Sensorless DC-link control approach for three-phase grid integrated PV system.

• Sensorless control method to establish a DC-link voltage. • Removal of the outer control loop to reduce the inverter control complexity. • Modelling and control of the grid-connected inverter. • Implementation of incremental conductance based MPPT algorithm to search an operating point for the boost converter. In this paper, a novel control approach for a grid-connected photovoltaic system (GCPVS) has been proposed. This novel approach introduces a sensorless DC-link voltage control for two-stage three-phase GCPVS. The two-stage system with the proposed control approach includes an intermediate (DC-DC boost) converter and pulse width modulation (PWM) strategy based voltage source inverter (VSI). In the first-stage control, the intermediate converter is incorporated with the maximum power point tracking (MPPT) technique. The incremental conductance MPPT technique is implemented to enhance the voltage level of the PV array under variable irradiance condition. Further, the second-stage control of VSI deals with DC-link voltage regulation (outer-loop) and current control (inner-loop) matching with the conventional scheme. Distinctively, the proposed scheme avoids the outer-loop and controls the inner-loop. Hence, the reduction of DC-link high voltage sensor minimizes the cost as well as the size of the system. However, the DC-link voltage will remain maintained through the power balancing. Hence, the removal of the outer-loop controller enhances the system stability and the dynamic response of the system under variable irradiance conditions. The proposed GCPVS is simulated in MATLAB/Simulink using sim power tools to verify the system performance and the dynamic behaviour at different irradiance levels of the system. [ABSTRACT FROM AUTHOR]