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The Method of Discovering the Influence Law of Negative Sequence Components on Torque and Harmonics in Turbine Generator

A technology of steam turbine generator and negative sequence component, which is applied in the fields of electric digital data processing, instrumentation, calculation, etc., and can solve the problems such as the decline of thermal stability of motors

Inactive Publication Date: 2018-10-12
HARBIN UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to solve the problem that the thermal stability of the motor decreases due to the restriction of the internal negative sequence quantity of the rotor of the large steam turbine generator, and then provide a method for discovering the law of the influence of the internal negative sequence component of the steam turbine generator on torque and harmonics

Method used

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  • The Method of Discovering the Influence Law of Negative Sequence Components on Torque and Harmonics in Turbine Generator
  • The Method of Discovering the Influence Law of Negative Sequence Components on Torque and Harmonics in Turbine Generator
  • The Method of Discovering the Influence Law of Negative Sequence Components on Torque and Harmonics in Turbine Generator

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specific Embodiment approach 1

[0039] Specific implementation mode one: establish a turbogenerator model

[0040] 1 Basic assumptions for building the model

[0041] Ansoft simulation software is used to establish a two-dimensional electromagnetic field model. In order to determine the differential equation and boundary conditions of the magnetic field in the area to be solved, the following assumptions are made:

[0042] 1) The calculation of the magnetic field in the synchronous generator is simulated using a two-dimensional field, and the magnetic field in the generator is assumed to be a quasi-steady field, and the displacement current is ignored.

[0043] 2) Assume that the circumference of the outer surface of the stator of the generator is applied with the Dirichlet boundary condition as the boundary condition, and its value is set to zero.

[0044] 3) It is assumed that the material of the motor is isotropic, that is, the hysteresis effect of the ferromagnetic material is neglected.

[0045] 4) Ch...

specific Embodiment approach 2

[0052] Specific implementation mode two: analyze the influence of different negative sequence components on torque;

[0053] The analysis of the torque in this paper is based on the Ansoft Maxwell2D transient solver. The rotational equation used by the transient solver in the solution process is

[0054] Jβ+λω=T comp +T load

[0055] In the formula, J is the inertial force, kg m 2 ;T is torque, N m; ω is angular velocity, rad / s; β is angular acceleration, rad / s 2 .

[0056] Through the simulation of the model in the rated operating state, the torque-time image under the rated working condition is obtained, and the spectrum analysis of the torque waveform is carried out, the image is as follows image 3 , Figure 4 shown.

[0057] From image 3 , Figure 4 It can be seen that the torque of the generator is basically stable during rated operation, and its fundamental wave amplitude is 7.257MN·m, and the amplitude of each harmonic is very small and can be ignored.

[00...

specific Embodiment approach 3

[0065] Specific implementation mode three: analyze the influence of different negative sequence component changes on air gap flux density harmonics;

[0066] By changing the content of negative sequence, the air gap flux density of turbogenerator under different negative sequence components is obtained by simulation. Due to the symmetry of the generator, it is advisable to generate an air-gap magnetic density curve from a pair of poles of the generator, and decompose the curve to obtain the amplitude of each air-gap magnetic density harmonic.

[0067] The steam turbine generator decomposes the air-gap magnetic density harmonics of a pair of poles under rated operation conditions, such as Figure 8 , Figure 9 shown.

[0068] In order to explore the regular changes of each air gap magnetic density harmonic with different negative sequence current components, the generated histogram is shown as Figure 10 shown by columnar Figure 10 It can be seen that the fundamental wave ...

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Abstract

The invention provides a method for finding an influence rule on torques and harmonic waves by negative sequence components in a steam-turbine generator and particularly relates to calculation of influences on the torques and the harmonic waves by a magnetic field generated by negative sequence current components, aiming at solving the problem that the heat stability of a motor is reduced, caused by the fact that a rotor of the large-size steam-turbine generator is restricted by the negative sequence components. The method comprises the following steps: step 1, establishing a steam-turbine generator model; step 2, analyzing the influences on the torques by the different negative sequence components; step 3, analyzing the influences on gap flux density harmonic waves by the changes of the different negative sequence components; and step 4, analyzing the influences on flux density distribution when the negative sequence components are changed. According to the method provided by the invention, simulating calculation can be carried out through the steam-turbine generator under the condition that the negative sequence current components are different, and the torques are calculated and analyzed under a negative sequence operating working condition; and regular changes of the gap flux density harmonic waves of the generator are concluded and analyzed.

Description

technical field [0001] The invention relates to a method for discovering the law of the influence of negative sequence components on torque and harmonics in a turbogenerator, and specifically relates to the calculation of the influence of a magnetic field generated by negative sequence current components on torque and harmonics. Background technique [0002] When the capacity of large turbogenerators continues to increase, the strength and performance of materials have not been improved synchronously, so that the thermal stability of the generator is restricted, and the temperature of each component of the generator rises, which affects the ventilation and cooling of the generator. There are high requirements for the thermal stability of technology and materials; due to the high speed of the turbogenerator and the solid structure of the rotor, the negative sequence current component in the air gap of the generator will be synchronized with the rotor speed and rotate in a diff...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06F17/50
Inventor 戈宝军王慧陶大军王娜张睿陈政豪王文博
Owner HARBIN UNIV OF SCI & TECH
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