Accurate power control of grid forming power converters for improving large-signal stability

Artikel i vetenskaplig tidskrift, 2023

In modern power systems, fossil-fuel powered synchronous generators are being replaced by renewable generators with power electronic converters. This has raised concerns on the stability of the power system, of which grid operators have started to establish new requirement on power converters for providing grid-forming (GFM) functionalities. In particular, for large signal disturbances in the grid, GFM power converter needs to remain synchronized to the grid and provides support to the grid according to the requirement. This paper first uses phase portrait analysis to illustrate the transient stability of a gridconnected converter with GFM control during large-signal disturbances. A simple yet effective fault-ride-through (FRT) stabilizing control scheme is proposed to improve the synchronization stability of converter. In the proposed scheme, the active power reference for the active power control loop is proportionally adjusted with respect to the grid voltage, whereas an additional reactive power is injected to the grid with respect to the absolute value of active power unbalance. In the end, time-domain simulation is conducted to illustrate the effectiveness of the proposed FRT scheme for enhancing the transient stability of the gridconnected converters with GFM control.