PD Location Research Articles

Field Plate Integration for Mitigating Partial Discharge Activity in PCB-Embedded Power Electronic Modules

This paper proposes a concept based on field plate (FP) integration inside printed circuit board (PCB)-embedded power modules. The goal is to reduce the electric field at their surface and thus increase the partial discharge inception voltage (PDIV). Electrostatic simulations are first carried out to analyze the electric field reduction induced by the use of FPs. Then, dedicated experiments are proposed to demonstrate that the actual PDIV increases in AC sinus 50 Hz when FPs are implemented. More specifically, it is observed that an optimal FP length exists. Several analyses based on simulations and experiments are thus proposed to explain this phenomenon. Finally, an assessment of PD activity and PD location is presented to support the analysis. AC sinus 50 Hz characterizations indicate that PDIV can be increased by 178% compared to PCBs without FPs with a proper definition of equipotential prolongation and PCB length.

Effects of dealumination on the methane-combustion activity of Pd/SSZ-13 catalysts

This study investigated the effects of dealumination on Pd/SSZ-13 catalysts for methane combustion. Pd(1)/SSZ-13 (HTA), prepared by treating the catalyst hydrothermally at 750 °C, displayed extremely low catalytic activity. In contrast, Pd(1)/SSZ-13 (DeAl), prepared by treating the SSZ-13 support hydrothermally followed by Pd impregnation, exhibited superior catalytic activity for methane oxidation. Catalytic properties, including zeolite hydrophobicity and Pd location and states, were investigated by using various characterization techniques to clarify the differences between the catalysts. Most Pd species in the Pd/SSZ-13 (HTA) catalyst existed as Pd ions, which were not very active for the reaction. On the contrary, most Pd species in the Pd(1)/SSZ-13 (DeAl) catalyst existed as PdO nanoparticles at the external surface, which were highly active for methane oxidation. The study results suggested that the amount of external PdO nanoparticles should be maximized in order to make Pd/SSZ-13 catalyst highly active for methane combustion, which was achieved by dealuminating the SSZ-13 support before Pd impregnation.

Simulation of PD Localization Through Digital Twin Model and Time-Reversal Algorithm Under the Semi-Enclosed Condition

Simulation of PD Localization Through Digital Twin Model and Time-Reversal Algorithm Under the Semi-Enclosed Condition

Selectivity Control in the Direct CO Esterification over Pd@UiO-66: The Pd Location Matters.

The selectivity control of Pd nanoparticles (NPs) in the direct CO esterification with methyl nitrite toward dimethyl oxalate (DMO) or dimethyl carbonate (DMC) remains a grand challenge. Herein, Pd NPs are incorporated into isoreticular metal-organic frameworks (MOFs), namely UiO-66-X (X=-H, -NO2 , -NH2 ), affording Pd@UiO-66-X, which unexpectedly exhibit high selectivity (up to 99 %) to DMC and regulated activity in the direct CO esterification. In sharp contrast, the Pd NPs supported on the MOF, yielding Pd/UiO-66, displays high selectivity (89 %) to DMO as always reported with Pd NPs. Both experimental and DFT calculation results prove that the Pd location relative to UiO-66 gives rise to discriminated microenvironment of different amounts of interface between Zr-oxo clusters and Pd NPs in Pd@UiO-66 and Pd/UiO-66, resulting in their distinctly different selectivity. This is an unprecedented finding on the production of DMC by Pd NPs, which was previously achieved by Pd(II) only, in the direct CO esterification.

Selectivity Control in the Direct CO Esterification over Pd@UiO‐66: The Pd Location Matters

AbstractThe selectivity control of Pd nanoparticles (NPs) in the direct CO esterification with methyl nitrite toward dimethyl oxalate (DMO) or dimethyl carbonate (DMC) remains a grand challenge. Herein, Pd NPs are incorporated into isoreticular metal–organic frameworks (MOFs), namely UiO‐66‐X (X=‐H, ‐NO2, ‐NH2), affording Pd@UiO‐66‐X, which unexpectedly exhibit high selectivity (up to 99 %) to DMC and regulated activity in the direct CO esterification. In sharp contrast, the Pd NPs supported on the MOF, yielding Pd/UiO‐66, displays high selectivity (89 %) to DMO as always reported with Pd NPs. Both experimental and DFT calculation results prove that the Pd location relative to UiO‐66 gives rise to discriminated microenvironment of different amounts of interface between Zr‐oxo clusters and Pd NPs in Pd@UiO‐66 and Pd/UiO‐66, resulting in their distinctly different selectivity. This is an unprecedented finding on the production of DMC by Pd NPs, which was previously achieved by Pd(II) only, in the direct CO esterification.

A high‐efficiency portable system for insulation condition assessment of wind farm inter‐array cables with double‐sided partial discharge detection and localisation

AbstractPartial discharge (PD) diagnosis is a crucial tool to assess the insulation condition of wind farm cables. Among PD diagnosis techniques, PD localisation is promising as it can provide target maintenance indicators on the insulation weak points of the cables. Accordingly, this paper developed a portable PD detection and location system for wind farm inter‐array cables. The system consists of two non‐invasive and lightweight testing units, which can be conveniently deployed on an energised cable, enabling highly efficient online PD diagnosis of the widely distributed inter‐array cables. The system achieves accurate PD localisation of the energised cable via an improved double‐sided travelling wave method. The method exhibits two superior features: the double‐sided testing units are accurately synchronised via the joint application of Global Position Systems and a pulse‐based interaction process, and a windowed phase difference method is proposed and integrated into the system to robustly estimate the time‐of‐arrival difference in low signal‐to‐noise ratio environment. Validation experiments were conducted on both a 10‐kV cable in the laboratory and a real 35‐kV cable in an on‐shore wind farm.

Acoustic Based Localization of Partial Discharge Inside Oil-Filled Transformers

This paper addresses the localization of Partial Discharge through a 3D Finite Element Method analysis of acoustic wave propagation inside a 3-phase 35kV transformer with the help of COMSOL Multiphysics software. Due to the complexity inside transformers, acoustic waves generated by PDs cannot simply be detected with typical acoustic sensors, especially when PDs happen inside inner windings. These waves are distorted and attenuated along with their propagation. The type, number, and position of sensors are essential factors in PD localization inside a transformer. A new installation arrangement of fiber-optic acoustic sensors inside the transformers is proposed with this information. This array of acoustic sensors has significant effects on PD localization accuracy and has immunity from on-site noise and interference; more importantly, they can be installed after transformer manufacturing. They are reachable if needed to be repaired or replaced. Several numerical studies have been carried out considering different PD source positions, and the Levenberge-Marquardt algorithm is employed for solving localization equations.

Hydrogen Activation and its Role in Co2 Hydrogenation on Isolated Pd Species of Cupd0.1/Γ-Al2o3: The Effect of Pd Location

Hydrogen Activation and its Role in Co2 Hydrogenation on Isolated Pd Species of Cupd0.1/Γ-Al2o3: The Effect of Pd Location

Research on PD monitoring and location method of automatic directional substation

The accurate positioning of partial discharge can effectively avoid the occurrence of insulation failure of power equipment, but most of the existing positioning devices are fixed antenna array, which is difficult to achieve multi angle discharge monitoring in space, and the positioning method is single and the positioning accuracy is not high. Therefore, this paper proposes an automatic directional monitoring device for partial discharge source, and proposes a precise positioning method based on fixed point iteration method. With this positioning method as the main method and the automatic directional device as the auxiliary method, the spatial multi angle positioning of partial discharge source is realized. Firstly, PD signal recognition algorithm is used to identify the fault of PD signal, and then the steering gear rotation angle is determined by the angle correlation calculation formula, so as to accurately identify the position and direction of PD source. On this basis, four antenna array positioning algorithm is used to accurately locate PD source. Finally, through the field simulation test, it is found that the angle error of automatic orientation is 3°. The position error of PD source is 0.19m, which verifies the feasibility of the proposed method and device.

Importance of Pd Distribution to Au–Pd Nanocrystals with High Refractive Index Sensitivity

Plasmonic metal nanoparticles (NPs) show promise in a variety of applications, ranging from theranostics to chemical sensing, with chemical sensing made possible by the sensitivity of the localized surface plasmon resonance (LSPR) to the surrounding dielectric environment. Au NPs have been the standard for LSPR sensing applications due to their narrow plasmon band, tunable LSPR maximum, and relative chemical stability; however, the comparatively low refractive index sensitivity (RIS) and morphological instability of Au nanostructures are limiting factors. Recent research has found that incorporating Pd into Au systems can increase RIS and impart multifunctionality, but how the distribution of Pd within Au-based nanostructures affects LSPR sensing is unclear. Here, Au–Pd heterostructures with different Au–Pd distributions were prepared to systematically study the effect of Pd distribution on RIS. Specifically, symmetrically branched Au nanocrystals with Oₕ symmetry (i.e., octopods) were selected as building blocks as their branch tips concentrate E-fields locally. Using these nanocrystals as seeds, Pd-tipped Au octopods and core@shell Au@Pd octopods were synthesized for comparison to alloy Au–Pd octopods and all-Au octopods. Through experiment and simulation, we show that RIS depends both on Pd loading and location in Au–Pd heterostructures, with the Pd-tipped Au octopods displaying the highest RIS while maintaining a moderate figure of merit. This systematic analysis highlights that localization of Pd at LSPR hotspots is critical to achieving the highest RIS, with this insight intended to guide design of future LSPR sensors that move beyond the all-Au standard.

A New Application of Rogowski Coil Sensor for Partial Discharge Localization in Power Transformers

This article deals with a new high efficient and cost effective lattice-Rogowski-coil sensor for partial discharge monitoring of power transformers. The sensor is a thin flat-shape printed circuit board type Rogowski-coil, which can be installed on the internal surface of the transformer tank with minimum disturbance to the normal operation of the transformer. Thanks to the accurate and desirable geometry of the sensor, precise monitoring can be carried out. Also, it was designed to handle the common trade-off between the low resonant frequency and high mutual inductance. An experimental setup for measuring the lumped model parameters of the sensor is made and it is shown that the desired resonance frequency of approximately 10 MHz is obtained. In order to evaluate the performance of the sensor, a specially prepared distribution transformer (20 kV/0.4 kV, 500 kVA) was considered. Partial discharge calibration pulses were injected into different locations of the winding of this transformer, and the ability of the sensor was verified in defect localization. Moreover, the effects of some practical aspects, like the value of the terminating resistor of the proposed special Rogowski-coil, its distance from transformer winding as well as the capability of the extracted features from detected PD signals, on the accuracy of PD localization are studied.

Applications of the Acoustic Method in Partial Discharge Measurement: A Review

This paper reviews the main features of acoustic emission technique. First, the characteristics of acoustic signals and their physics are addressed. Then, the structure of acoustic sensors employed for capturing signals is studied. In the next step, the acoustic method of PD measurement is compared with the standard electrical method. Afterward, the applications of AET in PD measurement in different equipment are summarized. All acoustic method and combined acoustic-electrical method for PD localization in transformers are discussed. Moreover, the applications of AET in the monitoring of GIS systems are explained, along with the acoustic behaviors of moving particles in these systems. Finally, the general considerations in the signal processing of the acoustic signals are reviewed.

A Comparison of Partial Discharge Sensors for Natural Gas Insulated High Voltage Equipment

The research in this paper consists of practical experimentation on a gas insulated section of high voltage equipment filled with carbon dioxide and technical air as a direct replacement to sulphur hexafluoride (SF6) and analyses the results of PD measurement by way of internal UHF sensors and external HFCTs. The results contribute to ongoing efforts to replace the global warming gas SF6 with an alternative such as pure carbon dioxide or technical air and are applicable to mixtures of electronegative gases that have a high content of buffer gas including carbon dioxide. The experiments undertaken involved filling a full-scale gas insulated line demonstrator with different pressures of CO2 or technical air and applying voltages up to 242 kV in both clean conditions and particle contaminated conditions. The results show that carbon dioxide and technical air can insulate a gas section normally insulated with SF6 at phase-to-earth voltage of 242 kV and that both HFCT and UHF sensors can be used to detect partial discharge with natural gases. The internal UHF sensors show the most accurate PD location results but external HFCTs offer a good compromise and very similar location accuracy.

Analysis of acoustic sensor placement for PD location in power transformer

Partial discharge PD is an abnormal activity that occurs in high-voltage components, such as power cables, switchgear, machines, and power transformers. Such activity needs to be diagnosed for the equipment to last longer as PD could harm the insulation and potentially lead to asset destruction from time to time. Moving one or more externally mounted acoustic sensors to different locations on the transformer tank is commonly used in order to detect and locate PD signal occurring in the power transformer. However, this procedure may lead to less accuracy in PD identification. Therefore, this research paper presents an analysis of acoustic sensor placement based on time of arrival TOA technique for PD location in a power transformer. The detection and location can be determined by permanently installing the acoustic sensor to provide valuable data in an early stage of occurrence for online condition PD monitoring. Several methods are available for the detection of PD signal, whereby one of the best choices is via acoustic emission AE . PD creates an ultrasonic signal used for PD detection. This paper proposes the possible placement of AE sensors to be mounted on the power transformer wall based on ideal and static PD signals. The sensors were placed in order to capture the PD signal without any disturbance signal from inside or outside the tank. The time for the signal for the first approach for each sensor is recorded to estimate the PD location using the TOA technique. A comparison between the least square method LSM and Gauss--Jordan elimination GJE for the TOA technique was analyzed to differentiate the resulting performance. This research utilized three different PD sources to apply the performance analysis on PD locations, while five cases were proposed to represent the five different placements of four sensors for the analysis. This research ultimately suggests that sensors be placed and randomly mounted on the four sides of the transformer tank, with one sensor allocated to one side. Among all five cases, Case 1 and Case 5 yielded a displacement error DE less than others, while between these two cases, Case 5 gave the lowest DE. The findings were recorded based on LSM and GJE methods used to differentiate the resulting performance.

Modelling of Acoustic Wave Propagation Due to Partial Discharge and Its Detection and Localization in an Oil-Filled Distribution Transformer

AbstractPartial discharge (PD) is the main cause of the insulation decay and hence periodical testing of the insulation condition of a distribution transformer is necessary. This paper presents a model of PD acoustic wave propagation, detection, and localization in an oil-filled distribution transformer using finite element method supported by COMSOL Multiphysics software. Using an acoustic module and AC/DC module of COMSOL Multiphysics software, oil filled distribution transformer, and the acoustic piezoelectric sensor are simulated to analyze and detect the PD inside the transformer. PD is numerically simulated in the transformer windings, core, and oil ducts that produce acoustic wave signal. The distribution of the acoustic pressure wave inside the model transformer is analyzed first. Next, the acoustic piezoelectric sensors are modelled at four different locations of the model transformer to detect the pressure acoustic wave signal induced due to PD in the transformer. Finally, using an artificial neural network (ANN), the localization, and identification of PD in various parts of the transformer have been analyzed. The results obtained for location and detection are quite encouraging.

S-Transform Aided Random Forest Based PD Location Detection Employing Signature of Optical Sensor

This paper presents a novel methodology to detect the location of single, double as well as multiple source partial discharge employing five optical sensors. An experimental setup has been developed in the laboratory to emulate the partial discharge occurring at various locations within insulation where optical sensors are mounted at particular positions to detect it. Analysis of experimental results shows that the signals captured by the sensors carry significant information relating to the location of partial discharge source. For identifying the location of partial discharge source, S-transform has been applied on captured signals and several features have been extracted. However, employing all the features extracted from the captured signals to detect the location makes the methodology complex and time consuming. Considering this fact, features are ranked according to their importance, which facilitates to select most effective feature extracted from signal captured by each of the sensors. Based on ranking, most important feature corresponding to each sensor has been chosen and used for identification of location through the random forest algorithm. In this case, the accuracy obtained for identifying the location is nearly 95.6%. However, the analysis results show that the accuracy level can further be improved by increasing the number of features.

Study on localization of transformer partial discharge source with planar arrangement UHF sensors based on singular value elimination

The large-scale power transformer gap leakage electromagnetic wave partial discharge detection method belongs to the external UHF detection method. This method can perform partial discharge insulation detection on the large-scale power transformer that is running without any modification of the power transformer, and the principle is simple and convenient to use. We have studied the reliability and the leakage electromagnetic wave propagation characteristics. However, this method requires UHF sensors in the same gap plane. When performing PD localization, it has the shortcomings of large positioning error and easy deviation of positioning results due to on-site noise pollution. For this problem, this paper proposes a PD source localization method based on singular value elimination. This method maps the three-dimensional coordinate sample set of the PD source to one-dimensional coordinates, and uses the improved box-plot diagram method to eliminate the singular values. Then the least square method is used to find the optimal coordinate of the real PD source. The proposed method has the advantages of greatly improving the data utilization efficiency of the PD sample set and effectively eliminating the singular values. Finally, the experimental verification of the proposed new method is carried out. The experimental results show that the proposed localization method can effectively improve the localization accuracy of PD source.

Design of UHF Antenna Sensor for Partial Discharge Detection in High Voltage S ubstation

Partial discharge early detection is a major issue in preventative maintenance. This condition is necessary to prevent greater damage in the high voltage system. The PD detection method using UHF sensors has become an attractive method because of its high sensitivity and the ability to detect the PD location. The objective of this study was to investigate the performance of an antipodal Vivaldi antenna (AVA) as the UHF sensor for the partial discharge detection. The simulation was carried out using CST Design StudioTM to analyze the optimal parameters of the antenna before it was manufactured. The result revealed that the AVA has the good capability to be used as UHF sensor for PD detection with the high sensitivity and good directivity.

Microtensile Bond Strength of Adhesive Systems in Different Dentin Regions on a Class II Cavity Configuration.

The aim of this study was to evaluate microtensile bond strength (µTBS) of self-etch and etch-and-rinse adhesives systems compared in different dentin regions (central-CD or proximal-PD) in a class II cavity configuration. A class II (mesial-oclusal-distal) cavity configuration was simulated on 20 extracted human third-molars (4 mm wide/3 mm deep). Etch-and-rinse adhesive (Scotchbond Multi Purpose, n=5, SBMP and Optibond FL, n=5, OPFL) and self-etch adhesives (Clearfil SE Bond, n=5, CSE and Optibond XTR, n=5, OPXTR) were applied. Class II restorations were performed by incremental technique and photo-activated (Bluephase/G2). Samples were sectioned to beam shape (1 mm² cross-section), placed on Geraldeli's device for µTBS test (0.5 mm/min cross-head speed). Fracture patterns were analyzed on stereomicroscope and classified as cohesive-resin, adhesive, mixed/resin or mixed/dentin. Samples (n=4) were prepared for scanning electron microscope observation. Data were submitted to one-way ANOVA with Split-Plot arrangement and Tukey's test (α=0.05). There were no statistically significant differences among SBMP, OPFL, CSE and OPXTR on CD (p>0.05). However, on PD for SBMP and OPFL, µTBS values were significantly lower compared to CSE and OPXTR (p<0.05). In all groups, mixed failure pattern was more frequently observed, except for SBMP/CD (adhesive). In class II type cavity configuration, PD location negatively influenced bond strength of etch-and-rinse adhesive systems. Opposite to self-etching adhesives, which presented higher bond strength values compared to etch-and-rinse adhesives in PD.

Multi-end PD location algorithm using segmented correlation and trimmed mean data filtering techniques for MV Underground Cable

Medium voltage underground cables are widely used in urban area as distribution power lines due to their advantages over overhead cables. Underground cables may suffer from partial discharge because of insulation degradation after certain period of time. In this paper, an improved multi-end partial discharge location algorithm called segmented correlation trimmed mean algorithm is proposed. The algorithm uses segmented correlation technique and trimmed mean data filtering technique to enhance the accuracy of partial discharge location algorithm. The algorithm had been tested in MATLAB environment which consists white Gaussian noise. First, discrete wavelet transform is carried out to suppress noisy signals. Next, segmented correlation technique is applied to the de-noised segmented partial discharge signals. Segmented correlation technique has manipulates partial discharge signals by performing cross correlation process on segmented partial discharge signals in order to reduce memory usage and algorithm execution time. Lastly, trimmed mean data filtering technique is applied to the estimated partial discharge location values to estimate new partial discharge location value. Trimmed mean data filtering technique does statistical process control on estimated partial discharge location values in order to minimize the error of estimated partial discharge location. The segmented correlation trimmed mean algorithm had been compared with the existing multi-end correlation-based algorithm. The result shown that the segmented correlation trimmed mean algorithm has better accuracy than multi-end correlation-based algorithm.