Impact of DFIG on Weak Grid Stability

This paper primarily investigates the impact of doubly-fed induction generators (DFIG) on weak grid stability. First, we need to understand what a DFIG is. A DFIG is an asynchronous generator commonly employed in wind turbines. It utilizes power electronic devices on the rotor side to enable control over rotor voltage and current. This design allows the generator to maintain relatively stable output voltage and current during wind speed variations through sophisticated control algorithms.

Returning to our main topic, DFIGs significantly influence weak grid stability. In weak grids, voltage and frequency levels are typically lower, making the system more susceptible to external disturbances. The power control characteristics of DFIGs can help mitigate these effects. Since DFIGs can control voltage and current on the rotor side, they can adjust output voltage and frequency by regulating rotor-side power through control algorithms like vector control or direct power control, thereby enhancing grid stability.

Furthermore, DFIGs can assist in maintaining voltage and frequency stability by providing reactive power support. In weak grids, reactive power control is crucial as it helps maintain system parameters within acceptable ranges. The power control capabilities of DFIGs enable effective management of reactive power output through q-axis current regulation in dq-reference frame control schemes, thus improving grid stability.

In summary, DFIGs play a vital role in weak grid stability. Through rotor-side power control and reactive power provision implemented via power converter control systems, DFIGs effectively help maintain grid voltage and frequency stability, thereby reducing the impact of external disturbances.