Optimizing Control of Inverters in Three-level Grid-connected PV systems

As the rapid development of new energy generation technology in recent years, grid-connected inverters had been widely used. In order to reduce switching noise and harmonics, multi-level technology, and a variety of filters are applied to a large number of grid-connected inverters. In the application of passive filters, L-filter and LCL-filter are commonly used.Relative to the L-filter, LCL-filter is widely used,because of its efficient. But the extra pole introduced by LC circuit induces resonance.If the filter is not designed properly, the system will be unstable. This paper presents a method to improve this problem. Simulations and experiments show that the method can effectively improve the output of the grid-connected inverters and maintains this system stable.