Generalized power-angle control for grid-forming converters: A structural analysis

Abstract

Several control schemes have been recently proposed and studied as grid-forming controls for power converters. In all these schemes, the power-angle control loop is the part which defines the fundamental capabilities of the grid-forming control: that control loop governs in fact the inherent synchronization mechanism of the power converter, the power sharing with the other generation sources in the system and the oscillatory characteristics of the converter-based resource. This article introduces a general formulation for the power-angle control characterizing the grid-forming concept for power converters. The generalized power-angle control is based on a polynomial fraction formulation, and it is arranged according to physical requirements and constraints. The structural analysis provides an insight into the capabilities and the design of the power-angle control loop of a grid-forming scheme. The generalized formulation is eventually applied to some common grid-forming controls like the power-synchronization control and the virtual synchronous machine, showing how the proposed generalized power-angle control can effectively realize different control structures.