Abstract
Partial discharge (PD) localization in substations based on the ultra-high frequency (UHF) method can be used to efficiently assess insulation conditions. Localization accuracy is affected by the accuracy of the time delay (TD) estimation, which is critical for PD localization in substations. A review of existing TD estimation methods indicates that there is a need to develop methods that are both accurate and computationally efficient. In this paper, a novel TD estimation method is proposed to improve both accuracy and efficiency. The TD is calculated using an improved cross-correlation algorithm based on full-wavefronts of array UHF signals, which are extracted using the minimum cumulative energy method and zero-crossing points searching methods. The cross-correlation algorithm effectively suppresses the TD error caused by differences between full-wavefronts. To verify the method, a simulated PD source test in a laboratory and a field test in a 220 kV substation were carried out. The results show that the proposed method is accurate even in case of low signal-to-noise ratio, but with greatly improved computational efficiency.
Highlights
The early faults of high-voltage equipment in substations can be detected effectively by locating the partial discharge (PD) source based on the ultra-high frequency (UHF) method [1]
The key of the time difference of arrival (TDOA) method is to calculate the time delay (TD) between any two UHF signals captured by the sensor array
In [16], a TD estimation method using the cross-correlation algorithm based on a half-wavefront was proposed, which was used to locate the PD source in air-insulated substations
Summary
The early faults of high-voltage equipment in substations can be detected effectively by locating the partial discharge (PD) source based on the ultra-high frequency (UHF) method [1]. The consistency of the UHF array signals is severely reduced by the multipath effect [10,11], which affects the accuracy of the cross-correlation algorithm [12]; this algorithm has certain advantages when the SNR is low. The high energy component of the captured UHF signal is dominated by the field noise when the SNR is low, and the onset time cannot be obtained with reasonable accuracy. In [16], a TD estimation method using the cross-correlation algorithm based on a half-wavefront was proposed, which was used to locate the PD source in air-insulated substations. To resolve the influence of non-Gaussian noise on the cross-correlation algorithm, a method based on high-order statistics was proposed in [12] This method effectively mitigates the effect of field noise. TD Estimation Method by Using Improved Cross-Correlation Algorithm Based on FullWavefronts of UHF Signals
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