Abstract
Direct lightning strokes account for a large proportion of line faults. Lightning faults can be classified into several kinds, and the corresponding protection methods differ. The type of these lightning faults should be identified to establish targeted measures against lightning and improve lightning protection design. In this study, a non-contact multi-physical parameter lightning monitoring system is proposed. The voltage of the insulator string and the lightning grounding current of the transmission tower are chosen as two physical parameters to show the characteristic quantities of different lightning stroke types. These physical parameters are captured using a non-contact overvoltage sensor installed at the cross arm of the tower and several parallel Rogowski coils installed at the tower ground supports. An equivalent electromagnetic transient model of a 110 kV transmission line is developed to identify features of the signals under different lightning strokes. Based on time-domain and wavelet transform modulus maxima (WTMM) analyses, the polarity of insulator voltage, the polarity of tower current, and the mutation polarity of tower current when insulators flashover are extracted as characteristic quantities of polarity discrimination. Six kinds of direct lightning strokes can be identified based on the polarity discrimination method considering the lightning stroke point and the lightning current polarity. The identification method is verified by simulation data and application to an actual example.
Highlights
Power transmission lines are an important part of a power system
This study proposes a non-contact multi-physical parameter acquisition method to identify different lightning stroke faults
According to the analysis explained in the preceding paragraphs, when the negative lightning stroke happens, the following features can be obtained: stroke happens, the following features can be obtained: (1) When lightning strokes to the top of the tower, Uins > 0 and Ig > 0; when lightning strokes to the phase conductor, Uins < 0 and Ig > 0
Summary
Power transmission lines are an important part of a power system. Operating experience and statistical data show that direct strokes account for a large proportion of line faults [1,2,3,4]. Enhancing lightning protection for power transmission lines is highly significant for the safety and stability of a power system. Direct strokes can be classified into two kinds, namely, shielding failure and back flashover. These stroke faults have distinct mechanisms, development rules, and waveform characteristics. Different protection methods should be used according to the type of the lightning stroke fault. These stroke faults should be identified to efficiently adopt targeted measures against lightning and improve lightning protection design [5,6,7,8,9,10]
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