Large-signal black-box behavioral modeling of grid-supporting power converters in AC microgrids

Microgrids are a growing trend toward a new power distribution system that allows for a high penetration of renewable distributed generation, electrical energy storage systems and controllable loads. This modern concept exploits the advances in electronic technology to improve efficiency, reliability, and flexibility, while reducing cost and size. Furthermore, microgrids can operate in a grid-connected mode or in an islanded operation mode. Electronic power converters are essential in this kind of architecture in order to interface every element to the system. They introduce controllability into the system and dynamic decoupling. However, the control of these elements from a system-level perspective remains a challenge. The dynamic interaction among the power converters, their variable operation modes, and the lack of information about commercial converters, are some of the factors that complicate an integrated analysis. This work proposes a large-signal black-box modeling approach able to characterize the nonlinear behavior dc/ac converters. The study is particularized to a converter interfacing a renewable source with the grid. Nevertheless, this methodology can be extended to different operating modes. The performance of the model is compared with the detailed switching model of the converter.