Abstract:

This paper proposes a control method of AC-excited power supply for variable-speed constant-frequency (VSCF) wind energy generation with doubly-fed induction generator (DFIG). Based on grid voltage orientation, rotor-side converter and grid-side converter are studied. By analyzing the mathematical model of DFIG, the control strategy of idle load grid-connection is designed. It realizes grid-connection without impact current under variable wind speed. The grid-side converter is controlled by direct current control, achieving bidirectional energy flow and power factor adjustment. DFIG wind energy generation can be realized both in subsychronous and supersynchronous operations. Experiments show accuracy of the theory and effectiveness of the control strategy.

Key words: variable-speed constant-frequency (VSCF); doubly-fed induction generator (DFIG); AC-excited power supply; grid voltage orientation; idle load grid-connection; direct current control