A novel MPPT technique to increase accuracy in photovoltaic systems under variable atmospheric conditions using Fuzzy Gain scheduling

ABSTRACT

Photovoltaic (PV) system has gradually become a research focus in the field of renewable energy power generation, and the output efficiency of PV system is the major concern of researchers. There are obvious non-linear characteristics in the output of PV system, and it will be greatly affected by the external environment. For achieving the maximum output power, PV system must operate under the guidance of maximum power point tracking (MPPT) methods. The tracking time and accuracy of these methods need to be improved. Therefore, this study contributes to increasing the output efficiency of PV system by improving the tracking time and accuracy with using Fuzzy Gain Scheduling of Proportional-Integral-Derivative (FGS-PID) regulator in the grid-connected mode. The suggested adaptive FGS-PID scheme is implemented using two-level control system architecture, combining the benefits of fuzzy logic as well as conventional PID regulator. Ziegler–Nichols tuning method is employed to select the initial values of PID gains. In the simulations of PV system under the varying irradiance and temperature, the tracking speed and tracking accuracy of FGS-PID (scaling factors) were higher than those of ANN, ANFIS, Fuzzy, INC, P&O, PID, and FGS-PID methods. In summary, FGS-PID (scaling factors) has better performance in tracking time and accuracy than other comparison algorithms. It can improve the output efficiency of PV system in practical application.

KEYWORDS:

• PV system
• Renewable energy
• FLC based MPPT
• Adaptive
• DC-DC converter

A description of the detailed model

PV parameters: Output power = 7.3 kW, Carrier frequency in VMPPT PWM generator = 5.3

KHz and in grid-side controller = 4 kHz, Buck converter parameters: L = 3.7 mH, C = 630 μF, PI coefficients in grid-side controller: K_pVdc = 3.7, K_iVdc = 6.3, K_pId = 5.4, K_iId = 343, K_pIq = 5.4, Ki_Iq = 343.

Loads: Load1 = 7.3 kW

Appendix

Appendix A: description of the detailed model PV parameters: Output power= 7.3 kW, Carrier frequency in VMPPT PWM generator= 5.3KHz and in grid-side controller= 4 kHz, Buck converter parameters: L=3.7 mH, C= 630 μF, PI coefficients ingrid-side controller: KpVdc= 3.7, KiVdc= 6.3, KpId= 5.4, KiId=343, KpIq= 5.4, KiIq= 343.Loads: Load1=7.3 kW.