© The Institution of Engineering and Technology
Temperature has obvious effects on the tested results of frequency domain dielectric spectrum (FDS) method. To estimate the moisture content of field oilimmersed bushing, the effects of temperature must be considered and eliminated. In this study, the frequencydomain dielectric spectrum of 72.5 kV bushing samples with different moisture contents was tested at different temperatures. The law that temperature affects the results of FDS tests was analysed and concluded. Afterwards, a method to transfer the tested results to the reference temperature (15°C) was proposed. Finally, an estimation method of moisture content for field oilimmersed bushing was proposed and testified. The following conclusions can be concluded: (i) the effects of temperature on the FDS results may be divided into two aspects, i.e. one is along the horizontal axis and the other is along the vertical axis and (ii) based on the proposed method, the temperature effects on the results of FDS tests can be eliminated, and the moisture content of field oilimmersed bushing can be estimated effectively and feasibly.
References


1)

1. Li, C.X., Xia, Q., Zhao, Z.Y., et al: ‘Impact analysis of the capacitive coupling sensor on bushing external insulation’, IET Gener. Transm. Distrib., 2016, 10, (14), pp. 3663–3670.

2)

2. Hashemnia, N., AbuSiada, A., Islam, S.: ‘Detection of power transformer bushing faults and oil degradation using frequency response analysis’, IEEE Trans. Dielectr. Electr. Insul., 2015, 22, (6), pp. 222–229.

3)

3. Zhang, S.: ‘Analysis of some measurement issues in bushing power factor tests in the field’, IEEE Trans. Power Deliv., 2006, 21, (3), pp. 1350–1356.

4)

4. Zhou, L.J., Wu, G.N., Liu, J.: ‘Modelling of transient moisture equilibrium in oil–paper insulation’, IEEE Trans. Dielectr. Electr. Insul., 2008, 15, (3), pp. 872–878.

5)

5. Cui, Y., Ma, H., Saha, T.K., et al: ‘Multiphysics modelling approach for investigation of moisture dynamics in power transformers’, IET Gener. Transm. Distrib., 2016, 10, (8), pp. 1993–2001.

6)

6. Smith, D.J., McMeekin, S.G., Stewart, B.G., et al: ‘A dielectric frequency response model to evaluate the moisture content within an oil impregnated paper condenser bushing’, IET Sci. Meas. Technol., 2013, 7, (4), pp. 223–231.

7)

7. Zaengl, W.S.: ‘Dielectric spectroscopy in time and frequency domain for HV power equipment, part i: theoretical considerations’, IEEE Electr. Insul. Mag., 2003, 19, (5), pp. 5–19.

8)

8. Zaengl, W.S.: ‘Applications of dielectric spectroscopy in time and frequency domain for HV power equipment’, IEEE Electr. Insul. Mag., 2003, 19, (6), pp. 9–22.

9)

9. Wolny, S., Adamowicz, A., Lepich, M.: ‘Influence of temperature and moisture level in paper–oil insulation on the parameters of the cole–cole model’, IEEE Trans. Power Deliv., 2014, 29, (1), pp. 246–250.

10)

10. Bagheri, M., Phung, B.T., Blachburn, T.: ‘Influence of temperature and moisture content on frequency response analysis of transformer winding’, IEEE Trans. Electr. Insul., 2014, 21, (3), pp. 1393–1404.

11)

11. Fofana, I., Hemmatjou, H., Meghnefi, F., et al: ‘On the frequency domain dielectric response of oil–paper insulation at low temperatures’, IEEE Trans. Electr. Insul., 2010, 17, (3), pp. 799–807.

12)

12. Wang, D.Y., Zhou, L.J., Wang, L.J., et al: ‘Frequency domain dielectric response of oil gap in timevarying temperature conditions’, IEEE Trans. Electr. Insul., 2017, 24, (2), pp. 964–973.

13)

13. Blennow, J., Ekanayake, C., Walczak, K., et al: ‘Field experiences with measurements of dielectric response in frequency domain for power transformer diagnostics’, IEEE Trans. Power Deliv., 2006, 21, (2), pp. 681–688.

14)

14. Liao, R.J., Liu, J.F., Yang, L.J., et al: ‘Quantitative analysis of insulation condition of oil–paper insulation based on frequency domain spectroscopy’, IEEE Trans. Electr. Insul., 2015, 22, (1), pp. 322–334.

15)

15. Liao, R.J., Liu, J.F., Yang, L.J., et al: ‘Understanding and analysis on frequency dielectric parameter for quantitative diagnosis of moisture content in paper–oil insulation system’, IET Electr. Power Appl., 2015, 9, (3), pp. 213–222.

16)

16. Wang, D.Y., Zhou, L.J., Li, H.Z., et al: ‘Moisture estimation for oilimmersed bushing based on FDS method: at a reference temperature’, IET Gener. Transm. Distrib., 2018, .

17)

17. Jonscher, A.K.: ‘Universal relaxation in law’ (Chelsea Dielectrics Press, London, UK, 1996).

18)

18. Gubanski, S.M., Boss, P., Csépes, G.V., et al: ‘CIGRÉ task force 15.01.09: dielectric response methods for diagnostics of power transformers’, IEEE Electr. Insul. Mag., 2003, 19, (3), pp. 12–18.

19)

19. Zhong, L.S., Li, S.T., Xu, C.X., et al: ‘Dielectric physics and phenomenon in engineering’ (Xi'AN Jiaotong University Press, 2nd edn.), pp. 106–107.

20)

20. Badicu, L.V., Gorgan, B., Dumitran, L.M., et al: ‘Assessment of transformer mineral oil condition based on dc and ac conductivity’, IEEE Trans. Dielectr. Electr. Insul., 2012, 19, (5), pp. 1544–1551.

21)

21. Żukowski, P., Kołtunowicz, T.N., Kierczyński, K., et al: ‘Permittivity of a composite of cellulose, mineral oil, and water nanoparticles: theoretical assumptions’, Cellulose, 2016, 23, (1), pp. 175–183.

22)

22. Gao, J., Yang, L.J., Wang, Y.Y., et al: ‘Effect of moisture and thermal degradation on the activation energy of oil–paper insulation in frequency domain spectroscopy measurement’, IET Gener. Transm. Distrib., 2016, 10, (9), pp. 2042–2049.

23)

23. Żukowski, P., Kołtunowicz, T.N., Kierczyński, K., et al: ‘An analysis of AC conductivity in moist oilimpregnated insulation pressboard’, IEEE Trans. Electr. Insul., 2015, 22, (4), pp. 2156–2164.

24)

24. Saha, T.K., Purkait, P.: ‘Investigations of temperature effects on the dielectric response measurements of transformer oil–paper insulation system’, IEEE Trans. Power Deliv., 2008, 23, (1), pp. 252–260.

25)

25. Setayeshmehr, A., Fofana, I., Eichler, C., et al: ‘Dielectric spectroscopic measurements on transformer oil–paper insulation under controlled laboratory conditions’, IEEE Trans. Electr. Insul., 2008, 15, (4), pp. 1100–1111.

26)

26. García, D.F., García, B., Burgos, J.C.: ‘A review of moisture diffusion coefficients in transformer solid insulation – part 1: coefficients for paper and pressboard’, IEEE Electr. Insul. Mag., 2013, 29, (1), pp. 46–54.
http://iet.metastore.ingenta.com/content/journals/10.1049/ietgtd.2018.0194
Related content
content/journals/10.1049/ietgtd.2018.0194
pub_keyword,iet_inspecKeyword,pub_concept
6
6