Improved Electrogeometric Model Suitable for EHV and UHV Transmission Lines Developed through Breakdown Testing for Long Air Gaps
Abstract
:1. Introduction
2. Improvement of the Conventional Calculation
2.1. Influence of the Equation and the Correction Factor of the EGM
2.2. Modification of EGM Parameter
2.2.1. Influence of Wave Rise Time on the Modification for EGM Parameters
2.2.2. Modification of the EGM Equation
2.2.3. Modification of Correction Factor
3. Comparisons of Calculation Results and the Lightning Observation Results in Japan
3.1. Computation Flow Based on the Improved EGM
3.2. Analysis of Calculation Results and Lightning Observation Results in Japan
- (1)
- For the 500 kV transmission line, a large disparity exists between the total frequencies of lightning strikes calculated using classic model and the observed data.Regarding the 500 kV transmission line, the total frequency of lightning strikes obtained using the EGM proposed in [16] was close to that of observed data. However, a large difference can still be observed in the calculated frequency of lightning strikes of each phase, especially the upper and lower phases.The frequency of lightning strikes of each phase in 500 kV transmission line computed by the improved EGM proposed in the paper is in strong agreement with the observed data.
- (2)
- Regarding the 1000 kV transmission line, both the total frequency of lightning strikes and each phase calculated by the classic EGM are substantially different from those of the observed data, indicating that the classic EGM is not suitable for application in 1000 kV transmission lines.The total frequency of lightning strikes calculated by the EGM proposed in [16] was close to the observed data regarding the 1000 kV transmission lines. However, the substantial difference can still be observed between the calculated frequency of lightning strikes of each phase, especially the upper and lower phase.
3.3. Analysis of Calculation Results of UHV Transmssion Line in China
4. Conclusions
- In this study, using data from the rod-rod and rod-plane gap impulse voltage discharge test, where the gap distance were 1–10 m, voltage waveform was 20/2500 µs, with the probability distribution of lightning strike velocity observed by Idone, the relationship between the lightning current and striking distance was amended.
- According to the test results, when the gap distance was lower than 4 m, the 50% discharge voltage of the rod-plane gap was larger than that of the rod-rod gap. When the gap distance exceeded 4 m, the size relationship between two gaps discharge voltages reversed. Thus, the correction factor for the ground was revised to 1.25 based on data firstly.
- By comparing the results calculated using various EGMs and observed data in Japan, both the total frequency of lightning strikes and each phase calculated by the improved EGM proposed in this paper were close to those of the observed data.
- As observed in the calculated results of 1000 kV transmission line in China, the middle conductor tended to suffer more lightning strikes, but the whole shielding failure rate was minor, which is consistent with the actual operation states of 1000 kV transmission lines in China.
- The EGM proposed in the paper is suitable for application in EHV and UHV transmission lines and, therefore, could serve as a basis for lightning shielding designs for EHV and UHV transmission lines.
Acknowledgments
Author Contributions
Conflicts of Interest
References
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No. | Authors | Year | a | b | Kg |
---|---|---|---|---|---|
(1) | Wagner et al. [20] | 1961 | 14.2 | 0.42 | 1 |
(2) | Golde et al. [4] | 1963 | 3.3 | 0.78 | 1 |
(3) | Young et al. [5] | 1963 | 27 (hg < 18 m); 27 × 444/(462 − hg)(hg ≥ 18 m) | 0.32 | 1 (hg < 18 m); (462 − hg)/444 (hg ≥ 18 m) |
(4) | Armstrong and Whitehead. [3] | 1968 | 6.72 | 0.80 | 0.9 |
(5) | Brown and Whitehead et al. [6] | 1969 | 7.1 | 0.75 | 0.9 |
(6) | Love [7] | 1973 | 10 | 0.65 | 1 |
(7) | J.G. Andeson et al. [8] | 1982 | 8 | 0.65 | 0.64 (EHV) 0.8 (UHV) 1 (OTHER) |
(8) | IEEE Group [9] | 1985 | 8 | 0.65 | 0.64 (EHV) 0.8 (UHV) |
(9) | IEEE 1243-1997 [10] | 1997 | 10 | 0.65 | 0.36 + 0.17ln(43 − hc)(hc < 40 m) 0.55 (hc ≥ 40 m) |
(10) | Taniguchi [16] | 2010 | 1.42 | 1.1 |
Method | RMSE (500 kV) | RMSE (1000 kV) |
---|---|---|
Classic EGM | 0.2261 | 0.4470 |
EGM in [16] | 0.1635 | 0.3918 |
Improved EGM in this paper | 0.1538 | 0.3488 |
Phase | Frequency of Lightning Strikes Strokes/100 km/Year | Shielding Failure Rate Strokes/100 km/Year | |
---|---|---|---|
The improved EGM | Upper | 0.2725 | 2.737 × 10−4 |
Middle | 0.6806 | 2.694 × 10−4 | |
Lower | 0.4535 | 0 | |
Total | 1.4065 | 5.431 × 10−4 |
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Deng, Y.; Wang, Y.; Li, Z.; Dai, M.; Wen, X.; Lan, L.; An, Y.; E, S. Improved Electrogeometric Model Suitable for EHV and UHV Transmission Lines Developed through Breakdown Testing for Long Air Gaps. Energies 2017, 10, 333. https://doi.org/10.3390/en10030333
Deng Y, Wang Y, Li Z, Dai M, Wen X, Lan L, An Y, E S. Improved Electrogeometric Model Suitable for EHV and UHV Transmission Lines Developed through Breakdown Testing for Long Air Gaps. Energies. 2017; 10(3):333. https://doi.org/10.3390/en10030333
Chicago/Turabian StyleDeng, Yeqiang, Yu Wang, Zhijun Li, Min Dai, Xishan Wen, Lei Lan, Yunzhu An, and Shenglong E. 2017. "Improved Electrogeometric Model Suitable for EHV and UHV Transmission Lines Developed through Breakdown Testing for Long Air Gaps" Energies 10, no. 3: 333. https://doi.org/10.3390/en10030333