Research on Power Flow and Harmonic Interference between VSCF Wind Power Generators Under Change of Rotor Angular Velocity

摘要

Under the circumstance that doubly-fed wind power generator and direct-driven wind power generator are installed on the same box-type substation, when the wind speed can make doubly-fed wind power generator run on hyper-synchronous power generating state and with changes of rotor angular velocity, the doubly-fed wind power generator after repairing and maintenance can be transited from sub-synchronous power generating state to hyper-synchronous power generating state, absorb active power generated by direct-driven wind power generator and generate harmonic interference following power flow. However, under sub-synchronous power generating state, the rotor angular velocity of doubly-fed motor has direct relation with active power absorbed by rotor side. This paper has made theoretical analysis on active power absorbed by rotor of doubly-fed motor in sub-synchronous power generating state by equivalent circuit of doubly-fed motor under changes of rotor angular velocity, infers the real relation formula about rotor angular velocity, stator current vector and active power absorbed by rotor side and then analyzes change laws of active power absorbed by rotor under changes of rotor angular velocity by examples. Through establishing grid-connected model of VSCF wind power generator in Matlab/Simulink and make simulation of harmonic interference, the changes to root-mean-square value of total harmonic content has been calculated and change law of harmonic interference generated following power flow has been analyzed.