Review: Grid-Connected Inverter with Its Filter and Providing Suggestions for Designing a Transformerless Inverter

The grid-connected inverter is the interconnect between a renewable energy source such as the wind and solar power and the grid. There are two types of the gridconnected inverter based on the transformer. These are called the transformerless inverter and isolated inverter. The former is a smaller size and weight; however, the one limitation of this inverter is a leakage current problem. The latter has the advantage of being applicable in isolated locations, but it suffers from high cost and significant weight. In general, the grid-connected inverter has required a filter to mitigate the harmonic components and produce a perfect sinusoidal waveform. But this filter should be properly selected, whether the L filter or LCL filter. This paper reviews the previous studies on the grid-connected inverter and highlights the limitations from the literature’s point of view. Finally, suggestions and recommendations for designing the filter and an optimal control for the gridconnected inverter are presented with extensive and indepth detail. 