How to parallel Two three phase two level inverters in microgrid that is fed by renewables?

I have a microgrid consists of two three phase two level inverters which are operated in parallel with main grid. One inverter is fed by renewable while the other one fed by a battery-bank. When each inverter operates in parallel with main grid in either isolated or connected to main grid they do operate perfectly, but when the whole grid is assembled with two inverters in parallel with main grid, the whole grid goes in mis-function and the inverters cannot provide power to loads or inject to main grid. Here are three simulink matlab files with whole network image, that are each inverter in parallel with main grid and the whole assembled grid. the first two work fine, but the last one does not operate synchronisingly and it goes in a big swing. The scenario is: The DG Inverter1 provides power all the times unless it goes under-rate, then DG Inverter2 connects to live network for peak shaving or to charge battery-bank, in either isolated mode or grid-connected modes. You can also define any other scenario. I don't know what to do to synchronise the network when two inverters are implemented, what should I do? Is there any example available to study? Thank you very much for any help

[orlando enrique calderas bojorquez]

Hello Mehr, where you able to make it work ?? I'm facing a similar issue

Answer 1

[Sabin]

I can see why it works in isolation but not when integrating together. It seems that all inverters are trying to control the DC-link voltage, but this is not correct in this context. Assuming that the battery is operating in grid-following mode it would be more appropriate to implement a control algorithm with voltage and frequency support. A good starting point to learn about how to build and simulate solutions for renewable energy is available on MATLAB Central:

https://mathworks.com/matlabcentral/fileexchange/123870-renewable-energy-integration-design-with-simscape