Decoupled-DFIG Fault Ride-Through Strategy for Enhanced Stability Performance During Grid Faults

Abstract

This paper proposes a decoupled fault ride-through strategy for a doubly fed induction generator (DFIG) to enhance network stability during grid disturbances. The decoupled operation proposes that a DFIG operates as an induction generator (IG) with the converter unit acting as a reactive power source during a fault condition. The transition power characteristics of the DFIG have been analyzed to derive the capability of the proposed strategy under various system conditions. The optimal crowbar resistance is obtained to exploit the maximum power capability from the DFIG during decoupled operation. The methods have been established to ensure proper coordination between the IG mode and reactive power compensation from the grid-side converter during decoupled operation. The viability and benefits of the proposed strategy are demonstrated using different testnetwork structures and different wind penetration levels. Control performance has been benchmarked against existing grid code standards and commercial wind generator systems, based on the optimal network support required (i.e., voltage or frequency) by the system operator from a wind farm installed at a particular location.

Enhancing LVRT of DFIG by Using a Superconducting Current Limiter on Rotor Circuit

“…The Electromagnetic Force ( e r ) induced in the rotor is the sum of two terms, e r f e e rn , Equation (11). The first term, e r f , is due to grid voltage, shown in Equation (12).…”

“…This solution provides an alternative path to rotor currents protecting the B2B converter. Its major disadvantage is that the DFIG loses its controllability once the crowbar is triggered, due to the rotor side converter deactivating [11]. In such a situation, the DFIG absorbs a large amount of reactive power from the grid, leading to further grid voltage degradation [4].…”

Comparison of Crowbar Control and Novel Control Methods for DFIG Wind Turbine to Enhance LVRT Capability under Various Faults

“…The STATCOM also helps in improvement of power quality. But the usage of big STATCOMs [6] in the wind park will result in high cost [5] of these systems and hence this will discourage their utilization.…”

Active damping of torsional vibrations in the drive train of a DFIG wind turbine

“…The new grid codes force wind turbines to stay connected to the grid during and after a voltage dip, i.e., low voltage ride through (LVRT). The conventional way to protect a DFIG wind turbine from a grid fault is by installing crowbar devices [11]- [12]. The crowbar is capable of limiting the overvoltage in the DC-Link and overcurrent in the rotorside converter.…”