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Cheng Shi

Bio: Cheng Shi is an academic researcher from North China Electric Power University. The author has contributed to research in topics: Insulator (electricity) & Partial discharge. The author has an hindex of 5, co-authored 11 publications receiving 159 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, the heat transfer surface charge accumulation model of operating DC-GIL was developed, including the nonlinear relationship between volume current in gas and electric field, and the space charge was also considered in the model.
Abstract: With this expected future advance of HVDC, the use of gas insulated transmission lines (GIL) for dc application are getting increasingly interesting. For now, the problem of surface charge accumulation on gas-insulator interface is one of the critical factors for the development of DC-GIL. In many previous works, the model of surface charge accumulation on insulator was investigated. However, the quantitative relationship between temperature and surface charge accumulation on insulator was not exactly obtained since the lack of complicated heat transfer progress in the model. In this paper, the heat transfer surface charge accumulation model of operating DC-GIL was developed, including the nonlinear relationship between volume current in gas and electric field. Moreover, the space charge was also considered in the model. Based on the developed model, temperature distributions in DC-GIL insulator under different current are obtained. Afterwards, the temperature impact on space charge density in the insulator, the saturation time of surface charge accumulation, the surface charge on the insulator surface, and the electric field distribution on the insulator were investigated. It was proven that the tangential component of the electric field reaches to 5.3 kV/mm on lower interface and 5.0 kV/mm on upper interface for Ti=378 K. This value increase 17.8% on lower interface and 17.6% on upper interface along with the conductor temperature from 298 K to 378 K. The data can be referred in the insulation design of DC-GIL.

78 citations

Journal ArticleDOI
TL;DR: In this article, a distributed power transformer partial discharge detection system based on phase-shifted fiber Bragg gratings (PS-FBG) is proposed, which can be installed inside the power transformer, which takes the advantage of the optical fiber status as an insulator.
Abstract: To overcome the low sensitivity of power transformer partial discharge (PD) detection by a lead zirconate titanate (PZT) sensor, we propose a novel PD detection system based on phase-shifted fiber Bragg gratings (PS-FBG). Compared with the conventional method, the proposed sensor can be installed inside the power transformer, which takes the advantage of the optical fiber status as an insulator. Distributed PD detection is achieved using wavelength and time-division multiplexing. Frequency response experiments indicate that the sensitivity of the PS-FBG is 8.46 dB higher than that of the conventional ultrasonic sensor. Moreover, a PD detection experiment shows that the PD sensitivity of the PS-FBG immersed in oil is 17.5 times higher than that of the PZT sensor. Furthermore, the multiplexing and the feasibility of defect localization of the proposed distributed PD detection system are demonstrated.

73 citations

Journal ArticleDOI
26 Jan 2018-Sensors
TL;DR: A novel optical remote passive measuring system for OHTL monitoring that has many advantages, such as easy installation, no flashover risk, distribution monitoring, better bandwidth, improved accuracy and higher reliability, is proposed.
Abstract: Galloping of overhead transmission lines (OHTLs) may induce conductor breakage and tower collapse, and there is no effective method for long distance distribution on-line galloping monitoring. To overcome the drawbacks of the conventional galloping monitoring systems, such as sensitivity to electromagnetic interference, the need for onsite power, and short lifetimes, a novel optical remote passive measuring system is proposed in the paper. Firstly, to solve the hysteresis and eccentric load problem in tension sensing, and to extent the dynamic response range, an ‘S’ type elastic element structure with flanges was proposed. Then, a tension experiment was carried out to demonstrate the dynamic response characteristics. Moreover, the designed tension sensor was stretched continuously for 30 min to observe its long time stability. Last but not the least, the sensor was mounted on a 70 m conductor model, and the conductor was oscillated at different frequencies to investigate the dynamic performance of the sensor. The experimental results demonstrate the sensor is suitable for the OHTL galloping detection. Compared with the conventional sensors for OHTL monitoring, the system has many advantages, such as easy installation, no flashover risk, distribution monitoring, better bandwidth, improved accuracy and higher reliability.

36 citations

Journal ArticleDOI
TL;DR: In this paper, a nonintrusive distributed optical fiber sensing system based on the phase-sensitive optical time domain reflectometer (phi-OTDR) and the optical fiber Michelson interference is proposed.
Abstract: To overcome the high cost and low-spatial resolution of the electrical discharge localization systems for the gas insulated line (GIL), a non-intrusive distributed optical fiber sensing system based on the phase-sensitive optical time domain reflectometer (phi-OTDR) and the optical fiber Michelson interference is proposed. In the system, the Michelson interference provides a trigger signal since it has a better sensitivity and a higher frequency response, and the phi-OTDR localizes the ultrasonic vibration induced by a discharge. First, the principle of the proposed discharge localization system is introduced. Then, the bandwidth and multi-points distributed sensing performances of the system are investigated based on the ultrasonic signal induced by a piezoelectric transducer. Furthermore, the localization results of experiment using gas insulated switchgear spacer discharges indicate that the sensing distance of the sensing system can reach 1 km and the positioning accuracy of the discharge is smaller than 15 m. Thus, the system meets the requirement of the GIL discharge localization. Contrary to the traditional GIL discharge methods, the system has several advantages, such as non-intrusive, better spatial resolution, lower cost, and greatly simplified structure.

26 citations

Proceedings ArticleDOI
25 Jun 2017
TL;DR: In this article, an ultrasonic detection system based on fiber Bragg grating (FBG) is developed for partial discharge (PD) detection in power transformers, and PD detection experiments based on multi-point FBG string with different center wavelength were conducted.
Abstract: As a traditional approach of partial discharge (PD) in power transformers, ultrasonic detection with piezoelectric transducers (PZT) has drawbacks of low sensitivity and low detection efficiency. In order to overcome these disadvantages, an ultrasonic detection system based on fiber Bragg grating (FBG) is developed for PD in power transformers. Take the advantage of good insulation ability and immunity to electromagnetic interference, the optical sensor can be put into the transformers and detect the weak PD signal directly. In this paper, ultrasonic detection theory of FBG was analyzed, and PD detection experiments in transformer oil were carried out to test the performance of this FBG ultrasonic detection system. Furthermore, in order to demonstrate the coherence and distributed measuring ability, PD detection experiments based on multi-point FBG string with different center wavelength were conducted. Study results show the performance of FBG ultrasonic detection system is better than traditional PZT sensor, and satisfactory detection coherence of FBG with different center wavelength is proved. Moreover, distributed ultrasonic measuring of PD in power transformers can be realized by multi-point FBG string with application of wavelength-division and time-division multiplexing technology.

8 citations


Cited by
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Journal ArticleDOI
Chuanyang Li1, Lin Chuanjie1, Bo Zhang1, Qi Li1, Weidong Liu1, Jun Hu1, Jinliang He1 
TL;DR: In this paper, a review of surface charge accumulation and related surface flashover phenomenon on spacers in compressed gases is presented, with newly identified factors that may affect surface charge transport and measurements thereof.
Abstract: Surface charges have the effect of changing the electric field over spacers in compressed gases, which may affect the stable operation of gas insulated equipment and could possibly trigger a catastrophic surface flashover without warning. In this paper, we review the literature on surface charge accumulation and related surface flashover phenomenon on spacers in compressed gases. A summary of experimental research of surface charge accumulation is presented and, the surface charge accumulation mechanism is also summarized, with some newly identified factors in mind that may affect surface charge transport and measurements thereof. Subsequently, the correlation between surface charge accumulation and the surface flashover phenomenon is thoroughly discussed, and the effect of surface charges on surface breakdown under applied voltage pulses of various waveforms is analyzed. Finally, several important research topics in this area are proposed. In addition, some ideas on potential surface charge control methods are presented to aid the design of a better spacer free from surface charges in future studies.

115 citations

Journal ArticleDOI
04 Jul 2018-Sensors
TL;DR: This work reviews the present and emerging trends in CFBG sensors, focusing on all aspects of the sensing element and outlining the application case scenarios for which CF BG sensors have been demonstrated.
Abstract: Fiber Bragg Gratings (FBGs) are one of the most popular technology within fiber-optic sensors, and they allow the measurement of mechanical, thermal, and physical parameters. In recent years, a strong emphasis has been placed on the fabrication and application of chirped FBGs (CFBGs), which are characterized by a non-uniform modulation of the refractive index within the core of an optical fiber. A CFBG behaves as a cascade of FBGs, each one reflecting a narrow spectrum that depends on temperature and/or strain. The key characteristic of CFBGs is that their reflection spectrum depends on the strain/temperature observed in each section of the grating; thus, they enable a short-length distributed sensing, whereas it is possible to detect spatially resolved variations of temperature or strain with resolution on the order of a millimeter over the grating length. Based on this premise, CFBGs have found important applications in healthcare, mechanical engineering, and shock waves analysis, among others. This work reviews the present and emerging trends in CFBG sensors, focusing on all aspects of the sensing element and outlining the application case scenarios for which CFBG sensors have been demonstrated.

106 citations

Journal ArticleDOI
04 Aug 2019-Sensors
TL;DR: An event recognition method based on deep learning is proposed in this paper, which directly uses the temporal-spatial data matrix from Φ-OTDR as the input of a convolutional neural network (CNN).
Abstract: Phase-sensitive optical time domain reflectometer (Φ-OTDR) based distributed optical fiber sensing system has been widely used in many fields such as long range pipeline pre-warning, perimeter security and structure health monitoring. However, the lack of event recognition ability is always being the bottleneck of Φ-OTDR in field application. An event recognition method based on deep learning is proposed in this paper. This method directly uses the temporal-spatial data matrix from Φ-OTDR as the input of a convolutional neural network (CNN). Only a simple bandpass filtering and a gray scale transformation are needed as the pre-processing, which achieves real-time. Besides, an optimized network structure with small size, high training speed and high classification accuracy is built. Experiment results based on 5644 events samples show that this network can achieve 96.67% classification accuracy in recognition of 5 kinds of events and the retraining time is only 7 min for a new sensing setup.

85 citations

Journal ArticleDOI
01 Jun 2020
TL;DR: In this paper, the characteristics of steady and transient electric field distributions were first introduced, followed by the concept of functionally graded materials (FGMs), and the development histories of FGM applied in electrical engineering and related optimisation methods were described in detail.
Abstract: The electric field distributions along gas-solid interfaces determine the reliability, lifetimes and sizes of gaseous insulated switchgears/pipelines (GIS/GIL), which also affect the reliability of power systems. In this study, the characteristics of steady and transient electric field distributions were first introduced, followed by the concept of functionally graded materials (FGMs). The development histories of FGM applied in electrical engineering and the related optimisation methods were described in detail. The field regulation effect and fabrication technology of different FGM insulators were also compared. To overcome the limitations of traditional FGM insulators, the design of surface FGM (SFGM) was proposed, together with their preparation methods and electrical performance. Furthermore, the future development prospects of FGM and SFGM insulators for compact GIS/GIL were summarised.

80 citations

Journal ArticleDOI
TL;DR: In this article, a distributed power transformer partial discharge detection system based on phase-shifted fiber Bragg gratings (PS-FBG) is proposed, which can be installed inside the power transformer, which takes the advantage of the optical fiber status as an insulator.
Abstract: To overcome the low sensitivity of power transformer partial discharge (PD) detection by a lead zirconate titanate (PZT) sensor, we propose a novel PD detection system based on phase-shifted fiber Bragg gratings (PS-FBG). Compared with the conventional method, the proposed sensor can be installed inside the power transformer, which takes the advantage of the optical fiber status as an insulator. Distributed PD detection is achieved using wavelength and time-division multiplexing. Frequency response experiments indicate that the sensitivity of the PS-FBG is 8.46 dB higher than that of the conventional ultrasonic sensor. Moreover, a PD detection experiment shows that the PD sensitivity of the PS-FBG immersed in oil is 17.5 times higher than that of the PZT sensor. Furthermore, the multiplexing and the feasibility of defect localization of the proposed distributed PD detection system are demonstrated.

73 citations