Control Of Utility Interfaces In Low-voltage Microgrids

• Main Author: Tenti, Paolo
• Publication Date: 2015
• Other Authors: Caldognetto, Tommaso, Buso, Simone, Danilo I. Brandao
• Format: Article
• Language: eng
• Source: Eletrônica de Potência (Online)
• Download full: https://journal.sobraep.org.br/index.php/rep/article/view/508
• topic: Distributed Generation; Grid-connected Operation; Islanded Operation; Microgrid; Utility- interactive Inverter

This paper presents a general control technique for utility interactive inverters in low-voltage microgrids. The Utility Interface (UI) is a three-phase power conversion unit, equipped with energy storage, which governs the interaction between the utility grid and the microgrid. The UI is in charge of several functions: in grid-connected operation, it performs as a voltage-supporting unit and compensates the reactive power, unbalance, and distortion caused by loads, whereas in islanded operation, it performs as a voltage- forming unit and sets the voltage and frequency for the entire microgrid. Moreover, the UI ensures seamless transitions from grid-connected to islanded operation and actively decouples the microgrid and the mains. Finally, the UI can perform as a centralized microgrid controller for distributed energy resources. The UI is therefore a crucial component, which needs to be analyzed carefully to ensure safe and reliable operation for the microgrid. This paper discusses a control approach that provides all required functionalities and ensures proper microgrid operation even in case of non- intentional islanding or severe load transients. The experimental results show the behavior of the system in different scenarios.