS INC MPPT technique with adaptive scaling factor. Figure 6 shows the obtained MPP tracking results.