A Phase Identification Method and Device Based on Hilbert-Huang Transform and Expert System

Abstract

The invention discloses a phase discrimination method and device based on Hibert-Huang transform and an expert system. The method includes: performing empirical mode decomposition on to-be-detected voltage signals, and adopting Hibert-Huang transform to acquire instantaneous amplitude, phase and frequency of a decomposed intrinsic mode function so as to determine fundamental wave instantaneous phase of the to-be-detected voltage signals; in order to realize automatic phase discrimination, building the expert system to autonomously analyze detected phase difference so as to determine phase sequence phase relation of the to-be-detected voltage signals. By the phase discrimination method and device, phase checking accuracy and phase checking efficiency can be improved remarkably, workload of on-site working personnel can be reduced, and intelligent level of a power grid can be elevated.

Description

technical field [0001] The invention relates to a phase identification method and device based on Hilbert-Huang transformation and an expert system, and belongs to the technical field of electrical engineering. Background technique [0002] Before the new power plant is connected to the grid, before the new substation is put into operation, after the expansion, transformation or major equipment overhaul of the power transmission and transformation project, the phase verification test is often done on the completion and commissioning site, including phase sequence verification and phase verification. Incorrect phase sequence will result in serious accidents such as the failure of the generator to be connected to the grid and the reverse rotation of the motor, resulting in huge loss of life and property. Phase is one of the three elements of periodic signal, its accurate detection is of great significance for phase nuclear work. [0003] At present, the commonly used phase de...

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Problems solved by technology

The disadvantage of the zero-crossing detection method is that when the frequency of the measured signal fluctuates, the accuracy is low, the error is large, and it is not suitable for the phase detection of the power signal; The accuracy is low; the most commonly used in the instantaneous value method is the discrete Fourier transform (DFT). This algorithm is convenient to implement and does not require rectification and filtering. The influence will lead to large errors, and it does not have time-domain resolution, and cannot reflect the change of the instantaneous frequency of the signal over time, so it is only suitable for analyzing stationary signals

[0004] At this stage, most of the nuclear phase work adopts the coordination and cooperation of multiple people, multiple measurements, and manual comparison of voltages, which has a large workload and low efficiency

Moreover, when a problem is found in the nuclear phase, it is often necessary for the tester to analyze and judge based on his own experience, which not only potentially increases the work intensity of the staff, reduces the work efficiency, but also requires a high level of skill for the staff. It is also more difficult and there is a potential risk of error

[0005] Through the above analysis, it can be found that the existing nuclear phase methods and devices have poor precision, low efficiency, and are not intelligent enough

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