Low voltage traversing control method for double feeding wind power generator when short circuit failure of electric network

Abstract

The invention discloses a low voltage ride-through control method of a doubly fed induction aero-generator, which is used when a power network has short circuit faults. The control method is characterized in that a rotor exciting voltage positive-sequence control current and a rotor exciting voltage negative-sequence control signal are respectively formed through limiting a rotor slip frequency current and a rotor (2-s) rated frequency current when the power network has faults, and a generator is utilized for realizing the attenuation of stator flux transient DC components and reducing the rotor side influences of the stator flux transient components, positive-sequence components and negative-sequence components. The control method has the advantages that no hardware protecting device is required to be added; under the condition that the power network has symmetrical and asymmetrical faults, the overcurrent occurrence of the rotor can be effectively restrained, and the safe operations of the generator and a rotor exciting converter are protected; in the process that the power network has the faults, the transient generator impact to the power network and a mechanical system can be effectively reduced; the normal operation of the generator can be fast recovered after the faults are removed, and the timely support to the power network can be realized.

Description

technical field [0001] The invention relates to the field of operation control of a doubly-fed induction wind-driven generator, in particular to a low-voltage ride-through control method for a doubly-fed induction wind-driven generator when a grid short-circuit fault occurs. Background technique [0002] Due to its advanced and flexible operation characteristics, doubly-fed induction generators have been widely studied and applied in large-scale variable-speed constant-frequency wind turbines. As more and more doubly-fed induction wind turbines are connected to the grid for operation, the power grid has higher and higher requirements for grid-connected doubly-fed induction generators. From the perspective of stable operation of the power system, the system requires the generator set to remain connected to the system when the grid fails, and restore the machine terminal voltage as soon as possible after the fault is removed to maintain stable operation of the system, that is,...

AI Technical Summary

Problems solved by technology

[0004] The "Crowbar Protection" control method in the prior art still has the following deficiencies: ① It is necessary to add a new hardware protection device, which increases the system cost and control difficulty; ② When the power grid fails, the generator operates as an induction motor, and the unit will Absorb a large amount of reactive power from the grid, which is detrimental to the grid voltage stability; ③ During the fault process, the transient electromagnetic impact of the generator on the grid and the mechanical impact on the wind turbine are serious

Images