A fuzzy comprehensive evaluation method for aging degree of a ZnO varistor

Abstract

The invention discloses a fuzzy comprehensive evaluation method for aging degree of a ZnO varistor. The method comprises collecting data of power loss change rate, space charge distribution change rate, grain boundary barrier height change rate and grain boundary capacitance change rate in aging process, classifying the collected data and establishing an initial data sample set; establishing an aging evaluation system, wherein the evaluation indexes include four characteristic parameters: power loss, space charge, grain boundary barrier and grain boundary capacitance; determining the comprehensive weights of each evaluation index by AHP; constructing the evaluation model to evaluate the aging degree and draw the evaluation conclusion. The fuzzy comprehensive evaluation method for aging degree of the ZnO varistor combines the macroscopic parameter power loss of ZnO varistor with the microscopic parameter space charge distribution, grain boundary barrier height and grain boundary capacitance, the aging state of ZnO varistor can be evaluated effectively, and the specific aging degree value can be given to show the aging degree intuitively.

Description

technical field [0001] The invention belongs to the technical field of aging evaluation of dielectric varistors, and in particular relates to a fuzzy comprehensive evaluation method for the aging degree of ZnO varistors. Background technique [0002] According to the statistics of power system blackout accidents, insulation problems account for 50-80% of the faults, and transient overvoltage is an important cause of insulation problems. In order to limit the transient overvoltage and improve the reliability of power transmission, the installation of lightning arresters is the main measure to limit the occurrence of overvoltage in the power transmission system. [0003] Zinc oxide (ZnO) varistor is a kind of varistor material with superior nonlinearity. It has large flow capacity, relatively low residual voltage, and basically no delay. Therefore, arresters composed of ZnO varistors are widely used in high-voltage DC In power transmission project. As one of the important eq...

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Problems solved by technology

[0004] Regarding the evaluation of the aging degree of ZnO varistors, the predecessors evaluated the aging degree of ZnO varistors by testing leakage current or power loss, capacitance change, etc., and mostly stayed at the level of macro parameters for analysis, and more stayed at the evaluation of macro parameters However, there are few evaluation methods for parameters at the micro level

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