CN-122021194-A - Transformer insulation paper machine-thermal coupling aging and service life prediction method and system

CN122021194ACN 122021194 ACN122021194 ACN 122021194ACN-122021194-A

Abstract

The invention provides a transformer insulation paper machine-thermal coupling aging and service life prediction method and system, which belong to the technical field of power transformer insulation state evaluation and service life prediction, and comprise the steps of obtaining temperature data and winding load current data in the actual operation process of a transformer; the method comprises the steps of constructing a machine-thermal coupling ageing model based on an insulating paper thermal ageing model and a mechanical ageing model, inputting an insulating paper initial state parameter and a discrete working condition sequence into the machine-thermal coupling ageing model, calculating the degree of aggregation of the insulating paper at the current moment, calculating the increment of fatigue damage and updating the accumulated degree of fatigue damage on the basis, judging according to the established double failure criteria, judging that the insulating paper fails when the degree of aggregation of the insulating paper is reduced to the critical degree of aggregation or the accumulated degree of fatigue damage reaches a limit value, and finally outputting the predicted service life of the insulating paper under the machine-thermal coupling effect and an evolution curve of the degree of aggregation of the insulating paper and the accumulated degree of fatigue damage so as to intuitively reflect the ageing process of the insulating paper.

Inventors

LIU HONGSHUN
WANG YUQING
SHEN YANG
CHEN XI
LIU JIALI
LI QINGQUAN
WU HONGBIN
HE DONGXIN
FENG JINGTONG
REN FUQIANG
LIU LUYAO
MENG FANBO

Assignees

山东大学

Dates

Publication Date: 20260512
Application Date: 20260410

Claims (10)

1. A transformer insulation paper machine-thermal coupling aging and service life prediction method is characterized by comprising the following steps: acquiring temperature data and winding load current data in the actual running process of the transformer, calculating equivalent vibration stress amplitude born by the insulating paper based on the load current data, and generating a vibration stress time sequence corresponding to the temperature time sequence to obtain a discrete working condition sequence on the same time axis; Respectively constructing an insulating paper thermal ageing model and a mechanical ageing model, and constructing a machine-thermal coupling ageing model based on the insulating paper thermal ageing model and the mechanical ageing model; establishing a double failure criterion based on polymerization degree degradation and fatigue damage accumulation; inputting the initial state parameters of the insulating paper and the discrete working condition sequence into the machine-thermal coupling aging model, and gradually calculating the polymerization degree of the insulating paper in each time step by adopting a numerical iteration method of fixed-step time dispersion; Based on the polymerization degree of the insulating paper in the current time step, dynamically correcting the mechanical fatigue life, calculating the fatigue life under the corresponding stress condition, further calculating the fatigue damage increment, and further updating the accumulated fatigue damage degree; Judging according to the double failure criteria in each time step, and judging that the insulating paper fails when the polymerization degree of the insulating paper is reduced to the critical polymerization degree or the accumulated fatigue damage degree reaches a limit value; Outputting the predicted service life of the insulating paper under the mechanical-thermal coupling effect and the evolution curve of the polymerization degree and the accumulated fatigue damage degree of the insulating paper so as to intuitively reflect the aging process of the insulating paper.
2. The transformer insulation paper machine-thermal coupling aging and service life prediction method as claimed in claim 1, wherein when the equivalent vibration stress amplitude born by the insulation paper is calculated based on load current data, a mechanical stress equivalent coefficient K σ is introduced, and a mapping relation between the load current data and the equivalent vibration stress amplitude is established: wherein σ (t k ) represents the equivalent vibration stress amplitude born by the insulating paper layer in the time step t k , and I (t k ) is the corresponding load current data.
3. The method for predicting aging and life of insulation paper machine-thermal coupling of transformer according to claim 2, wherein the mechanical stress equivalent coefficient is determined by establishing a structural dynamics model of the winding structure of the transformer, specifically: and establishing a finite element model of a typical structure of the transformer winding, which comprises a winding conductor, an insulating paper layer, a compression structure and a winding supporting structure, obtaining the stress intensity of the maximum displacement position of the winding center when different current excitation is applied through simulation calculation, and obtaining the value of a mechanical stress equivalent coefficient K σ through fitting a plurality of groups of data.
4. The method for predicting the aging and life of a transformer insulation paper machine-thermal coupling of claim 1, wherein the method for constructing the insulation paper thermal aging model and the mechanical aging model comprises the following steps: Respectively establishing a thermal aging model of the insulating paper and a mechanical aging model of the insulating paper; The cellulose random degradation dynamics equation is used as a thermal aging basic model of the insulating paper, And describing the relation between the vibration stress amplitude and the mechanical fatigue life by adopting Basquin equation, and establishing a mechanical aging model of the insulating paper by combining with Miner linear fatigue accumulation damage criterion.
5. The method for predicting the machine-thermal coupling aging and service life of a transformer insulation paper according to claim 1, wherein when constructing the machine-thermal coupling aging model based on the insulation paper thermal aging model and the mechanical aging model, the method comprises the following steps: Establishing a functional association relation between a fatigue strength coefficient in Basquin equation and the real-time polymerization degree DP (t) of the insulating paper as a correction equation so as to realize dynamic correction of the thermal aging state on the mechanical fatigue life; substituting the correction equation into Basquin equation to obtain fatigue life equation after real-time correction of thermal aging; And (3) introducing a mechanical stress correction term, and correcting an Arrhenius thermal reaction rate model in the thermal aging model to represent the acceleration effect of mechanical vibration stress on the thermal degradation process, so as to obtain a thermal degradation reaction rate constant under the condition of mechanical-thermal coupling.
6. The method for predicting aging and life of insulation paper machine-thermal coupling of transformer according to claim 1, wherein a double failure criterion is adopted, namely, when any one of the following conditions is satisfied, the insulation paper is considered to reach a failure state: (1) The polymerization degree of the insulating paper is reduced to the critical polymerization degree; (2) The cumulative fatigue damage reaches a limit value.
7. A transformer insulation paper machine-thermal coupling aging and life prediction system, comprising: The discrete working condition sequence generation module is configured to acquire temperature data and winding load current data in the actual operation process of the transformer, calculate equivalent vibration stress amplitude born by the insulating paper based on the load current data, and generate a vibration stress time sequence corresponding to the temperature time sequence so as to acquire a discrete working condition sequence on the same time axis; The model construction module is configured to respectively construct an insulating paper thermal aging model and a mechanical aging model, construct a machine-thermal coupling aging model based on the thermal aging model and the mechanical aging model, and establish a double-failure criterion based on polymerization degree degradation and fatigue damage accumulation; The prediction calculation module is configured to carry out numerical iterative calculation based on the machine-thermal coupling aging model and update the polymerization degree and the accumulated fatigue damage degree of the insulating paper; A failure determination module configured to determine an insulation paper failure state based on the double failure criterion, and determine that the insulation paper fails when the degree of polymerization of the insulation paper falls to a critical degree of polymerization or the cumulative fatigue damage reaches a limit value; and the result output module is configured to output the predicted service life of the insulating paper under the mechanical-thermal coupling effect and the evolution curve of the polymerization degree and the accumulated fatigue damage degree of the insulating paper so as to intuitively reflect the aging process of the insulating paper.
8. A computer program product comprising a computer program, characterized in that the computer program, when executed by a processor, implements the method of any one of claims 1 to 6.
9. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the steps of the method of any of the preceding claims 1-6 when the program is executed.
10. A computer readable storage medium, on which a computer program is stored, characterized in that the program, when being executed by a processor, performs the steps of the method of any of the preceding claims 1-6.

Description

Transformer insulation paper machine-thermal coupling aging and service life prediction method and system Technical Field The invention belongs to the technical field of power transformer insulation state evaluation and life prediction, and particularly relates to a transformer insulation paper machine-thermal coupling aging and life prediction method and system. Background The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art. In the long-term operation process of the oil-immersed power transformer, the insulating paper can be subjected to the combined action of various factors such as temperature, electric field, mechanical force, moisture, oxygen and the like. Among them, temperature is generally considered to be the most dominant factor affecting the aging of insulating paper. The high temperature environment accelerates the breaking and degradation reaction of cellulose molecular chains, so that the polymerization degree of the insulating paper is gradually reduced, and the mechanical strength and dielectric property of the material are reduced. Meanwhile, under the actual running condition, the transformer winding can generate continuous vibration under the action of electromagnetic force, leakage magnetic field and magnetostriction effect, so that the winding insulation structure can bear the periodic alternating mechanical stress effect for a long time. Particularly, under special operation conditions such as a converter transformer, the vibration amplitude of the winding is obviously increased due to the existence of a direct current magnetic bias phenomenon, so that the influence of mechanical stress on the ageing process of the insulating paper is aggravated. The existing researches focus on the influence of factors such as temperature, electric field or humidity on the ageing behavior of the insulating paper, the researches on the ageing characteristics of the insulating paper under the action of mechanical stress are relatively few, and particularly, a mechanical-thermal coupling ageing model capable of reflecting the mutual influence of the ageing state change of the material and the mechanical vibration stress damage is lacking, so that the insulating state evaluation and the service life prediction of the power transformer in the prior art are inaccurate. Disclosure of Invention In order to overcome the defects in the prior art, the invention provides a transformer insulation paper machine-thermal coupling aging and service life prediction method and system. Aiming at the aging behavior of the insulating paper under the combined action of mechanical vibration stress and thermal stress, a corresponding coupling aging evaluation method is constructed. Through establishing the bidirectional coupling relation between thermal ageing and mechanical vibration, the thermal ageing state of the insulating paper can dynamically influence the mechanical fatigue strength, and meanwhile, the mechanical vibration can reversely change the thermal degradation reaction rate, so that the oil paper insulation degradation process under the actual running environment of the transformer is reflected more truly, and the service life of the insulating paper and the insulation state of the transformer are estimated more accurately. To achieve the above object, one or more embodiments of the present invention provide the following technical solutions: in a first aspect, a transformer insulation paper machine-thermal coupling aging and life prediction method is disclosed, comprising: acquiring temperature data and winding load current data in the actual running process of the transformer, calculating equivalent vibration stress amplitude born by the insulating paper based on the load current data, and generating a vibration stress time sequence corresponding to the temperature time sequence to obtain a discrete working condition sequence on the same time axis; respectively constructing an insulating paper thermal ageing model and a mechanical ageing model, and constructing a machine-thermal coupling ageing model based on the thermal ageing model and the mechanical ageing model; establishing a double failure criterion based on polymerization degree degradation and fatigue damage accumulation; inputting the initial state parameters of the insulating paper and the discrete working condition sequence into the machine-thermal coupling aging model, and gradually calculating the polymerization degree of the insulating paper in each time step by adopting a numerical iteration method of fixed-step time dispersion; Based on the polymerization degree of the insulating paper in the current time step, dynamically correcting the mechanical fatigue life, calculating the fatigue life under the corresponding stress condition, further calculating the fatigue damage increment, and further updating the accumulated fatigue damage degree; Judging a