Research on NOFRF Entropy-Based Detection Method for Early Damage of Pillar Porcelain Insulator

Abstract

<jats:p>The pillar porcelain insulator is an important protection device that is related to the safety of the entire power grid. Small damage of it may even cause a disaster. Nonlinear output frequency response functions (NOFRFs) can well reflect the nonlinear characteristics of early damage in the system. This paper uses the NOFRF entropy-based harmonic excitation detection method to detect the damage of the structure. Its effect has been verified by using metal specimens. Then, the pulse hammer detection and harmonic detection are carried out to detect the early-stage damage of the pillar porcelain insulator, and they achieve a good result, which verifies that the harmonic detection method can detect the early-stage damage in the pillar porcelain insulator as well. In addition, the orthogonal test of the simulated breathing crack model is used to search the greatest influence of the parameters of crack on the detection index. Through the orthogonal analysis, the results show that among the lengths, positions, and angles of the crack, the length of crack is the main factor that affects the detection index.</jats:p>

A quantitative feature extraction method for rotor shaft misalignment based on WNOFRFs

“…Based on the NOFRFs-associated index, Liu [20][21][22] integrated the concepts of feature weighting and contribution rate and developed the NOFRFs weighted contribution rate (WNOFRFs)…”

“…To measure the differences in NOFRFs between damaged systems and healthy systems, some literature has focused on NOFRFs-associated indexes to represent changes in system nonlinear characteristics [18][19][20][21][22][23][24][25][26]. Peng [18] first proposed the concept of NOFRFs-associated indexes.…”

“…Fatigue damage experiments demonstrate Ne can describe the degree of fatigue damage quantitatively and is more sensitive. To construct a more sensitive index, Mao [20] introduced the information entropy theory to NOFRFs and proposed NE for crack damage detection and verified through experiments of the pillar porcelain insulator. By introducing the concept of information entropy, complexity and divergence, Mao [21,22] also constructed NOFRFs frequency domain complexity entropy index IFEn, non-linear scale index NL, NOFRFs divergence index NDI and NOFRFs-KL (NKL), which are more sensitive and more intuitive than Fe in fatigue damage experiments.…”

A laser-induced dual ultrasonic wave method for noncontact load monitoring of pillar porcelain insulators

“…Pillar porcelain insulators are prone to large stress concentrations due to installation errors, harsh environments, improper operation, and other factors during application [3,4]. Moreover, cracks, pores, and other defects will inevitably occur in the production process [5,6]. Local stress concentration will lead to the continuous expansion of the defects and sudden fracture of the brittle insulator [7].…”