scholarly journals An Accurate and Efficient Time Delay Estimation Method of Ultra-High Frequency Signals for Partial Discharge Localization in Substations

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3439 ◽  
Author(s):  
Pengfei Li ◽  
Kejie Dai ◽  
Tong Zhang ◽  
Yantao Jin ◽  
Yushun Liu ◽  
...  
Keyword(s):  
Time Delay ◽  
High Frequency ◽  
Cross Correlation ◽  
Partial Discharge ◽  
Estimation Method ◽  
Time Delay Estimation ◽  
Estimation Methods ◽  
Zero Crossing ◽  
Ultra High Frequency ◽  
Correlation Algorithm

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.

Experimental Comparison of GCC-Based Time Delay Estimation Methods for Ultrasonic Leak Detection in Compressed Air System

2012 ◽  
Author(s):  
Pingping Liao ◽  
Maolin Cai ◽  
Xiangheng Fu
Keyword(s):  
Standard Deviation ◽  
Time Delay ◽  
Cross Correlation ◽  
Leak Detection ◽  
Time Delay Estimation ◽  
Compressed Air ◽  
Delay Estimation ◽  
Estimation Methods ◽  
Experimental Comparison ◽  
Success Rates

Air leakage is one of the most significant energy waste factors in compressed air systems which account for about 10% of total industrial energy consumption. It is estimated that about 10%∼40% of the compressed air is wasted through leakage in most plants. A new ultrasonic leak detection method based on time delay estimation (TDE) is proposed to locate the compressed air leak for preventing energy waste in pneumatic systems. The accuracy of detection is highly dependent on the performance of the TDE method. Performances of six typical TDE methods based on generalized cross correlation (GCC) are compared, and these methods are the basic cross correlation (BCC), the Roth impulse response, the phase transform (PHAT), the smoothed coherence transform (SCOT), the WEINER processor, and the Hannan-Thomson (HT) processor. The experimental results show that: Firstly, the accuracy and precision of time delay estimation increases with the observation interval for all these methods. Secondly, the success rates of Roth, PHAT, SCOT and HT are much higher than that of BCC and WEINER, among which the HT processor performs best with a highest success rates closely followed by the PHAT processor. Thirdly, the HT processor which is a maximum likelihood estimator gives the minimum standard deviation of the time delay estimate; however, the standard deviations of all these GCC methods are very small. The HT processor outperforms other GCC methods in terms of success rate and standard deviation. Consequently, it is preferable to apply the HT processor for this particular purpose.

The Performance Correlation Hilbert Time-Delay Estimation for Passive Detection

2014 ◽  
Vol 602-605 ◽  
pp. 1768-1771
Author(s):  
Feng Wang ◽  
Mei Quan Liu ◽  
Jiang Wei Fan
Keyword(s):  
Time Delay ◽  
High Speed ◽  
Time Lag ◽  
Estimation Method ◽  
Time Delay Estimation ◽  
Time Difference ◽  
Delay Estimation ◽  
Main Peak ◽  
Zero Crossing ◽  
Passive Detection

Passive time difference detection method is distance, high speed and good concealment which has broad military application prospects. One of the key technologies for passive detection is to extract the time lag through effective signal processing. Relevant method is the most basic method to estimate the time difference and is the basic theory of all correlative time-delay estimation algorithms. The method is simple. But good results rely on the spectrum characteristics of signal and noise is ideal. Time delay estimation based on Hilbert transform is the expansion of the generalized correlation time-delay estimation method which changes the correlation function from accidentally symmetry into odd symmetry. Detecting correlation peak is converted into zero crossing detection. The method sharps the main peak value point and improved the precision of time delay estimation which gets better time-delay estimation performance in the narrowband signal.

A Height Estimation Method Based on Joint Time Delay and Phase Estimation for Wideband InSAR or InSAS

2012 ◽  
Vol 605-607 ◽  
pp. 1105-1109
Author(s):  
Sen Zhang ◽  
Jin Song Tang ◽  
He Ping Zhong
Keyword(s):  
Time Delay ◽  
Cross Correlation ◽  
Estimation Method ◽  
Simulated Data ◽  
Time Delay Estimation ◽  
Phase Estimation ◽  
Height Estimation ◽  
Common Information ◽  
Correlation Estimation ◽  
Better Than

In this paper, a new height estimation method based on joint time delay and phase estimation is proposed, which can solve the contradiction between the dimensions of the observing space and the hypothesis of spatial stationarity. It can improve the performance and robustness of time delay estimation by utilizing the neighboring pixels’ common information though spatial processing. The simulated data varifies the perfermance of the proposed method. The result is that its performance is better than the cross correlation estimation method.

A Novel Scheme for Time Delay Estimation in the Fractional Fourier Transform Domain

2013 ◽  
Vol 385-386 ◽  
pp. 1425-1428
Author(s):  
Xue Mei Li
Keyword(s):  
Time Delay ◽  
Fractional Fourier Transform ◽  
Estimation Method ◽  
Time Delay Estimation ◽  
Delay Estimation ◽  
Estimation Methods ◽  
Fourier Domain ◽  
Transform Domain ◽  
Chirp Signal ◽  
Fourier Transform Domain

A time delay estimator based on the fractional bispectrum is proposed; and it is suitable for the chirp signal. The proposed time delay estimation technique can outperform the conventional time delay estimation methods associated with the bispectrum in the Fourier domain under the correlated Gaussian noises at lower SNR. Simulation results demonstrate the validity of this estimation method.

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