Tailor-made Power-angle Characteristic: A New Controller Design Perspective for Grid-Forming Inverter

The ever-increasing penetration level of renewable energy sources (RESs) makes the future power system dominated by power-electronics devices. To support the system voltage and improve the frequency regulation, the grid-forming inverters are widely adopted. Recently, various active power controllers (APCs) have been developed for the grid-forming inverter, such as droop control, the power synchronization control (PSC), and the virtual synchronous generator (VSG) control. Since the APC establishes a relationship between the active power and the phase angle, its control design significantly affects the synchronization stability, the frequency regulation performance, as well as the steady-state power sharing with other generation units. This paper explores the possibility of designing APC with a tailor-made power-angle characteristic. The generalized APC transfer function and design rules will be elaborated in order to provide new insights into the grid-forming inverter control design. Based on these, a new APC is developed and compared with the conventional ones.