An Overview of Modeling and Control of Grid-Forming Inverters

In this chapter, the modeling and control of grid-forming converters is discussed in detail. First, the basic definition and the conceptual differences between grid-forming converters and grid-following converters are discussed. Second, the model of the grid-forming converter is introduced to represent the dynamics of control system. Then, control loops of grid-forming converters, including the outer and inner loops, are studied. The main functionalities of the outer loop are power synchronization and voltage profile management. Also, the inner loop is developed for calculating the modulation signal for regulating the output voltage of grid-forming converter. Furthermore, different control structures such as cascaded control and direct voltage control with linear and fractional-order sliding mode controllers are presented. Finally, the design of controllers is demonstrated and verified with case studies.