Metal Contamination Distribution Detection in High-Voltage Transmission Line Insulators by Laser-induced Breakdown Spectroscopy (LIBS).

Naixiao Wang,Ping Chen,Qishen Lv,Ronghui Huang,Xilin Wang,Liming Wang,Zhidong Jia

doi:10.3390/s18082623

Abstract

The fast detection of classical contaminants and their distribution on high-voltage transmission line insulators is essential for ensuring the safe operation of the power grid. The analysis of existing insulator contamination has traditionally relied on taking samples during a power cut, taking the samples back to the lab and then testing them with elemental analysis equipment, especially for sugars, bird droppings, and heavy metal particulates, which cannot be analysed by the equivalent salt deposit density (ESDD) or non-soluble deposit density (NSDD) methods. In this study, a novel method called laser-induced breakdown spectroscopy (LIBS) offering the advantages of no sample preparation, being nearly nondestructive and having a fast speed was applied for the analysis of metal contamination. Several LIBS parameters (laser energy and delay time) were optimized to obtain better resolution of the spectral data. The limit of detection (LOD) of the observed elements was obtained using a calibration curve. Compared to calibration curves, multivariate analysis methods including principal component analysis (PCA), k-means and partial least squares regression (PLSR) showed their superiority in analyzing metal contamination in insulators. Then, the elemental distribution of natural pollution was predicted using LIBS to fully capture information about the bulk elements (Na, Ni, Cu, Mn, Ca, etc.) of entire areas with PLSR. The results showed that LIBS could be a promising method for accurate direct online quantification of metal contamination in insulators.

Highlights

Transmission line insulators are often contaminated with dust, bird droppings, soluble salts and metal particulates from Nature or surrounding factories
Measurement parameters were optimized with respect to the spectral intensity and relative standard (RSD) of measured elements
Calibration curves were obtained between the concentration and intensity, and the limit of detection (LOD) of the observed elements was calculated

Summary

Introduction

Transmission line insulators are often contaminated with dust, bird droppings, soluble salts and metal particulates from Nature or surrounding factories. Pollution flashover more occurs, causing large-scale power cuts under wet conditions [1,2,3,4]. Are more likely to attract electrically conductive metal particles, such as Cu, Mn, Ni, etc., which even in micro amounts may cause power frequency flashover accidents [5]. Serious partial discharge activity and flashovers on insulator strings occurred in 2010 and 2013 at the Ningxia Fuxiang 220 kV substation in China. Surrounding this were densely distributed thermal power plants, cement plants, chemical plants, etc. A variety of Na, Mg, Al, Fe, Mn, Zn, C, CaSO4 and Sensors 2018, 18, 2623; doi:10.3390/s18082623 www.mdpi.com/journal/sensors

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Results

Conclusion