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Ju Tang
School of Electrical Engineering and Automation, Wuhan University, Wuhan 430072, China

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Journal article
Published: 06 January 2021 in Measurement
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Ring Main Units (RMU) are commonly used in the power system. At present, there is no example of partial discharge (PD) detection in RMU by optical method. In this article, the PD in RMU was detected by optical method. Meanwhile, the characteristics of the optical signals and the influential factors have been analyzed. The phase, amplitude and quantity characteristics of the PD optical signals in the positive and negative half cycle was analyzed and listed and we can find the PD optical signals under four typical insulating defects have their own characteristics; if the output of the PMT have not reach it saturation value, the maximum amplitude of the optical signals will increase with the increase of the applied voltage while the average amplitude of the optical signals did not always increase except the insulation gap defect; besides, the number of the optical signals also have a positive relationship with the applied voltage. When the optical receiving length quadruple, the initial PD voltage (IPDV) of optical method has decreased about 14.7% while the number of PD optical signals has increased about 1046.5%; when the pressure changing from 0.1 MPa to 0.14 MPa, the IPDV has increased about 83.65% while the signals number has decreased about 36.23%; when the distance between the optical fiber and the defect model changing from 2.5 cm to 7.5 cm, the IPDV has increased about 9.3% while the signals number has decreased about 65.7%.

ACS Style

Hongtu Cheng; Xiaoxing Zhang; Ju Tang; Song Xiao; Tingting Wang; Bing Luo; Shuangshuang Tian. The application of fluorescent optical fiber in partial discharge detection of Ring Main Unit. Measurement 2021, 174, 108979 .

AMA Style

Hongtu Cheng, Xiaoxing Zhang, Ju Tang, Song Xiao, Tingting Wang, Bing Luo, Shuangshuang Tian. The application of fluorescent optical fiber in partial discharge detection of Ring Main Unit. Measurement. 2021; 174 ():108979.

Chicago/Turabian Style

Hongtu Cheng; Xiaoxing Zhang; Ju Tang; Song Xiao; Tingting Wang; Bing Luo; Shuangshuang Tian. 2021. "The application of fluorescent optical fiber in partial discharge detection of Ring Main Unit." Measurement 174, no. : 108979.

Journal article
Published: 06 December 2019 in Energies
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C6F12O has been introduced as the potential alternative gas to SF6 because of its excellent insulation properties and great eco-friendly performance. Considering that C6F12O may react with the internal materials of switchgears in practical applications, its compatibility with metal materials must be tested to evaluate its long-term application possibilities. In this work, the compatibility of C6F12O–N2 gas mixtures with aluminum and copper was tested at different temperatures by setting up a heat-aging reaction platform between the gas and each metal. The metal surface morphology and gas composition before and after the reaction were compared and analyzed. The results show that the surface color of the copper sheet changed considerably, and the corrosion degree of the surface deepened with the increase of temperature. The decomposition of C6F12O was also promoted. In contrast, aluminum did not react severely with the gas mixture. The compatibility of the gas mixture with aluminum was generally better than that of copper.

ACS Style

Ran Zhuo; Qi Chen; Dibo Wang; Mingli Fu; Ju Tang; Juntai Hu; Yanlei Jiang. Compatibility between C6F12O–N2 Gas Mixture and Metal Used in Medium-Voltage Switchgears. Energies 2019, 12, 4639 .

AMA Style

Ran Zhuo, Qi Chen, Dibo Wang, Mingli Fu, Ju Tang, Juntai Hu, Yanlei Jiang. Compatibility between C6F12O–N2 Gas Mixture and Metal Used in Medium-Voltage Switchgears. Energies. 2019; 12 (24):4639.

Chicago/Turabian Style

Ran Zhuo; Qi Chen; Dibo Wang; Mingli Fu; Ju Tang; Juntai Hu; Yanlei Jiang. 2019. "Compatibility between C6F12O–N2 Gas Mixture and Metal Used in Medium-Voltage Switchgears." Energies 12, no. 24: 4639.

Journal article
Published: 29 September 2018 in Processes
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The c-C4F8 gas is considered to have great potential as a gaseous medium for gas-insulated equipment, due to its good insulation properties and its relatively low greenhouse gas potential (GWP) relative to SF6. However, the decomposition is an important indicator of its use in equipment. In this paper, the decomposition characteristics of c-C4F8 and the influence by oxygen have been explored through experiments and theoretical calculations. Firstly, the breakdown test of mixed gas was carried out and the precipitated elements of the electrodes and breakdown products of gas mixture were analyzed by X-ray photoelectron spectroscopy (XPS) and gas chromatography mass spectrometry (GC-MS). At the same time, the differences in decomposition products have also been studied when a small amount of O2 was present. The path and mechanism of c-C4F8 decomposition is then discussed, based on density functional theory (DFT). The results show that the black powdery substance descends on the electrode surface after the breakdown of the mixture of c-C4F8/N2 gas containing O2, and its main constituent elements are C, O and F. O2 can promote the decomposition of c-C4F8. The mixture with O2 produced a large number of additional toxic and corrosive COF2 in addition to generating more CF4, C2F4, C2F6, C3F6 and C3F8. The GWP values of the products are lower than SF6. Comprehensive insulation properties and decomposition characteristics, c-C4F8 should not be mixed with dry air for use, and the oxygen content should be strictly controlled in c-C4F8 mixed gas.

ACS Style

Song Xiao; Shuangshuang Tian; Xiaoxing Zhang; Yann Cressault; Ju Tang; Zaitao Deng; Yi Li. The Influence of O2 on Decomposition Characteristics of c-C4F8/N2 Environmental Friendly Insulating Gas. Processes 2018, 6, 174 .

AMA Style

Song Xiao, Shuangshuang Tian, Xiaoxing Zhang, Yann Cressault, Ju Tang, Zaitao Deng, Yi Li. The Influence of O2 on Decomposition Characteristics of c-C4F8/N2 Environmental Friendly Insulating Gas. Processes. 2018; 6 (10):174.

Chicago/Turabian Style

Song Xiao; Shuangshuang Tian; Xiaoxing Zhang; Yann Cressault; Ju Tang; Zaitao Deng; Yi Li. 2018. "The Influence of O2 on Decomposition Characteristics of c-C4F8/N2 Environmental Friendly Insulating Gas." Processes 6, no. 10: 174.

Journal article
Published: 01 October 2017 in Energies
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Scientific evaluation of partial discharge (PD) severity in gas-insulation switchgear (GIS) can assist in mastering the insulation condition of in-service GIS. Limited theoretical research on the laws of PD deterioration leads to a finite number of evaluation features extracted and subjective features selected for PD severity assessment. Therefore, this study proposes a minimum-redundancy maximum-relevance (mRMR) algorithm-based feature optimization selection method to realize the scientific and reasonable choice of PD severity features. PD ultra-high frequency data of varying severities are produced by simulating four typical insulation defects in GIS, which are then collected in the lab. A 16-dimension feature set describing PD original characteristics is abstracted in phase-resolved partial discharge (PRPD) mode, and the more informative evaluation feature set characterizing PD severity is further excavated by the mRMR method. Finally, a support vector machine (SVM) algorithm is employed as the classifier for intelligent evaluation to compare the evaluation effects of PD severity between the feature set selected by mRMR and the feature set is composed of discharge times, amplitude value, and time intervals obtained traditionally based on discharge change theory. The proposed comparison test showed the effectiveness of the mRMR method in informative feature selection and the accuracy of PD severity assessment for all defined defects.

ACS Style

Ju Tang; Miao Jin; Fuping Zeng; Siyuan Zhou; Xiaoxing Zhang; Yi Yang; Yan Ma. Feature Selection for Partial Discharge Severity Assessment in Gas-Insulated Switchgear Based on Minimum Redundancy and Maximum Relevance. Energies 2017, 10, 1516 .

AMA Style

Ju Tang, Miao Jin, Fuping Zeng, Siyuan Zhou, Xiaoxing Zhang, Yi Yang, Yan Ma. Feature Selection for Partial Discharge Severity Assessment in Gas-Insulated Switchgear Based on Minimum Redundancy and Maximum Relevance. Energies. 2017; 10 (10):1516.

Chicago/Turabian Style

Ju Tang; Miao Jin; Fuping Zeng; Siyuan Zhou; Xiaoxing Zhang; Yi Yang; Yan Ma. 2017. "Feature Selection for Partial Discharge Severity Assessment in Gas-Insulated Switchgear Based on Minimum Redundancy and Maximum Relevance." Energies 10, no. 10: 1516.

Article
Published: 09 August 2017 in Energies
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This paper explores the decomposition characteristics of a new type of environmentally friendly insulating gas C6F12O and N2 mixed gas under AC voltage. The breakdown behavior of 3% C6F12O and N2 mixed gas in quasi-uniform field was investigated through a breakdown experiment. The self-recovery of the mixed gas was analyzed by 100 breakdown experiments. The decomposition products of C6F12O and N2 under breakdown voltage were determined by gas chromatography–mass spectrometer (GC-MS). Finally, the decomposition process of the products was calculated by density functional theory, and the ionization energy, affinity, and molecular orbital gap of the decomposition products were also calculated. The properties of the decomposition products were analyzed from the aspects of insulation and environmental protection. The experimental results show that the 3% C6F12O and N2 mixed gas did not show a downward trend over 100 breakdown tests under a 0.10 MPa breakdown voltage. The decomposition products after breakdown were CF4, C2F6, C3F6, C3F8, C4F10, and C5F12. The ionization energies of several decomposition products are more than 10 eV. The Global Warming Potential (GWP) values of the main products are lower than SF6. C2F6, C3F8, and C4F10 have better insulation properties.

ACS Style

Xiaoxing Zhang; Shuangshuang Tian; Song Xiao; Zaitao Deng; Yi Li; Ju Tang. Insulation Strength and Decomposition Characteristics of a C6F12O and N2 Gas Mixture. Energies 2017, 10, 1170 .

AMA Style

Xiaoxing Zhang, Shuangshuang Tian, Song Xiao, Zaitao Deng, Yi Li, Ju Tang. Insulation Strength and Decomposition Characteristics of a C6F12O and N2 Gas Mixture. Energies. 2017; 10 (8):1170.

Chicago/Turabian Style

Xiaoxing Zhang; Shuangshuang Tian; Song Xiao; Zaitao Deng; Yi Li; Ju Tang. 2017. "Insulation Strength and Decomposition Characteristics of a C6F12O and N2 Gas Mixture." Energies 10, no. 8: 1170.

Journal article
Published: 01 August 2017 in Energies
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The decomposition characteristics of a SF6 gas-insulated medium were used to diagnose the partial discharge (PD) severity in DC gas-insulated equipment (DC-GIE). First, the PD characteristics of the whole process were studied from the initial PD to the breakdown initiated by a free metal particle defect. The average discharge magnitude in a second was used to characterize the PD severity and the PD was divided into three levels: mild PD, medium PD, and dangerous PD. Second, two kinds of voltage in each of the above PD levels were selected for the decomposition experiments of SF6. Results show that the negative DC-PD in these six experiments decomposes the SF6 gas and generates five stable decomposed components, namely, CF4, CO2, SO2F2, SOF2, and SO2. The concentrations and concentration ratios of the SF6 decomposed components can be associated with the PD severity. A minimum-redundancy-maximum-relevance (mRMR)-based feature selection algorithm was used to sort the concentrations and concentration ratios of the SF6 decomposed components. Back propagation neural network (BPNN) and support vector machine (SVM) algorithms were used to diagnose the PD severity. The use of C(CO2)/CT1, C(CF4)/C(SO2), C(CO2)/C(SOF2), and C(CF4)/C(CO2) shows good performance in diagnosing PD severity. This finding serves as a foundation in using the SF6 decomposed component analysis (DCA) method to diagnose the insulation faults in DC-GIE and assess its insulation status.

ACS Style

Ju Tang; Xu Yang; Dong Yang; Qiang Yao; Yulong Miao; Chaohai Zhang; Fuping Zeng. Using SF6 Decomposed Component Analysis for the Diagnosis of Partial Discharge Severity Initiated by Free Metal Particle Defect. Energies 2017, 10, 1119 .

AMA Style

Ju Tang, Xu Yang, Dong Yang, Qiang Yao, Yulong Miao, Chaohai Zhang, Fuping Zeng. Using SF6 Decomposed Component Analysis for the Diagnosis of Partial Discharge Severity Initiated by Free Metal Particle Defect. Energies. 2017; 10 (8):1119.

Chicago/Turabian Style

Ju Tang; Xu Yang; Dong Yang; Qiang Yao; Yulong Miao; Chaohai Zhang; Fuping Zeng. 2017. "Using SF6 Decomposed Component Analysis for the Diagnosis of Partial Discharge Severity Initiated by Free Metal Particle Defect." Energies 10, no. 8: 1119.

Journal article
Published: 25 July 2017 in Energies
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Aimed to clarify the correlation characteristics between the internal partial discharge (PD) in negative direct current (DC) gas insulated system (GIS) and gas pressure initiated by two typical defects (i.e., free-metal particles and metal protrusion), this study on PD decomposition of sulfur hexafluoride (SF6) was investigated under different pressures on the basis of constructing a SF6 decomposition experimental platform with DC PD. Free-metal particles and metal protrusion in a GIS were simulated using a spherical-bowl electrode and a needle-plate electrode, respectively. Trends and differences in the performance of SF6 decomposition components SOF2, SO2F2, CO2, and SO2 at different pressures were compared and analyzed by experiments under different defects. Based on gas microscopic ionization theory, the relationship between the decomposition component and gas pressure was deduced and verified. The concentrations of different decomposition components were found to vary with the change in gas pressure under different defects, whereas the characteristic ratios of decomposition components versus gas pressure showed a similar trend.

ACS Style

Dong Yang; Ju Tang; Xu Yang; Ke Li; Fuping Zeng; Qiang Yao; Yulong Miao; Lincong Chen. Correlation Characteristics Comparison of SF6 Decomposition versus Gas Pressure under Negative DC Partial Discharge Initiated by Two Typical Defects. Energies 2017, 10, 1085 .

AMA Style

Dong Yang, Ju Tang, Xu Yang, Ke Li, Fuping Zeng, Qiang Yao, Yulong Miao, Lincong Chen. Correlation Characteristics Comparison of SF6 Decomposition versus Gas Pressure under Negative DC Partial Discharge Initiated by Two Typical Defects. Energies. 2017; 10 (8):1085.

Chicago/Turabian Style

Dong Yang; Ju Tang; Xu Yang; Ke Li; Fuping Zeng; Qiang Yao; Yulong Miao; Lincong Chen. 2017. "Correlation Characteristics Comparison of SF6 Decomposition versus Gas Pressure under Negative DC Partial Discharge Initiated by Two Typical Defects." Energies 10, no. 8: 1085.

Journal article
Published: 18 April 2017 in Energies
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Four typical types of artificial defects are designed in conducting the decomposition experiments of SF6 gas to obtain and understand the decomposition characteristics of SF6 gas-insulated medium under different types of negative DC partial discharge (DC-PD), and use the obtained decomposition characteristics of SF6 in diagnosing the type and severity of insulation fault in DC SF6 gas-insulated equipment. Experimental results show that the negative DC partial discharges caused by the four defects decompose the SF6 gas and generate five stable decomposed components, namely, CF4, CO2, SO2F2, SOF2, and SO2. The concentration, effective formation rate, and concentration ratio of SF6 decomposed components can be associated with the PD types. Furthermore, back propagation neural network algorithm is used to recognize the PD types. The recognition results show that compared with the concentrations of SF6 decomposed components, their concentration ratios are more suitable as the characteristic quantities for PD recognition, and using those concentration ratios in recognizing the PD types can obtain a good effect.

ACS Style

Ju Tang; Xu Yang; Gaoxiang Ye; Qiang Yao; Yulong Miao; Fuping Zeng. Decomposition Characteristics of SF6 and Partial Discharge Recognition under Negative DC Conditions. Energies 2017, 10, 556 .

AMA Style

Ju Tang, Xu Yang, Gaoxiang Ye, Qiang Yao, Yulong Miao, Fuping Zeng. Decomposition Characteristics of SF6 and Partial Discharge Recognition under Negative DC Conditions. Energies. 2017; 10 (4):556.

Chicago/Turabian Style

Ju Tang; Xu Yang; Gaoxiang Ye; Qiang Yao; Yulong Miao; Fuping Zeng. 2017. "Decomposition Characteristics of SF6 and Partial Discharge Recognition under Negative DC Conditions." Energies 10, no. 4: 556.