Flexiable Fault Ride Through Capability Improvement of Semi-Direct Drive Wind Power System Based on Improved Grid-Side Control Strategy

Abstract

[Introduction] In order to improve the flexible fault ride through (FFRT) capability of semi-direct drive wind power system, this paper proposes an improved grid-side control strategy with reactive power priority. [Method] Based on the analysis of the traditional grid side control strategy, reactive power priority control was added to the traditional grid side control according to the latest test rules of fault voltage ride through capability, and reactive current was injected into the grid to support the voltage recovery during the transient faults of the grid. According to the improved grid-side control strategy, the FFRT simulation operation of wind turbine was realized by using chopper circuits combined with the improved grid-side control strategy when the deep sag and rise of the grid was realized. Combined with the 6 MW semi-direct drive wind turbine of a certain project, the fault voltage ride field test was carried out by using mobile FFRT test equipment. [Results] The test and simulation results show that the improved grid-side control strategy can improve FFRT operation of semi-direct drive wind power system and stable control of reactive current. [Conclusion] The improved grid-side control strategy can give priority to injecting the corresponding stable reactive current into the grid under various symmetric low voltage/high voltage fault conditions and asymmetric high voltage fault conditions, which can assist the voltage recovery of the grid and improve the FFRT capacity of the semi-direct drive wind power system.

Keywords

• flexiable fault ride through
• improved control strategy
• reactive current
• semi-direct drive wind power system
• chopper circuits