1. State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing 400044 China;
2. Guang Dong Electric Power Research Institute Guangzhou 510080 China;
3. China Electric Power Research Institute Beijing 100192 China
The electrical properties and service life of power transformers are directly affected by the moisture and aging of oil-paper insulation. To investigate the influences of moisture and aging on frequency domain spectroscopy(FDS) for accurately evaluating the moisture content and aging state in transformers, some experimental pressboards with different moisture contents and aging states were firstly prepared, and then the complex capacitance spectroscopy(C*) was measured. After that, a new method which can assess the moisture content and aging state by using the imaginary part of complex capacitance(C″) was proposed. The frequency domain dielectric characteristics(FDDC) utilized as the evaluation of moisture content and aging state of pressboards were also extracted, and the quantitative relations between FDDC and moisture content & degree of polymerization(DP) were proposed. Finally, the temperature influence on C* was eliminated by introducing “frequency shift of FDS”. Results show that the FDDC proposed in this paper are very sensitive to moisture content and aging state. The master curve of C* obtained by “frequency shift of FDS” could eliminate the temperature influence on C*.
[1] 舒印彪, 张文亮. 特高压输电若干关键技术研究[J]. 中国电机工程学报, 2007, 27(31): 1-6. Shu Yinbiao, Zhang Wenliang. Research of key technologies for UHV transmission[J]. Proceedings of the CSEE, 2007, 27(31): 1-6.
[2] Wang M, Vandermaar A J, Srivastava K D. Review of condition assessment of power transformers in service [J]. IEEE Electrical Insulation Magazine, 2002, 18(6): 12-25.
[3] 王世强, 张冠军, 魏建林, 等. 纸板的老化状态对其PDC特性影响的实验研究[J]. 中国电机工程学报, 2011, 31(34): 177-183. Wang Shiqiang, Zhang Guanjun, Wei Jianlin, et al. Experimental study of the aged states effects on pressboard PDC characteristics[J]. Proceedings of the CSEE, 2011, 31(34): 177-183.
[4] 王世强, 魏建林, 杨双锁, 等. 油纸绝缘加速热老化的频域介电谱特性[J]. 中国电机工程学报, 2010, 30(34): 125-131. Wang Shiqiang, Wei Jianlin, Yang Shuangsuo, et al. Frequency domain dielectric spectroscopy character- ristics of oil-paper insulation under accelerated thermal aging[J]. Proceedings of the CSEE, 2010, 30(34): 125-131.
[5] 廖瑞金, 杨丽君, 郑含博, 等. 电力变压器油纸绝缘热老化研究综述[J]. 电工技术学报, 2012, 27(5): 1-12. Liao Ruijin, Yang Lijun, Zheng Hanbo, et al. Reviews on oil-paper insulation thermal aging in power trans- formers[J]. Transactions of China Electrotechnical Society, 2012, 27(5): 1-12.
[6] 王伟, 马志青, 李成榕, 等. 纤维素老化对油纸绝缘水分平衡的影响[J]. 中国电机工程学报, 2012, 32(31): 100-105. Wang Wei, Ma Zhiqing, Li Chengrong, et al. Impact of cellulose aging on moisture equilibrium of oil- pressboard insulation[J]. Proceedings of the CSEE, 2012, 32(31): 100-105.
[7] Du Y, Zahn M, Lesieutre B C, et al. Moisture equilibrium in transformer paper-oil systems[J]. IEEE Electrical Insulation Magazine, 1999, 15(1): 11-20.
[8] Ekanayake C, Gubanski S M, Graczkowski A, et al. Frequency response of oil impregnated pressboard and paper samples for estimating moisture in transformer insulation[J]. IEEE Transactions on Power Delivery, 2006, 21(3): 1309-1317.
[9] 杨丽君. 变压器油纸绝缘老化特征量与寿命评估方法研究[D]. 重庆: 重庆大学, 2009.
[10] McNutt W J. Insulation thermal life considerations for transformer loading guides[J]. IEEE Transactions on Power Delivery, 1992, 7(1): 392-401.
[11] 廖瑞金, 郝建, 杨丽君, 等. 变压器油纸绝缘频域介电特征量与绝缘老化状态的关系[J]. 电工技术学报, 2012, 27(5): 43-49+76. Liao Ruijin, Hao Jian, Yang Lijun, et al. Relationship between frequency domain characteristic quantity and aging status of transformer oil-paper insulation[J]. Transactions of China Electrotechnical Society, 2012, 27(5): 43-49+76.
[12] Saha T K, Yao Z T. Experience with return voltage measurements for assessing insulation conditions in service-aged transformers[J]. IEEE Transactions on Power Delivery, 2003, 18(1): 128-135.
[13] Kuang Y C, Chen G, Jarmm P. Recovery voltage measurement on oil-paper insulation with simple geometry and controlled environment[C]. Proceedings of the 2004 IEEE International Conference on Solid Dielectrics, 2004: 739-742.
[14] Saha T K, Purkait P. Understanding the impacts of moisture and thermal aging on transformer's insulation by dielectric response and molecular weight measure- ments[J]. IEEE Transactions on Dielectrics and Elec- trical Insulation, 2008, 15(2): 568-582.
[15] Saha T K, Purkait P. Investigation of polarization and depolarization current measurements for the assessment of oil-paper insulation of aged transformers[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 2004, 11(1): 144-154.
[16] Saha T K, Purkait P. Effects of temperature on time-domain dielectric diagnostics of transformers[J]. Australian Journal of Electrical and Electronics Engineering, 2004, 1(3): 157-162.
[17] Blennow J, Ekanayake C, Walczak K, et al. Field Experiments with measurement of dielectric response in frequency domain for power transformer diagnostics [J]. IEEE Transactions on Power Delivery, 2006, 21(2): 681-688.
[18] Gubanski S M, Boss P. Dielectric response methods for diagnostics of power transformers[J]. IEEE Electrical Insulation Magazine, 2003, 19(3): 12-18.
[19] 王世强, 魏建林, 张冠军, 等. 温度对油纸绝缘介电响应特性的影响[J]. 电工技术学报,2012, 27(5): 50-55. Wang Shiqiang, Wei Jianlin, Zhang Guanjun, et al. Effect of temperature on dielectric response character- ristics of oil impregnated pressboard[J]. Transactions of China Electro technical Society, 2012, 27(5): 50-55.
[20] 马志钦, 廖瑞金, 郝建, 等. 温度对油纸绝缘极化去极化电流的影响[J]. 电工技术学报,2014, 29(4): 290-297. Ma Zhiqin, Liao Ruijin, Hao Jian, et al. Influence of temperature on polarization and depolarization current of oil-paper insulation [J]. Transactions of China Elec- trotechnical Society, 2014, 29(4): 290-297.
[21] 廖瑞金, 刘捷丰, 吕彦东, 等. 变压器油纸绝缘含水量定量评估的频域介电特征参量研究[J]. 电工技术学报, 2015, 30(1): 204-211.
Liao Ruijin, Liu Jiefeng, Lv Yandong, et al. Frequency domain dielectric characteristic parameter for quantita- tive assessment of moisture content of oil-paper insula- tion in power transformers[J]. Transactions of China Electrotechnical Society, 2015, 30(1): 204-211.
[22] 杨丽君, 齐超亮, 郝建, 等. 变压器油纸绝缘水分含量的频域介电特征参量及评估方法研究[J]. 电工技术学报, 2013, 28(10): 59-66.
Yang Lijun, Qi Chaoliang, Hao Jian, et al. Frequency- domain dielectric characteristic parameter and moisture content assessment methods study on frequency-domain dielectric spectroscopy of oil-paper insulation for transformers[J]. Transactions of China Electrotechnical Society, 2013, 28(10): 59-66.
[23] 郝建. 变压器油纸绝缘热老化的时频域介电和空间电荷特性研究 [D]. 重庆: 重庆大学, 2012.