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Synchronous generator rotor turn-to-turn short circuit monitoring method based on excitation magnetic potential calculation

A technology of synchronous generator and excitation magnetic potential, applied in the direction of measuring electricity, measuring devices, measuring electrical variables, etc., can solve problems such as limitations and lack of installation conditions for branch current transformers, and achieve the effect of effective monitoring

Inactive Publication Date: 2012-12-26
BEIJING JIAOTONG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] However, since the neutral point of most large steam turbine generators in China only leads to three terminals, and there is no installation condition for branch current transformers, the rotor winding inter-turn short circuit fault monitoring method based on branch unbalanced current is applied to large steam turbine generators. Wheel generators are limited

Method used

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  • Synchronous generator rotor turn-to-turn short circuit monitoring method based on excitation magnetic potential calculation
  • Synchronous generator rotor turn-to-turn short circuit monitoring method based on excitation magnetic potential calculation
  • Synchronous generator rotor turn-to-turn short circuit monitoring method based on excitation magnetic potential calculation

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Embodiment Construction

[0037] First, the basic principle of the present invention is briefly introduced.

[0038] by image 3 The secluded pole synchronous motor shown in (a) is taken as an example. The excitation winding of the motor is composed of four sets of coils 11', 22', 33', and 44' connected in series. When the excitation winding is normal, the waveform of the excitation magnetomotive force is as follows: image 3 As shown in (b), the amplitude F of the staircase wave f =N f I f / 2, where N f is the total number of turns of the field winding, I f is the excitation current. The Fourier decomposition of the step wave magnetomotive force can obtain the amplitude F of the fundamental wave magnetomotive force f1 =k f f f .

[0039] Assuming that a partial turn-to-turn short circuit occurs in the winding 11', the distribution of the excitation magnetomotive force after the short circuit is as follows: image 3 As shown in (c), due to the reduction of the effective number of turns of th...

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Abstract

The invention provides a synchronous generator rotor turn-to-turn short circuit monitoring method based on excitation magnetic potential calculation and belongs to the field of primary device relaying protection and online monitoring technology in an electric power system. The synchronous generator rotor turn-to-turn short circuit monitoring method is characterized in that first, phase voltage, phase current and stator leakage impedance of a generator are used to work out excitation magnetic potential in actual operation; second, according to exciting current on the same operating condition, excitation magnetomotive force which a normal exciting winding should generate can be calculated; and in normal operation, calculating results of two excitation magnetomotive force should be identical, but the actual excitation magnetomotive force can be smaller than the calculating result obtained according to the normal exciting winding when rotor turn-to-turn short circuit happens, and therefore a breakdown criterion is formed. An experiment that the rotor turn-to-turn short circuit happens to a typical synchronous generator in load operation condition indicates that the synchronous generator rotor turn-to-turn short circuit monitoring method can be used to achieve monitoring to rotor turn-to-turn short circuit faults and can be applied to synchronous generators which are not provided with the condition of installing branch current transformers.

Description

technical field [0001] The invention belongs to the technical field of relay protection and on-line monitoring of main equipment in a power system, and in particular relates to a method for monitoring short-circuit faults between turns of synchronous generator rotors based on calculation of excitation magnetic potential. Background technique [0002] With the rapid development of the power grid and the continuous increase of the unit capacity of generators, people put forward higher and higher requirements for the safe and reliable operation of generators. Rotor turn-to-turn short circuit is an electrical fault that often occurs in generators. A slight turn-to-turn short circuit will not have a serious impact on the operation of the generator, but if the fault continues to develop, it will cause the excitation current of the generator to increase, the output reactive power to decrease, and vibration exacerbation of adverse effects. Local overheating at the short-circuit poi...

Claims

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Application Information

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IPC IPC(8): G01R31/06
Inventor 郝亮亮吴俊勇
Owner BEIJING JIAOTONG UNIV
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