Dear Sir/Madam,<!--TgQPHd|||[]-->
Greetings.<!--TgQPHd|||[]-->
I have been experimenting with the parallel connection of two photovoltaic (PV) power converters and have encountered problems that I am unable to resolve.<!--TgQPHd|||[]-->
Specifically, I am analyzing two PV converters that are connected in parallel on the AC side, while their DC-side PV arrays can be considered to be connected in series. When I use isolation transformers between the grid and the AC side of both converters (Case 0), the system operates entirely according to my expectations and remains stable. Even when I remove one isolation transformer from Case 0 while keeping the other, the entire system still operates properly and stably. However, if I remove both isolation transformers from the model (Case 1), a system-wide malfunction occurs. This is manifested by oscillations in the DC quantities (current, voltage, and power), and PV converter No. 2 (PV_C_2) is unable to deliver power.<!--TgQPHd|||[]-->
I have searched for reasons in the literature and via AI, where I found that the issue might be caused by circulating currents between the two parallel-connected inverters, due to their PWM generators not being synchronized. Please let me know if you can help me improve the model to achieve synchronization between the two inverters, so I can attempt to resolve this drawback that way. I tried adding an external PWM signal to each inverter, but I was unsuccessful and do not see a way to synchronize the signals.<!--TgQPHd|||[]-->
What is your opinion? Would this approach solve the problem? Is there an example of external control available somewhere?<!--TgQPHd|||[]-->
I look forward to hearing from you as soon as possible.
Duško Tovilović, dipl.inž.el.
PhD student
Ulica akademika Jovana Surutke br. 19
78000 Banjaluka,
Bosna i Hercegovina
