ABSTRACT
The present study focuses on design and analysis of grid-connected PV system under varying irradiance and temperature. The modelling and analysis of the system are carried out in MATLAB/Simulink. The simulated model considers an array of PV panels, with a maximum power of 100.7 kW, connected to a 25 kV medium tension (MT) power utility grid via a DC-DC voltage booster, and a three-level, three-phase DC-AC power converter with natural point clamped (NPC). The maximum power point tracking (MPPT) regulator is implemented in the DC-DC converter using a sub-system block of incremental conductance (InC) algorithm. An efficient control strategy has been considered in inverter for stable operation of the system. An LC filter is also used to remove the harmonics in inverter. The active and reactive powers injected to grid along with grid voltage have been observed. Other parameters such as output voltage and current of PV, DC link voltage, inverter output current, and voltage without filter and after filtering, grid injected voltage and current at point of common coupling (PCC). have been observed. However, system characteristics change when it is under varying irradiance and temperature. Thus, performance of the system is also reported under varying weather conditions. The performance of the system under steady-state condition is found to be satisfactory. It has been observed that the power output from PV system solely depends on the solar irradiance and temperature. The DC-link voltage of PV system remains fixed with the help of controllers. Furthermore, it can be concluded that the MPPT technique plays a significant role to improve power extraction.
