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Stability margin quick assessment method in asymmetrical fault condition

A stable margin and asymmetric technology, applied in the direction of AC network circuits, electrical components, circuit devices, etc., can solve problems such as huge amount of calculation, unsatisfactory control effect, poor pertinence of off-line decision-making analysis, etc., and achieve fast and accurate calculation good sex effect

Inactive Publication Date: 2019-04-12
NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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Problems solved by technology

However, the stability of the power system during operation is affected by many factors. Information such as faults, fault types, and fault locations cannot be obtained in advance. Situations where the control effect is not ideal

Method used

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  • Stability margin quick assessment method in asymmetrical fault condition
  • Stability margin quick assessment method in asymmetrical fault condition
  • Stability margin quick assessment method in asymmetrical fault condition

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Embodiment Construction

[0021] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0022] Depend on figure 1 The calculation flow chart shown is for calculation and analysis. Firstly, the additional impedance value in the case of asymmetrical short circuit is calculated according to the network structure. For a power system with N-buses, the m-buses are connected to loads only, and the n-buses are connected to generators. When a short-circuit fault occurs at point f on line r-j, line r-j is divided into two sections by fault point f, and the line impedance is as follows:

[0023] Z rf =α·z L (1),

[0024] Z fj =(1-α)·z L (2),

[0025] α represents the percentage of the distance from the fault location to the receiving end node to the total length of the line. z L Indicates the impedance of the line r-f. According to the line parameters, the node impedance matrix before the system fault is calculated as Z (s) , ...

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Abstract

The invention discloses an online stability analysis method, and aiming at solving the problem that the system transient stability online calculation is complex and low in speed, a method for piecewise linearization after power angle approximation polymerization is provided, and the stability margin of the system after a fault is calculated online. Firstly, the additional impedance of an asymmetric fault is calculated by means of a positive sequence equivalent rule; network simplification is completed under the condition that additional impedance is considered, and a network model is obtained,wherein all nodes except an internal potential node, of the network model are eliminated. On the basis, a relative acceleration equation of a multi-machine system is converted into an equivalent single-machine infinite high-power bus system equation form. By establishing a segmented linear model, an expression of a power angle of a generator and an analysis analytical expression of system stability margin are obtained. For the stability margin expression, the stability degree of the system can be quickly judged according to the calculated fault removal angle. The method has the technical effects that the calculation speed is high and the accuracy is high; and finally, the effectiveness of the method is verified through simulation.

Description

technical field [0001] The invention belongs to the technical field of electrical engineering, and in particular relates to an evaluation method for transient stability of a power system. Background technique [0002] The transient stability analysis of the power system has always been an important part of the research content of the power system. The good transient stability of the disturbed system is the key to the long-term operation of the power grid. With the gradual development of high-penetration distributed power generation technology, more and more new energy power generation is integrated into the power grid, and the impact of random fluctuations in power and load in the power grid is increasing. In grids, oscillations are more likely to occur and cause transient stability problems. Large-scale grid interconnection and the use of power electronic devices make the system run closer to the stable boundary, and the scope of the fault is wider. If the fault cannot be ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/00
CPCH02J3/00H02J2203/20
Inventor 刘九良王增平王彤
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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