Method for discriminating type of low frequency oscillation mechanism based on envelope fitting

Abstract

The invention discloses a method for discriminating the type of a low frequency oscillation mechanism based on envelope fitting. The technical scheme comprises the steps of: first, acquiring an envelope of a dominant oscillation mode curve through oscillation data to be analyzed; then, carrying out discrimination on the periodicity of the envelope, thereby coming into different fitting determinations according to discrimination results; and finally, realizing discrimination of negative damping free oscillation, zero damping free oscillation, positive damping resonance and zero damping resonance according to fitting results. Compared with a technical scheme in the prior art, the method disclosed by the invention utilizes WAMS measured data, makes full use of envelope characteristics of various types of low frequency oscillations after extracting dominant mode signals through a digital signal processing method, and discriminates the type of the low frequency oscillation in a mode of fitting, the discrimination process is clear, the discrimination is precise and reliable, and the discrimination speed is high, thereby well meeting requirements for discrimination of the type of the low frequency oscillation, and having good engineering application values.

Description

technical field [0001] The invention belongs to the field of electric power technology, and in particular relates to a low-frequency oscillation mechanism type discrimination method based on envelope fitting. Background technique [0002] In recent years, with the construction of the UHV power grid, the national power grid has become more closely connected, and the number of low-frequency oscillation events in the power system has increased, and its harm has increased, which has seriously threatened the safety and stability of the power grid and restricted the power transmission of the power grid. ability, resulting in huge economic losses. There are two main types of low-frequency oscillation mechanism: negative damping mechanism and forced resonance mechanism. The mechanism of low-frequency oscillation is different, and its manifestations and control measures are also different. How to quickly judge the type of oscillation through the complex low-frequency oscillation wa...

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Problems solved by technology

Liu Zenghuang, Jia Wenshuang, Li Ying, etc. used the straight line method (patent number: 201210397698.6) and the quadratic difference method (patent number: 201210103545.6), but this method cannot judge the beat frequency oscillation, which may be misjudged as negative damping oscillation

Ye Hua, Song Youbin, and Liu Yutian proposed a low-frequency oscillation type identification method based on the identification of response components and oscillation characteristics (Patent No.: 201210455272.1), using the Prony algorithm to identify the oscillation components and damping ratio, and then judging each Oscillation, but this method relies on the accuracy of the identification method and requires a long data segment, and the Prony method itself has certain limitations, so the identification results are often unsatisfactory for actual signals

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