Three-phase short circuit current calculating method for double-fed motor

Abstract

The invention discloses a three-phase short circuit current calculating method for a double-fed motor. The method comprises calculating the stator side equivalent reactance after short circuit; calculating and obtaining the stator side linkage initial value and the rotor side linkage initial value before short circuit according to the stator side equivalent impedance after short circuit and the double-fed aerogenerator electromagnetic transient equation under the space rotating coordinates; calculating and obtaining the transient stator side linkage and the transient rotor side linkage according to the stator side linkage initial value and the rotor side linkage initial value before the short circuit; calculating and obtaining the stator side current according to the transient stator side linkage and the transient rotor side linkage; and obtaining the short circuit for A-phase, B-phase and C-phase, the short circuit current instantaneous maximum value and the short circuit current periodic component effective value by performing transformation of coordinates for the stator side current. The three-phase short circuit current calculating method for a double-fed motor is higher in calculating accuracy.

Description

Technical field [0001] The invention relates to the technical field of electrical economic safety analysis and design of wind farms, in particular to a method for calculating three-phase short-circuit current of a doubly-fed machine. Background technique [0002] At present, the widely used doubly-fed wind turbines in commercial applications generally use Crowbar protection, which ensures that the wind turbines can still be connected to the grid in the event of a fault, thus ensuring the safety of the wind farm. [0003] However, the use of Crowbar protection will inevitably inhibit the short-circuit current. If this point is ignored, according to the existing calculation method, the calculation result of the three-phase short-circuit current may be too large, causing unnecessary economic waste. Therefore, this patent proposes a In the case of Crowbar protection, the short-circuit current can be calculated more accurately. Summary of the invention [0004] The technical problem to ...

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Problems solved by technology

[0003] However, the use of Crowbar protection will inevitably suppress the short-circuit current. If this point is ignored, according to the existing calculation method, the calculation result of the three-phase short-circuit current may be too large, resulting in unnecessary economic waste. Therefore, this patent proposes a method using In the case of Crowbar protection, the method to calculate the short-circuit current more accurately

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