On the Feasibility of Gap Detection of Power Transformer Partial Discharge UHF Signals: Gap Propagation Characteristics of Electromagnetic Waves
Abstract
:1. Introduction
2. Propagation Characteristics of Electromagnetic Waves in Gaps
2.1. Edge Diffraction
2.2. Kirchhoff Diffraction Theory
2.3. Propagation of Electromagnetic Waves in Transformer
3. Simulation Experiment
3.1. Simulation Model
3.2. Analysis of Simulation Results
3.2.1. Propagation Characteristics in the Transformer Gap of the Electromagnetic Waves Radiated by the PD Source in Different Directions
3.2.2. Influence of Gap Height on Gap Propagation Characteristics of the PD Electromagnetic Waves
3.2.3. Influence of Gap Depth on Gap Propagation Characteristics of the PD Electromagnetic Waves
4. Comparison with Experiment
4.1. Experimental Scheme
- (1)
- When the transformer gap is 3 cm high and 5 cm deep, the PD source is adjusted to X-, Y-, and Z-axis positive directions separately (refer to the coordinate system in the simulation experiment) to study the transformer gap propagation characteristics of electromagnetic signals radiated by PD source in different directions.
- (2)
- When the transformer gap is 5 cm deep and the PD source is oriented in Z-axis positive direction (refer to the coordinate system in the simulation experiment), the gap height is set to be 4, 3, and 2 cm separately to study the influence of gap height on the gap propagation characteristics of the electromagnetic wave.
- (3)
- When the transformer gap is 2 cm high and the PD source is oriented in Z-axis positive direction (refer to the coordinate system in the simulation experiment), the gap depth is set to be 18, 14, 10, and 6 cm separately to study the influence of gap depth on the gap propagation characteristics of electromagnetic wave.
4.2. Analysis of Experimental Results
- (1)
- When the transformer gap is 3 cm high and 5 cm deep, Figure 16 shows the layout of detection points in the experiment, where detection point Nos. 1–2 are located in the gap and the distance between the adjacent detection points is 2 cm. Detection point No. 3 is located in the transformer internal, and the distance from the tank wall is 2 cm. Detection point Nos. 4–6 are located in the transformer exterior, and the distance between adjacent detection points is 2 cm.
- (2)
- (3)
- On the basis of ensuring the operability of the experiment, the gap height is set to be 2 cm, the partial discharge source is oriented in Z-axis positive direction, the gap depths are 18, 14, 10, and 6 cm separately, and the electromagnetic wave signals are obtained according to the detection point layout in Figure 19. Figure 20 depicts the experimental results.
5. Conclusions
- (1)
- The intensity of the PD electromagnetic wave inside the gap is significantly greater than that in the transformer exterior. Therefore, in the gap detection of transformer PD electromagnetic wave signals, inserting the antenna sensor into transformer gap will considerably improve the detection sensitivity.
- (2)
- Inside the gap, the difference of electromagnetic wave intensity radiated by PD source in different directions is significantly large. Therefore, each of the four gaps of transformer is required to be set with an antenna sensor to achieve full range and a high-sensitivity detection of the electromagnetic wave.
- (3)
- The gap height will affect the propagation of electromagnetic wave in the transformer gap. In the reasonable range of the gap height of the transformer, the intensity of the electromagnetic wave shows an increasing trend inside the gap with the decrease of gap height.
- (4)
- Inside the gap, the intensity of the electromagnetic wave shows a gradually increasing trend with the decrease of gap depth. Moreover, the intensity of electromagnetic wave has an increasing trend at the tail of gap. The antenna sensor should be placed in the entrance or the tail area of transformer gap and try to avoid the middle and back sections of transformer gap as much as possible.
Acknowledgments
Author Contributions
Conflicts of Interest
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Zhang, X.; Zhang, G.; Li, Y.; Zhang, J.; Huang, R. On the Feasibility of Gap Detection of Power Transformer Partial Discharge UHF Signals: Gap Propagation Characteristics of Electromagnetic Waves. Energies 2017, 10, 1531. https://doi.org/10.3390/en10101531
Zhang X, Zhang G, Li Y, Zhang J, Huang R. On the Feasibility of Gap Detection of Power Transformer Partial Discharge UHF Signals: Gap Propagation Characteristics of Electromagnetic Waves. Energies. 2017; 10(10):1531. https://doi.org/10.3390/en10101531
Chicago/Turabian StyleZhang, Xiaoxing, Guozhi Zhang, Yalong Li, Jian Zhang, and Rui Huang. 2017. "On the Feasibility of Gap Detection of Power Transformer Partial Discharge UHF Signals: Gap Propagation Characteristics of Electromagnetic Waves" Energies 10, no. 10: 1531. https://doi.org/10.3390/en10101531