Method for calculating short circuit current of double-fed motor by considering Chopper protection

A short-circuit current and calculation method technology, which is applied in calculation, electrical digital data processing, special data processing applications, etc., to achieve the effect of improving accuracy and ensuring safety

Inactive Publication Date: 2017-05-31
HOHAI UNIV
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Problems solved by technology

However, the use of Chopper protection will inevitably suppress the short-circuit current, making the actual value of the short-circuit curren...

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  • Method for calculating short circuit current of double-fed motor by considering Chopper protection
  • Method for calculating short circuit current of double-fed motor by considering Chopper protection
  • Method for calculating short circuit current of double-fed motor by considering Chopper protection

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Embodiment Construction

[0041] The present invention will be further described below in conjunction with the accompanying drawings. The following examples are only used to illustrate the technical solution of the present invention more clearly, but not to limit the protection scope of the present invention.

[0042] The short-circuit current calculation method of double-fed motor considering Chopper protection includes the following steps:

[0043] Step 1, assuming that a three-phase short-circuit fault occurs on the stator side at time t=0, t=0 + All the time devoted to Chopper protection.

[0044] The impedance expression of Chopper protection is,

[0045] Z ch =R ch / / jω r C ch ≈R ch -jω r R ch 2 C ch

[0046] Among them, Z ch is the equivalent impedance of Chopper protection and DC bus capacitor, R ch Protection resistor for Chopper, C ch is the DC bus capacitance, ω r is the angular velocity of the rotor.

[0047]Step 2. According to the transient equivalent circuit of the doubl...

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Abstract

The invention discloses a method for calculating a short circuit current of a double-fed motor by considering Chopper protection. When the short circuit current of the double-fed motor is calculated, the influences of Chopper resistance and direct current bus capacitance on the calculation for the short circuit current are considered, so that the magnitude of the short circuit current under the short-circuit state of the double-fed motor can be more accurately expressed. Compared with a present formula, the method has the advantages that the calculation precision is improved, and the method has significance in accurately selecting materials for electric equipment and guaranteeing the safety of a wind power plant.

Description

technical field [0001] The invention relates to a method for calculating the short-circuit current of a doubly-fed motor considering Chopper protection, and belongs to the technical field of wind farm safety. Background technique [0002] At present, most of the double-fed wind turbines have added Chopper protection, which improves the low-voltage ride-through capability of DFIG and ensures the safe and stable operation of the wind farm. However, the use of chopper protection will inevitably suppress the short-circuit current, making the actual value of the short-circuit current lower than the calculated value used as the standard for selecting electrical equipment during design, thus causing unnecessary economic investment. Therefore, there is currently a need for a method for calculating the short-circuit current more accurately under the condition of using the chopper protection. Contents of the invention [0003] In order to solve the above technical problems, the pre...

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Application Information

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IPC IPC(8): G06F17/50
CPCG06F30/398
Inventor 潘文霞刘明洋张艺博郭家圣杨刚李建成陈昕
Owner HOHAI UNIV
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