Grid interfaced three phase transformerless PV inverter LVRT analysis using PR controller with Harmonic Compensation

Reliability is the main criterion that needs to be focused on, as Photovoltaic systems are gaining prominence in Grid level applications. In this paper, a simple yet efficient current control technique, Proportional Resonant controller with Harmonic Compensation (PR+HC) is used. The performance of the considered 3 phase Inverter topology is evaluated for Low Voltage Ride Through (LVRT) capability as per the Grid Standards. Moreoverleakage current is generated in PV systems due to lack of isolation between the PV panels and the grid. Maintaining the Common Mode Voltage (CMV) to be constant, plays a major part in power electronics converters control for transformerless PV applications. Inverter, which itself is a source of harmonics, needs an effective modulation strategy which is accomplished in this work and the PR+HC controller plays a key role in reduction of harmonics. The active and reactive power control in both the MPPT and LVRT modes is accomplished on the basis of PQ theory. The entire setup of 3 phase PV transfromerless Inverter for LVRT analysis is simulated and verified using MATLAB Simulink software.