Crowbar resistance setting method for doubly-fed wind generator in current frequency domain analysis

Abstract

The invention discloses a crowbar resistance setting method for a doubly-fed wind generator in current frequency domain analysis. Through frequency domain calculation, analysis of the stator-rotor current generated after a crowbar circuit is triggered in the low voltage ride through process of the doubly-fed wind generator is achieved. Under the constraint that the maximum line voltage of the crowbar circuit does not exceed the direct current bus voltage of a four-quadrant converter in the transient process and the condition that a rotor converter is reliably bypassed after the crowbar circuit is triggered, a certain rotating point within a design rotating speed range exists for different crowbar resistance values, wherein at the rotating point, the transient component decaying speed of the rotor current of a certain frequency generated after the crowbar circuit is triggered reaches the minimum extreme value. By means of the crowbar resistance setting method, the minimum extreme value reaches the maximum extreme value, the lower limit of the decaying speed of the rotor transient current generated after the crowbar circuit is triggered in the low voltage ride through process is constrained, and the response time for alternating current excitation recovery of the rotor converter is ensured.

Description

technical field [0001] The invention relates to a method for setting crowbar resistance of a doubly-fed wind power generator based on current frequency domain analysis, and belongs to the technical field of electric drive applications. Background technique [0002] The crowbar circuit realizes the bypass protection of the rotor converter of the doubly-fed wind turbine (Doubly-fed Induction Generator, DFIG) during the low voltage ride through process. When this protection method is used for control, the rotor converter loses control of the rotor current, and the transient characteristics completely depend on the parameters of the crowbar circuit. A key factor in restoring AC excitation. The analysis of the transient current of the stator and rotor during the triggering of the crowbar circuit is the technical bottleneck to realize the parameter setting. [0003] At present, there are mainly three methods for setting the crowbar resistance of doubly-fed generators: [0004] ...

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Problems solved by technology

[0007] It can be seen that at present, the crowbar resistance setting of doubly-fed generator sets mostly relies on experimental exploration, engineering experience, simulation or approximate calculation methods. In addition to the disadvantages of high cost, long cycle and low accuracy, the above methods are not effective at different speeds. Under certain conditions, the transient current decay speed after triggering the crowbar circuit is uncertain, and the response time of the rotor converter to restore AC excitation is difficult to guarantee

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