Rotor Voltage Compensation Control Strategy of Double-fed Wind Turbine Considering Stator Flux Transient Characteristics

Abstract

The stability of the grid voltage is directly related to the stability of the DFIG operation, which is related to the topology of the DFIGURE After the grid failure, the rotor current will be too large if the stability threshold is exceeded continuously. The current low voltage control uses additional hardware measures to make the wind turbines survive under the impact of grid voltage drop. Because additional hardware measures will increase the investment of the system, this paper proposes an additional control of the rotor-side converter of the double-fed wind turbine considering the stator flux linkage. The output voltage of the converter is increased through the compensation of additional control to suppress the excessive rotor current. Firstly, the dynamic process of the double-fed wind turbine can be obtained from the relationship between stator flux linkage and rotor voltage of the circuit before and after the fault, and the rotor equivalent circuit is obtained. Combined with the actual control of the rotor converter, the rotor current composition in different coordinate systems is obtained. Compared with the two current components, the equivalent relationship can be obtained to get the transient voltage to be compensated. The rotor converter increases the corresponding output voltage to prevent excessive rotor currents from affecting wind power systems. The simulation proves that the proposed additional control can limit the transient current of the fan rotor in a safe range when the grid voltage drops, which enhances the anti-interference ability of the double-fed wind turbine.