Comparative Fault Ride Through Assessment between Grid-following and Grid-forming Control for Weak Grids Integration

The increasing penetration of renewable energy results in the grid strength to reduce, and the short circuit ratio (SCR) of the power grid decreases, which causes interference to the traditional power system's operation under a steady state. In order to mitigate such problems, the grid- forming (GF) inverter has been proposed, which is able to provide frequency support during disturbances. The configuration of different types of grid-forming control has been proposed, and their dynamic performances have been thoroughly researched. To further study the fault ride-through (FRT) capability during a three-phase balanced short-circuit fault and compare the dynamic difference between grid- following (GL) and grid-forming control, a theoretical analysis of the inverter using different control methods is conducted. The outcome demonstrates in grid-following control, large frequency variations will occur during and after the fault, while the grid-forming control has small frequency variations, it has better fault ride-through capability and is suitable to operate under a weak grid. Finally, electromagnetic transient simulations are carried out in PSCAD to verify the conclusions.