Nianwen Xiang

Nianwen Xiang

Hefei University of Technology

H-index: 11

Asia-China

About Nianwen Xiang

Nianwen Xiang, With an exceptional h-index of 11 and a recent h-index of 9 (since 2020), a distinguished researcher at Hefei University of Technology, specializes in the field of lightning protection, EMC, Electromagnetics.

His recent articles reflect a diverse array of research interests and contributions to the field:

An Analytical Carrier Recombination Turn-off Transient Model for High-Voltage IGBTs

Temperature evolution characteristics of stem root during dark period in positive long spark discharge

An Analytical Temperature-Dependent Turn-off Model for High-Voltage Field-Stop IGBTs Considering the Influence of Drive Circuit

Short Circuit Fault Characteristics of Low Frequency AC Transmission System Based on Modular Multilevel Matrix Converter

Nonlinear evolution of space synthetic electric field in positive DC corona mode transition

Research on Lightning Intrusion Wave Characteristics in Converter Station of Flexible Low Frequency Transmission System

Numerical simulation and experimental verification of plasma jet development in gas gap switch

Study on the discharge and defect characteristics of the binding wire to the insulated conductor in the distribution network

Nianwen Xiang Information

University

Hefei University of Technology

Position

___

Citations(all)

411

Citations(since 2020)

294

Cited By

202

hIndex(all)

11

hIndex(since 2020)

9

i10Index(all)

13

i10Index(since 2020)

8

Email

University Profile Page

Hefei University of Technology

Nianwen Xiang Skills & Research Interests

lightning protection

EMC

Electromagnetics

Top articles of Nianwen Xiang

An Analytical Carrier Recombination Turn-off Transient Model for High-Voltage IGBTs

Authors

Zhiyuan Zhang,Hengxin He,Kejie Li,Nianwen Xiang,Weijiang Chen

Journal

IEEE Transactions on Power Electronics

Published Date

2024/3/13

High-voltage insulated-gate bipolar transistors (IGBTs) have been extensively used in power electronic systems, such as railway traction inverters, flexible dc transmission systems, and wind turbines, and it is necessary to investigate transient modeling of high-voltage IGBTs. Based on the mechanism of the switching transient, this article proposes a new analytical model for the turn- off process of high-voltage IGBTs. First, considering the large base width of high-voltage IGBTs, the defect of the first-order approximation assumptions used in the existing model is analyzed in detail. Then, by using hyperbolic approximation, an improved solution method is developed for the transient ambipolar diffusion equation that considers the influence of carrier recombination in the base region. Finally, the accuracy of the proposed method is verified by comparing its simulation results with the experiment data obtained under the …

Temperature evolution characteristics of stem root during dark period in positive long spark discharge

Authors

Chen Cheng,Hengxin He,Yubin Huang,Zhong Fu,Aihua Zhao,Nianwen Xiang,Weijiang Chen

Journal

Journal of Applied Physics

Published Date

2024/2/7

Gas temperature plays an important role in the characterization of plasma parameters. The temperature evolution of stem roots during the dark period is at the heart of our understanding of the physical mechanism of streamer to the leader transition process in a long spark discharge. The quantitative schlieren system with high spatiotemporal resolution was designed to conduct positive leader discharge experiments with a 1.0 m rod-plate gap at atmospheric pressure, and the amplitude and rise time of positive impulse voltage waveforms were 380 kV and 200 μs, respectively. The time-resolved quantitative schlieren images of the discharge channel near the electrode tip can be captured to gather the temperature data of stem roots for case study. Further statistical tests revealed that due to the dispersion of the first streamer discharge, there were three evolutionary trends of gas temperature at the axis of the stem root …

An Analytical Temperature-Dependent Turn-off Model for High-Voltage Field-Stop IGBTs Considering the Influence of Drive Circuit

Authors

Zhiyuan Zhang,Hengxin He,Kejie Li,Nianwen Xiang,Weijiang Chen

Journal

IEEE Transactions on Power Electronics

Published Date

2024/4/22

With the improvement in device manufacturing technology, the insulated gate bipolar transistor (IGBT) has been widely used in power electronic systems (PESs), such as power transmission, railway traction inverters, and aerospace. There is an urgent need for the accurate transient electrical model of IGBTs. Based on the improved understanding of the carrier transport process in the high-voltage IGBT during the turn-off stage, this article proposes a new analytical temperaturedependent model of the turn-off transient process for field-stop IGBTs that considers the drive circuit's influence. Compared with existing analytical models, the proposed model improves the accuracy of the description of transient electrical behavior by considering the influence of carrier recombination. Finally, the accuracy of the proposed model is verified by comparing the simulation results with the experimental data obtained by the double …

Short Circuit Fault Characteristics of Low Frequency AC Transmission System Based on Modular Multilevel Matrix Converter

Authors

Zexin Zhao,Bin Han,Guoliang Zhao,Yunfei Xu,Zhengang Lu,Nianwen Xiang,Shulai Wang

Published Date

2023/2/24

Compared with power frequency AC transmission and DC transmission, low frequency AC transmission has its unique advantages, which is suitable for long distance transmission, large scale renewable generation and regulation of regional power grid. The fault characteristics affect the system design and operation, which is necessary to study. From the perspective of system topology and converter control, the characteristics of three-phase short circuit fault are analyzed and a simulation model is built on PSCAD for verification in this paper. After a fault occurs, it can be divided into two stages before and after the control responses. Before the control responses, the overvoltage is generated between the terminals of branch reactors and modular capacitors discharges. After the control responses, system characteristics are related to fault location and control strategy. The control and modulation of the converter can …

Nonlinear evolution of space synthetic electric field in positive DC corona mode transition

Authors

Jiayi Nie,Xing Fan,Nianwen Xiang,Kejie Li,Shengxin Huang,Weijiang Chen

Journal

Journal of Physics D: Applied Physics

Published Date

2023/9/8

Positive corona discharge in the air exists under several distinctive forms depending on DC voltage amplitude, including pulses or pulseless glow. Previous studies obtained the current and optical image characteristics of corona discharge through experiments. However, the synthesized electric field characteristics of the different corona modes have not been deeply studied by experiments, and lack of sufficient understanding of the effect of space charges. In this paper, electro-optical modulation technology is used to investigate the characteristics of the space synthetic electric field (SSE) for positive DC corona modes transition. The experimental results show the significant nonlinear evolution characteristics of the SSE and discharge modes transition with the increase of applied voltage. In the pulsed mode, the SSE first changes slowly and then increases sharply. As the applied voltage increases, the discharge …

Research on Lightning Intrusion Wave Characteristics in Converter Station of Flexible Low Frequency Transmission System

Authors

Shulai Wang,Nianwen Xiang,Jiawei Ni,Yifan Ke,Yeshou Hong,Jiahua Lei

Published Date

2023/5/12

Lightning strikes low-frequency transmission line towers or lightning protection lines, in addition to causing flashover of transmission line insulators, part of the lightning energy will invade the interior of the converter station along the wires in the form of overvoltage waves, causing damage to the insulation of key equipment in the station. In this paper, using the electromagnetic transient simulation program for a low- frequency project in Hangzhou, the electromagnetic transient model including the converter station and the incoming section of the transmission line is established, and the simulation research on the transient process of lightning intrusion wave is carried out. The lightning overvoltage at the key equipment, the simulation results show that the lightning overvoltage amplitude at the key equipment is up to 536.29kV when the intrusion wave is shielded under the existing arrester configuration, which will not …

Numerical simulation and experimental verification of plasma jet development in gas gap switch

Authors

Mudaser Ullah,Riffat Asim Pasha,Ghulam Yasin Chohan,Faisal Qayyum

Journal

Arabian Journal for Science and Engineering

Published Date

2015/3

Compact tension (CT) specimen is used to investigate the behavior of fatigue crack growth rate (FCGR) of preheat-treated tungsten inert gas (TIG) welded aluminum alloy (AA2219-T87) on MTS-810. Filler metal used for weld is AA2319. ASTM E399 standard provides a method to convert crack mouth opening displacement (CMOD) data to crack length in CT specimens. Calibration tests are performed to obtain the plots of CMOD versus load and CMOD versus crack ratio (a/W) for different crack lengths in the base metal and the welded metal. Cracks lengths are obtained optically and calculated from CMOD as per ASTM E399. Numerical simulation is used to relate the crack length with CMOD in base metal. Validity of the ASTM standard is verified with the results obtained. Paris curves are plotted and compared for both base metal and welded metal to study the effects of welding on FCGR. It is shown that …

Study on the discharge and defect characteristics of the binding wire to the insulated conductor in the distribution network

Authors

Nianwen Xiang,Yufeng Pan,Chaoqun Wang

Published Date

2023/5/12

The root cause of partial discharge at the overhead binding line of the distribution line is that the electric field strength increases and exceeds the initial electric field strength of the discharge, so it is important to analyze the factors affecting the change of the electric field strength. In this paper, the electric field distribution characteristics of the distribution line at the overhead binding line under normal working conditions are simulated and calculated, and the key characteristic quantities of the discharge and the possible positions of the discharge are obtained under three working conditions of the insulator under different deterioration degree, wetting degree and binding line structure. The simulation results show that the maximum electric field strength decreases from 6.72kV/cm when the conductor is intact to 4.63kV/cm with the deepening of insulator deterioration cracks; With the increase of the distance between the …

DC Bias Content Extraction of Power Transformer Under AC and DC Environment and its Suppression Measures

Authors

Zhiwei Chen,Yu Chen,Fei Xia,Tingli Cheng,Shengxin Huang,Nianwen Xiang

Journal

IEEE Transactions on Industrial Electronics

Published Date

2023/8/22

The phenomenon of transformer dc bias (TDB) will saturate the transformer core, resulting in the local overheating, accelerating the ageing of insulating material, and even affecting the transformer safe operation. Therefore, it is of great significance to carry out the TDB detection and suppression. In this article, first, according to the distortion characteristics of the transformer excitation current under TDB. This article presents a method for measuring the bias voltage content of the transformer in the ac/dc environment to detect TDB. Second, the value of TDB is calculated by measuring the voltage difference before and after the dc bias, so as to obtain the degree of TDB. The feasibility of this scheme is verified by multigroup simulations of single-phase transformer (SPT) and three-phase transformer (TPT). Finally, the SPT and TPT simulated experiments of TDB are designed, and one kind of TDB suppression is carried …

A full-wave PEEC model for thin-wire structure in the air and homogeneous lossy ground

Authors

Weiping Ye,Weidong Liu,Nianwen Xiang,Kejie Li,Weijiang Chen

Journal

IEEE Transactions on Electromagnetic Compatibility

Published Date

2023/2/17

This article presents an efficient full-wave partial element equivalent circuit (PEEC) formulation of thin-wire structure in the full space of air-homogeneous lossy ground for lightning transient analysis. First, the Green's functions for the case of an air-uniform ground are derived, which involve Sommerfeld-type integrals. Next, using the singularity subtraction technique, a new form of Green's functions is obtained, which has the advantage of being less singular and smooth compared with the original form. In the full-wave method, the efficient and accurate computation of partial elements is crucial for the practical application of the PEEC formulation. A three-dimensional cubic interpolation scheme is employed to accelerate the computation of Sommerfeld integrals. To improve the computational efficiency and accuracy of the interpolation, the continuity and symmetry of the Green's functions are investigated in a …

Simplified Calculation Method of Fault Current in Low Frequency Transmission System Based on M3C

Authors

Nianwen Xiang,Shouhong Ye

Published Date

2023/5/12

The low frequency transmission system based on modular multilevel matrix converter has the technical advantages of AC and DC transmission, and has unique advantages in the application of medium and long distance offshore wind power. The calculation of fault current is of great significance to relay protection setting calculation, electrical equipment selection and verification. Therefore, a simplified calculation method of fault current is proposed in this paper. Firstly, the transient process of fault is analyzed comprehensively. According to the energy conservation principle, the capacitance determined by the control strategy is equivalent in time domain, and then the analytical formulas of arm current and sub-module capacitance voltage before and after converter blocking are derived. The research shows that the equivalent method of time-varying capacitance before converter blocking is feasible. The peak value …

Experimental study on the axial growth characteristics of streamer stem during dark period in long spark discharge

Authors

Chen Cheng,Hengxin He,Yubin Huang,Zhong Fu,Aihua Zhao,Nianwen Xiang,Weijiang Chen

Journal

Physics of Plasmas

Published Date

2023/8/1

This paper presents an original investigation into the axial evolution of streamer stem during a dark period in long spark discharge. To obtain thermodynamic morphology and temperature distribution of stems, we set up a quantitative schlieren system with the temporal and spatial resolutions of 0.37 ls and 31lm/pixel, respectively. The quantitative schlieren observation experiments of positive leader discharge with a 1.0 m rod-plate gap were carried out, and the time-resolved quantitative schlieren images were captured. Furthermore, the temperature distribution of stems and its morphology evolution in the axial direction during a dark period were obtained. Due to the dispersion of first streamer discharge, the gas temperature in stem roots shows two evolutionary trends, namely, rising and falling. It was found that the gas temperature in stem decreased along the axis with the increase in the distance from stem root …

Fully decoupled branch energy balancing control method for modular multilevel matrix converter based on sequence circulating components

Authors

Zexin Zhao,Weijiang Chen,Zhichang Yang,Guoliang Zhao,Bin Han,Yunfei Xu,Nianwen Xiang,Shulai Wang

Journal

CSEE Journal of Power and Energy Systems

Published Date

2023/12/28

The modular multilevel matrix converter (M3C) is a potential frequency converter for low-frequency AC transmission. However, capacitor voltage control of high-voltage and large-capacity M3C is more difficult, especially for voltage balancing between branches. To solve this problem, this paper defines sequence circulating components and theoretically analyzes the influence mechanism of different sequence circulating components on branch capacitor voltage. A fully decoupled branch energy balancing control method based on four groups of sequence circulating components is proposed. This method can control capacitor voltages of nine branches in horizontal, vertical and diagonal directions. Considering influences of both circulating current and voltage, a cross decoupled control is designed to improve control precision. Simulation results are taken from a low-frequency transmission system based on PSCAD …

An interpretable convolutional neural network for VLF/LF lightning electric field waveform classification

Authors

Mahnoosh Tajmirriahi,Zahra Amini,Hossein Rabbani,Rahele Kafieh

Journal

IEEE Sensors Journal

Published Date

2022/3/14

In this study, a new deep learning-based methodology is developed for P300 detection in brain computer interface (BCI) systems based on time-frequency (TF) features of EEG signals coupled to deep learning. The TF distributions can transform EEG signals to the TF images by simultaneous representation of time and frequency properties of the signal. However, they do not display the energy distribution of signals at different scales identically and their advantages may be greatly incorporated by using them together. Here, four TF images of single-trail EEG signal are computed and the concatenation of the TF (cTF) images of each signal is developed to be used as training data for a simple and lightweight deep learning-based classifier. The applied TF distributions are spectrogram, Wigner–Ville distribution, Morlet-scalogram, and Bertrand distribution. Performance of method is evaluated over limited data acquired …

Study on the adaptability of traction power supply system under the operation of high density heavy haul train

Authors

Nianwen Xiang,Qiankun Yuan,Chaoqun Wang

Published Date

2023/5/12

While the operation of high-density heavy-load trains brings greater economic benefits, the increase in the number of trains running in the same power supply arm will lead to an increase in the burden and stability of the traction power supply system. Therefore, it is necessary to build a simulation model of the fully parallel AT traction power supply system and study the impact of high-density heavy haul train operation on the traction power supply system. Based on the PSCAD electromagnetic transient simulation software, this paper establishes the simulation model of traction power supply system, calculates the equivalent impedance model of heavy-load train through the relevant theory of electromagnetic field and the chain network model, and quantitatively analyzes the characteristics of the impact of heavy-load train on the traction network and traction substation under different operating conditions. The research …

Toward an Interpretable CNN Model for the Classification of Lightning‐Produced VLF/LF Signals

Authors

Lilang Xiao,Weijiang Chen,Yu Wang,Kai Bian,Zhong Fu,Nianwen Xiang,Hengxin He,Yang Cheng

Journal

Journal of Geophysical Research: Atmospheres

Published Date

2023/11/27

An interpretable convolutional neural network model is proposed for the classification of very low frequency and low frequency lightning electric field waveforms. This model adopts multi‐scale convolutional kernels and shortcut connections to enhance the ability of lightning waveform classification. Based on the data recorded from five provinces in China, the proposed model achieves an accuracy of 98.56% for a four‐type classification task including return strokes, the intra‐cloud lightning, preliminary breakdown, and narrow bipolar events. The proposed model is validated with another open‐source data set from Argentina with an accuracy of 98.45%, which shows good robustness. To ensure the classification, the features learned by the model are visualized. The class activation mapping (CAM) method is adopted to visualize the class‐specific contribution of different waveform parts by using the feature maps of …

Analytical Evaluation of Partial Elements in the Full-Wave PEEC Formulation for Thin-Wire Structure

Authors

Weiping Ye,Weidong Liu,Nianwen Xiang,Kejie Li,Weijiang Chen

Journal

IEEE Transactions on Electromagnetic Compatibility

Published Date

2023/7/26

This article presents new full-wave analytical formulas for the partial element involving the free-space Green's function in the modeling of thin-wire structures for lightning transient analysis. In the framework of the partial element equivalent circuit (PEEC) formulation for thin conductors, the partial elements are computed by double-folded line integrals. In layered media, the interaction integrals involve the dyadic Green's function, which contains the free-space Green's function term. The direct numerical computation of these integrals is time-consuming, which hinders the practical application of the full-wave method. Therefore, quasi-static (QS) analytical formulas for orthogonal meshes are widely used, which significantly reduces the computational overhead. However, these existing analytical formulas are derived under the QS hypothesis, which is not suitable for full-wave wideband analysis. The accurate analytical …

Study on the Grounding of Signal Equipment under the Overvoltage Action of Topographic Factors

Authors

Nianwen Xiang,Jiahua Lei,Chaoqun Wang,Wei Zhang

Published Date

2023/5/12

The transient calculation model of the electrified railway grounding system is established in the circuit solver. Considering the refraction and reflection process of the overvoltage traveling wave in the grounding system, it is analyzed that the amplitude and attenuation of overvoltage at four positions under different terrain inclination: the signal equipment is located directly above the piers and catenary pillars (case1), at the center of the pillar stall and directly above the piers (case2), the center of the piers gear and directly above the pillars (case3), and at the center of both pillars and piers (case4). The research results show that the voltage response of the overvoltage wave generated by the catenary at both ends of the signal equipment at the position of case3 reaches l50kV, and the amplitude is more than twice that of the other positions, it is recommended to remove the signal equipment at this position no matter how …

Research on Broadband Modeling of Transmission Line Tower Based on Vector Matching Method

Authors

Nianwen Xiang,Jiawei Ni,Shulai Wang,Yifan Ke,Yeshou Hong,Jiahua Lei

Published Date

2023/5/12

At present, the multi-wave impedance model of the tower widely used in lightning protection analysis can not reflect the difference of the induced overvoltage of the transmission lines. Therefore, it is of great significance to carry out the transient modeling of lightning tower. This paper first deduces the fitting process of rational function, then selects the 8th order vector to fit the frequency response of the tower numerical model, and establishes the tower broadband equivalent circuit model based on the passive network synthesis theory and the pole-residue. Then based on CDEGS and ATP-EMTP joint simulation, the validity of the broadband modeling method is verified. Finally, the accuracy and engineering practice value of the broadband model are further verified by the scaled tower experiment.

Multiple wind turbines shielding model of lightning attractiveness for mountain wind farms

Authors

Jiayi Nie,Nianwen Xiang,Kejie Li,Weijiang Chen

Journal

Electric Power Systems Research

Published Date

2023/11/1

In this study, a lightning attractiveness assessment method was proposed for mountain wind farms (WFs). A full-size wind turbine (WT) model accounting for terrain topography was established. Then, the lightning collection area (LCA) of WTs was calculated using the self-consistent leader inception and propagation model (SLIM). Finally, a quantitative relationship between terrain structure and the LCA of a WT was obtained, and a shielding model was incorporated to realize differentiated lightning attractiveness assessment of WFs. Results showed that higher terrain height and steeper ground slope angle both increase the size and the height of the LCA, meaning that lightning attractiveness can vary because of terrain differences, even for WTs with the same elevation. The influence of ground slope angle on the LCA showed a saturation trend. The variation of the LCA was analyzed based on the distortion effect of …

See List of Professors in Nianwen Xiang University(Hefei University of Technology)

Nianwen Xiang FAQs

What is Nianwen Xiang's h-index at Hefei University of Technology?

The h-index of Nianwen Xiang has been 9 since 2020 and 11 in total.

What are Nianwen Xiang's top articles?

The articles with the titles of

An Analytical Carrier Recombination Turn-off Transient Model for High-Voltage IGBTs

Temperature evolution characteristics of stem root during dark period in positive long spark discharge

An Analytical Temperature-Dependent Turn-off Model for High-Voltage Field-Stop IGBTs Considering the Influence of Drive Circuit

Short Circuit Fault Characteristics of Low Frequency AC Transmission System Based on Modular Multilevel Matrix Converter

Nonlinear evolution of space synthetic electric field in positive DC corona mode transition

Research on Lightning Intrusion Wave Characteristics in Converter Station of Flexible Low Frequency Transmission System

Numerical simulation and experimental verification of plasma jet development in gas gap switch

Study on the discharge and defect characteristics of the binding wire to the insulated conductor in the distribution network

...

are the top articles of Nianwen Xiang at Hefei University of Technology.

What are Nianwen Xiang's research interests?

The research interests of Nianwen Xiang are: lightning protection, EMC, Electromagnetics

What is Nianwen Xiang's total number of citations?

Nianwen Xiang has 411 citations in total.

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