State Evaluation Method of Power Transformer Windings Based on System Delay Order Estimation

Abstract

The present invention discloses a power transformer winding state assessment method based on improved system delay order estimation. The method better reflects the winding mechanical structure state based on the winding vibration generation mechanism to directly associate winding faults with a characteristic quantity so as to provided basis for effectiveness and scientificity of fault diagnosis. Compared to prior to improvement, the extracted characteristic quantity is closer to the actual orders of the system so as to more accurately reflect the system characteristics and the winding mechanical structures. Besides, the concrete achievement has no any electrical connection with the transformer, outage of the transformer does not need so as to have little influence for the operation of thewhole electric system.

Description

technical field [0001] The invention belongs to the technical field of power transformer safety fault detection, and in particular relates to a power transformer winding state evaluation method based on an improved system delay order estimation. Background technique [0002] As a very important part of the power system, large power transformers play an important role in ensuring the safe and reliable power supply of the power grid. In power transformer faults, the proportion of winding faults is as high as 46.4%, which is the most important part of transformer faults, and the serious faults caused by mechanical deformation of windings under the action of electrodynamic force account for 70% of the total faults of windings. Even a slight deformation of the winding will cause deterioration of the mechanical properties of the winding, reduction of insulation strength and short-circuit resistance, and other problems, which will bring great safety hazards. Therefore, it is very ...

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Problems solved by technology

[0004] The Chinese patent with the application number 201310047702.0 proposes a power transformer fault diagnosis method based on the electric-vibration model, which establishes the vibration frequency components by collecting the voltage signal, current signal, oil temperature signal and multiple vibration measuring points of the transformer. and the regression model between current, voltage and oil temperature, and compare the measured data of vibration with the predicted data obtained through the model to diagnose the fault of the transformer; although this method considers the nonlinearity in the vibration of the transformer to a certain extent, However, there are still some problems that some frequency components introduced by strong nonlinearity such as hysteresis effect cannot be modeled or the model error is large, so this method still has certain limitations in accuracy and effectiveness.

[0005] The Chinese patent with the application number 201710867458.0 proposes and constructs a Hammerstein nonlinear model between current and winding vibration based on the principle of transformer winding vibration, and extracts the system characteristics of the model - the system delay order, reflecting the transformer winding The state of the mechanical structure; this method takes into account the physical mechanism of the influence of mechanical faults on the characteristics of the model system, and only extracts part of the fault-related information in the model as a basis for diagnosis, which can effectively avoid misjudgments directly caused by model errors. When the delay order extraction algorithm has a large difference between the input and output orders of the system, there will be a problem of large estimation error or even wrong estimation, which will affect the accuracy of the winding state evaluation results

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