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An Optimal Method for Solving Unstable Equilibrium Point of Induction Motor

An induction motor, stable and balanced technology, applied in the direction of circuit devices, AC network circuits, AC network voltage adjustment, etc., can solve the problem of low solution accuracy and achieve the effect of improved solution accuracy

Active Publication Date: 2020-09-01
CENT CHINA BRANCH OF STATE GRID CORP OF CHINA +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This type of method ignores the change of the terminal voltage in the transient process of the induction motor, and directly uses the steady-state terminal voltage of the induction motor after the fault, and the solution accuracy is not high

Method used

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  • An Optimal Method for Solving Unstable Equilibrium Point of Induction Motor
  • An Optimal Method for Solving Unstable Equilibrium Point of Induction Motor
  • An Optimal Method for Solving Unstable Equilibrium Point of Induction Motor

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Experimental program
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Effect test

Embodiment 1

[0062] by figure 1 It can be seen that an optimization method for solving the unstable equilibrium point of an induction motor includes the following steps:

[0063] a. The establishment of a comprehensive load model of the actual power grid

[0064] a1. Establish a comprehensive load model of the actual power grid that takes into account line transmission reactance, constant impedance load, induction motor load and reactive power compensation device

[0065] In actual power grids, since reactive power cannot be transported in large capacity over long distances, it is usually necessary to add reactive power compensation devices at the load end of induction motors. In the actual grid calculation process, the load model is usually the induction motor load plus the constant impedance load model, such as figure 1 Shown.

[0066] The induction motor model is the rotor resistance R R With rotor reactance X R After series connection with excitation reactance X M Parallel, then with stator ...

Embodiment 2

[0114] Two sets of IEEE induction motor parameters are used, see Table 1. Each group of parameters sets the system transient voltage stability limit of 90% and 80%, respectively, the load active power is 1300MW, 1200MW working conditions, the initial power factor is 0.97, the line transmission reactance is 0.095; set separately for each working condition The load model has two load ratios: 65% induction motor + 35% constant impedance and 50% induction motor + 50% constant impedance.

[0115] Table 1 Induction motor parameters

[0116] parameterRS

XS

RR

XR

XM

Parameter one0.020.180.020.123.499 Parameter two 0.0310.10.0180.183.2

[0117] (1) Calculate the parameters of the reactive power compensation device and the constant impedance load impedance parameters of the induction motor before and after the failure according to equations (4), (9), and (2) by building a model simulation. The results are as follows:

[0118] Table 2 Parameters of reactive power compensation device and cons...

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Abstract

The invention discloses an optimization method for solving an unstable balance point of an induction motor, relating to a power system. By establishing an equivalent circuit, the method gives a methodfor correcting the parameters of the generator terminal reactive power compensation device and the line parameters after the fault, and changes the proportional parameter of the induction motor powerto the line power to enable the model to be closer to the condition of the actual power grid. The generator terminal voltage is taken as the virtual induction motor terminal voltage, avoiding the problem that the induction motor terminal voltage is not constant during the transient process after the fault; virtual electromagnetic torque formulas of the induction motor before and after the fault are constructed according to different transmission line and reactive power compensation device parameters before and after the fault, and the electromagnetic torque formula and the mechanical torque formula of the induction motor after the fault are simultaneously used to solve the unstable balance point of the inductor motor, so that the solution accuracy is improved, and the important basis forthe evaluation of the transient voltage stability of the induction motor load after the fault is provided. The method is important for guiding the actual power grid operation.

Description

Technical field [0001] The invention relates to a power system, and more specifically to a method for solving an unstable equilibrium point of an induction motor. Background technique [0002] In recent years, voltage stability problems have caused many blackouts. Therefore, voltage stability safety assessment has received more and more attention from operators and researchers, which puts forward higher requirements on the methods and results of voltage stability analysis. The induction motor load in the power system often accounts for more than 60%. After the system fails, the induction motor terminal voltage recovery process will absorb a large amount of reactive power from the grid, which aggravates the short-term reactive power shortage of the system and deteriorates the grid voltage stability. The dynamic characteristics of induction motor load is an important factor that affects the transient voltage stability of the power system, so how to reasonably and accurately analyze...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/16
CPCH02J3/16H02J2203/20Y02E40/30
Inventor 张文朝薛峰潘晓杰李锴潘艳徐友平邵德军张三洪党杰边宏宇
Owner CENT CHINA BRANCH OF STATE GRID CORP OF CHINA