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Voltage sag source identification method based on Mamdani fuzzy reasoning

A voltage sag source and identification method technology, which is applied in the direction of reasoning methods, electrical components, circuit devices, etc., can solve problems such as misjudgment of voltage sag source identification methods, and achieve the effect of reducing identification errors and improving accuracy

Inactive Publication Date: 2009-11-04
STATE GRID TIANJIN ELECTRIC POWER +1
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Problems solved by technology

[0010] The purpose of the present invention is to propose a voltage sag source identification method based on Mamdani fuzzy reasoning to improve the accuracy of voltage sag source identification in view of the problem of misjudgment in the currently used voltage sag source identification method

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  • Voltage sag source identification method based on Mamdani fuzzy reasoning
  • Voltage sag source identification method based on Mamdani fuzzy reasoning
  • Voltage sag source identification method based on Mamdani fuzzy reasoning

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Embodiment Construction

[0031] The preferred embodiments will be described in detail below in conjunction with the accompanying drawings. It should be emphasized that the following description is only exemplary and not intended to limit the scope of the invention and its application.

[0032] The main causes of voltage sags are short-circuit faults, transformer switching and induction motor starting. The present invention realizes the identification of the above three voltage sag causes. Through experimental research, the following conclusions are obtained:

[0033]The voltage sag caused by a short-circuit fault has the following characteristics: 1. The duration of the sag is determined by the fault removal time; 2. When the sag occurs and ends, the voltage will change suddenly, and the voltage between the mutation points basically does not change; 3. Symmetrical faults The voltage sag caused by the three-phase voltage is balanced, and the three-phase voltage sag caused by the asymmetrical fault is...

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Abstract

The invention discloses a voltage sag source identification method based on Mamdani fuzzy reasoning, belonging to technical field of voltage quality monitoring of a power system. The method comprises the steps of calculating the membership degree of three-phase voltage to balance, the membership degree of the voltage at the end of voltage sag to mutation degree and the membership degree to harmonic content; inputting the membership degrees to an Mamdani fuzzy reasoning system and substituting into fuzzy rules to calculate a corresponding fuzzy result; and using the center of gravity defuzzification for defuzzifying the fuzzy result to obtain the type of a sag source. The method takes into account of inherent differences of four different sag causes and is started from amplitude, mutation and harmonic, thereby avoiding the impacts of a plurality of uncertain features on the analysis accuracy of different sag sources; in addition, the method fuzzifies the input and the output quantities of the reasoning system, thereby avoiding the practice that the prior art needs to determine thresholds of all the feature values and further reducing the identification errors caused by the fixation of the thresholds.

Description

technical field [0001] The invention belongs to the technical field of power system voltage quality monitoring, and in particular relates to a voltage sag source identification method based on Mamdani fuzzy reasoning. Background technique [0002] Voltage sag refers to an event in which the root mean square value of the supply voltage suddenly drops to 90% to 1% of the rated value in a short period of time, and its typical duration is 0.5 to 30 cycles. Its amplitude is generally defined as the ratio of the root mean square value of the voltage during the sag to the root mean square value of the rated voltage, and the duration is the time between the occurrence and the end of the sag. At the same time, the voltage sag is often accompanied by a sudden change in the voltage phase, that is, a phase jump. The amplitude, duration and phase jump of the voltage sag are the three most important characteristic quantities of the nominal voltage sag. [0003] Voltage sag is not a new ...

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Application Information

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IPC IPC(8): H02J3/00G06N5/04
CPCY04S10/54
Inventor 李国栋郭浩李晓辉丁宁徐永海
Owner STATE GRID TIANJIN ELECTRIC POWER
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