Hello friends,

I am working on a control strategy of a grid connected 7 Level cascaded H-bridge(CHB) with independent Maximum Power point tracking (MPPT) PV System, according to the enclosed reference papers ( they have nearly the same control strategy).

Each H-bridge is connected to a single PV module with Vmpp= 75V, and Impp= 1.4 A. The PV modules voltages and currents are not getting stable and even they are not changing although I tried to adjust the DC link capacitors and the PI voltage and current controller gains, so I thought maybe there is an issue in the Control strategy implementation. A PLL is used for synchronisation and a Phase shifted PWM (PSPWM) is implemented in this Matlab Simulink model.

Important to notice, that the model and my MPPT algorithm (P&O) is working perfectly fine with a single H-bridge, I also tried to adjust it with 7 level CHB, but no changes in the results.

Is the implementation of the control strategy right? and do you have an idea where can the issue be? I can convert and send you the file if you can help me with this.

Enclosed you find the reference papers, Control strategy scheme and the Simulation results.