Fluorescence Fiber Based Identification of Partial Discharges in Liquid Nitrogen for High-Temperature Superconducting Power Apparatus
05 Feb 2020-Vol. 4, Iss: 2, pp 1-4
TL;DR: In this paper, the Corona inception voltage (CIV) in liquid nitrogen (LN2) insulation is studied under fundamental ac and harmonic ac voltages with different values of total harmonic distortion (THD).
Abstract: Partial discharge (PD) in liquid nitrogen (LN2) insulation is a key issue in cryogenic or high-temperature superconducting power apparatus. In this letter, we experimentally demonstrate PD identification in LN2 using a fluorescent optical fiber sensor and compare its sensitivity to the conventional ultrahigh frequency (UHF) technique. The Corona inception voltage (CIV) in LN2 is studied under fundamental ac and harmonic ac voltages with different values of total harmonic distortion (THD). It is observed that CIV reduces with the increase in harmonic voltage with higher THD. Phase resolved partial discharge pattern, peak-to-peak voltage, and the energy content due to corona discharges measured by both fluorescence-based and UHF techniques follows the same trend, indicating the viability of the new technique.
Citations
More filters
TL;DR: In this article, a review of the most important developments in this emerging area, together with a description of the key parameters describing PL-POF performance and efficiency is provided, along with an overview of the emerging area of photoluminescence in polymer optical fibers.
Abstract: Polymer optical fibers (POFs) have been utilized in several applications since the late 1950s. Adding photoluminescence (PL) to the fiber considerably widens the optical functionality of POFs and opens new application fields. In recent years, the availability of laboratory-scale production methods with industrialization potential has triggered a surge of new studies and developments in the promising area of PL-POFs. These applications, profiting from the addition of PL to fibers, are identified in this review as: light harvesting, sensing, color illumination, anti-counterfeiting, and random lasing. Progress in these fields is foreseen to generate a need for larger quantities of fibers, therefore large-scale manufacturing and processing methods are becoming more relevant. This review thus provides an overview of the most important developments in this emerging area, together with a description of the key parameters describing PL-POF performance and efficiency.
22 citations
TL;DR: In this article, an experimental investigation of the corona discharge activity of punga oil under the influence of a local magnetic field and different voltage profiles (AC and DC voltages) using fluorescent fiber sensor as well as UHF sensor technique was conducted.
Abstract: This paper reports the experimental investigation of the corona discharge activity of punga oil under the influence of a local magnetic field and different voltage profiles (AC and DC voltages) using fluorescent fiber sensor as well as UHF sensor technique. The corona inception voltage (CIV) of punga oil is higher under negative DC voltage followed by positive DC and AC voltage, with a marginal reduction in its CIV magnitude observed on the impact of external magnetic field. The dominant frequency of the UHF signal obtained under AC voltage shifted towards lower frequency (0.6 GHz) with the influence of magnetic flux density to about 85 mT. The rise time, pulse width and energy content of the fluorescent signal formed due to corona activity under AC voltage is found to vary under high magnetic fields confirming the inception results. The fluorescent signals formed due to corona discharge under both AC and DC voltages have its dominant frequency at 1 MHz with no shift observed in the presence of magnetic field. Also, there is no variation in the phase resolved partial discharge (PRPD) pattern observed due to corona discharge (with and without magnetic field) signal using both UHF sensor and the fluorescent sensor. The fluorescent fiber-based technique provides a better accuracy on detecting the corona discharges in punga oil at an early stage compared to conventional UHF sensor. The breakdown voltage of punga oil under different voltage profiles with and without the effect of magnetic field follows normal distribution. The dielectric dissipation factor and electrostatic charging tendency (ECT) of punga oil is observed to be higher than the limit set for insulating fluids towards power transformer operation.
18 citations
TL;DR: In this paper, the effect of corona discharges on the surface morphology characteristics of the nanocomposites was analyzed by measuring contact angle, surface profile measurement using atomic force microscopy (AFM), and characterized by multiresolution signal decomposition (MRSD) technique.
Abstract: Silicone rubber nanocomposites were prepared using 1, 3, 5, and 10 wt% of alumina nanofiller. Corona inception voltage (CIV) due to water droplets was measured using fluorescence technique, and it has decreased for alumina-added silicone rubber nanocomposites and with corona-aged samples. The effect of the corona discharges on the surface morphology characteristics of the nanocomposites was analyzed by measuring contact angle, surface profile measurement using atomic force microscopy (AFM), and characterized by adopting multiresolution signal decomposition (MRSD) technique. The addition of the alumina nanofiller suppressed the surface roughness for the corona-aged nanocomposites and 5-wt% sample observed to have the lowest surface roughness values. Recovery of the surface roughness caused by corona discharges was analyzed at different time intervals, and it was observed that alumina nanoparticle-added silicone rubber showed an incremental reduction in the roughness recovery rate. The laser-induced breakdown spectroscopy (LIBS) technique was adopted to analyze the nanocomposites after the corona aging, and further plasma temperature was evaluated at different recovery times. The addition of an alumina nanofiller increased the plasma temperature, and 5-wt% samples have the lowest plasma temperature recovery rate after corona aging. The analysis of the study indicates that the corona-aged silicone rubber specimen surface properties recover in 8 h of resting time period.
12 citations
TL;DR: In this paper , an experimental investigation of the impact of magnetic field on corona discharge activity in mineral oil, using both ultrahigh-frequency (UHF) and fluorescence techniques under ac voltage.
Abstract: This article reports an experimental investigation of the impact of magnetic field on corona discharge activity in mineral oil, using both ultrahigh-frequency (UHF) and fluorescence techniques under ac voltage. The results show that corona inception voltage (CIV) increased under ac voltage with varying harmonic frequencies without considering any phase shift and reduced marginally under magnetic field. In addition, the impact of the magnetic field shifted the dominating frequency of the UHF signal (0.9 GHz) obtained under ac voltage toward lower frequencies (0.3 and 0.6 GHz). Under high magnetic fields, the parameters such as rise time, fall time, and pulsewidth of the fluorescence signal increased in its magnitude compared to its effect without a magnetic field. Also, using both the UHF sensor and the fluorescence sensor, there was no clear difference in the phase-resolved partial discharge (PRPD) pattern caused by corona discharge (with and without magnetic field). Furthermore, the number of discharges is observed to be high under the impact of harmonic ac voltages with third- and seventh-order containing total harmonic distortions (THDs) of 4% and 40%.
11 citations
TL;DR: A novel method based on the UHF antenna and the truncated singular value decomposition (TSVD) regularization method that can accurately locate the PD source is developed and verified by theoretical verification and field tests.
Abstract: Ultra-high frequency (UHF) technology has been widely used in partial discharge (PD) source localization based on the time difference of arrival (TDOA). However, the TDOA errors will then lead to the ill-conditioned problem of matrix ${A}$ . A larger condition number will then lead to a more ill severe condition of linear equations $\textit {AX}={b}$ , and resulting in a decline in the localization accuracy. In this paper, a novel method for measuring the PD source has been developed based on the UHF antenna and the truncated singular value decomposition (TSVD) regularization method. First, the PD signals are obtained through the cooperation of five UHF antennas. Second, a spherical model linear transformation method is proposed for non-linear measurement equations. Then, to address the ill-conditioned problem of the measurement equations caused by the UHF antenna installation position, the linear measurement equations are improved with the pretreatment method. Finally, the TSVD regularization algorithm is applied to solve the UHF measurement equations with the ill-conditioned problems. The regularization parameter of the TSVD is then optimized by generalized cross-validation (GCV). In addition, the algorithm is verified by theoretical verification and field tests. The experimental results reveal that the proposed localization method can accurately locate the PD source.
7 citations
References
More filters
TL;DR: In this paper, the features of harmonic distortion which may affect the reliability of typical ac-power network equipment, such as lowvoltage self-healing capacitors used for reactive power and harmonic compensation, are investigated.
Abstract: This paper focuses on the features of harmonic distortion which may affect significantly the reliability of typical ac-power network equipment, such as low-voltage self-healing capacitors used for reactive power and harmonic compensation. Moreover, the effect of high-frequency pulse-like voltage generated by Adjustable Speed Drives (ASD) on electrical machine insulation is also investigated, resorting to life tests carried out on different insulating materials of the standard and "corona resistant" type, at electrical field levels able to incept partial discharges (PD).
123 citations
"Fluorescence Fiber Based Identifica..." refers background in this paper
...Studies have shown that harmonic voltages can reduce insulation strength and life significantly [15]....
[...]
TL;DR: A system for measuring the sensitivity of electric field sensors at UHF using a novel gigahertz transverse electromagnetic (GTEM) cell is described to enable calibration of UHF couplers that are used to detect insulation defects in gas insulated substations.
Abstract: A system for measuring the sensitivity of electric field sensors at UHF using a novel gigahertz transverse electromagnetic (GTEM) cell is described. The system was developed to enable calibration of UHF couplers that are used to detect insulation defects in gas insulated substations. The frequency response of a sensor is determined using fast Fourier transform (FFT) processing of its output voltage when it is subjected to a step electric field with a rise time of less than 300 ps. Provided the step response of the sensor is relatively short, the absorbing termination of the GTEM cell can be dispensed with, simplifying its construction. The need for impedance matching at the cell input can be eliminated by using a signal source that absorbs the reflected energy. In addition, the use of a wire septum offers the potential for improving field uniformity. A description of the measurement system is given, and some typical results are presented.
109 citations
TL;DR: In this article, an optoelectronic system for detecting partial discharges in a sheltered HV device is described, which consists of a fluorescent plastic optical fiber, with photomultipliers or photodiodes measuring the light intensity at the end of the fiber.
Abstract: An optoelectronic system for detecting partial discharges in a sheltered HV device is described. The system consists of a fluorescent plastic optical fiber, with photomultipliers or photodiodes measuring the light intensity at the end of the fiber. The result depends on various factors that might influence the optical detection sensitivity. Information is given on commercially available fluorescent fibers to facilitate the best choice of fiber/photodetector pair for a given application. >
62 citations
"Fluorescence Fiber Based Identifica..." refers background in this paper
...Studies showed a direct correlation between the PD current and the optical signal and have advantages like galvanic isolation and high sensitivity [5], [6]....
[...]
...Previous studies on optical detection of PD showed that the PD signal can be correlated with that of the PD current signal [5], [10], [11], whereas the correlation of an UHF signal with that of the current signal is not straight forward [4]....
[...]
TL;DR: A novel GIS PD detection sensor integrated with the optical fiber and UHF method is developed in this paper, which can fully utilize the advantages both of UHF and optical methods.
Abstract: Detecting partial discharge (PD) in gas-insulated switchgear (GIS) is an effective way to diagnose the insulation state of GIS When PD occurs in GIS, optical and electromagnetic signals will be emitted from the discharge source PD can be detected by analyzing these signals At present, the ultrahigh-frequency (UHF) method is one of the most popular methods for detecting the PD in GIS However, the optical method has not been in the field due to the problem of mounting optical sensor into GIS, even though it has higher sensitivity and better anti-interference performance To settle this problem, a novel GIS PD detection sensor integrated with the optical fiber and UHF method is developed in this paper, which can fully utilize the advantages both of UHF and optical methods The simulation results indicate that the integrated sensor can be mounted into GIS on the premise of not affecting the electric field distribution in GIS In addition, the integrated sensor has a good UHF performance The PD signals of typical defects at several locations were measured in a physical GIS using the integrated sensor The results show that the integrated sensor can detect the optical and UHF signals induced by PD at the same time The optical method has higher sensitivity than the UHF method for the protrusion defect The amplitude and the number of the optical signals induced by PD clearly decrease with the increase in the detection distance The studies in this paper are helpful to improve the accuracy and sensitivity of PD detection in GIS on site
57 citations
"Fluorescence Fiber Based Identifica..." refers background in this paper
...Previous studies on optical detection of PD showed that the PD signal can be correlated with that of the PD current signal [5], [10], [11], whereas the correlation of an UHF signal with that of the current signal is not straight forward [4]....
[...]
TL;DR: In this article, two streamers initiated in point-plane electrode geometry under impulse voltage are studied and two streamer types are identified: ''bush-like'' and ''filamentary'' streamers.
Abstract: Streamers initiated in point-plane electrode geometry under impulse voltage are studied. Characterization up to 30 kV in both polarities shows two streamer types. In negative polarity, only slow `bush-like' streamers with a velocity of about 100 m s-1 are observed. In positive polarity, both `bush-like' and filamentary streamers appear. Positive `bush-like' streamers have similar velocity as in negative polarity, whereas filamentary streamers have a propagation velocity up to 30 km s-1. This high velocity is correlated to large transient current and light emission. Spectroscopic study of the light emitted by filaments shows mainly the second positive system of nitrogen. This system allows us to estimate the gas temperature inside a filament by making a comparison with a numerically simulated spectrum. A temperature close to 500 K is found. Dilution of hydrogen gas in liquid nitrogen allows us to determine also the electron density by Stark broadening of the Balmer Hα line. An electron density of about 1.1018 cm-3 is found.
48 citations
"Fluorescence Fiber Based Identifica..." refers background or methods or result in this paper
...Based on the spectroscopic studies carried out during streamer propagation in LN2 [13], the discharge optical emission spectrum ranges from 250 to 500 nm, which indicates at the first stage that the present green fluorescent fiber can be used for PD detection....
[...]
...Similar observation has been made in a previous study where the UHF sensor is not effective in detecting PD generated due to the avalanche mechanism in GIS [13]....
[...]
...Similar characteristics are observed with the performance of a UHF sensor and a Fluorescence sensor in GIS [13]....
[...]