The Proceedings of the 17th Annual Conference of China Electrotechnical Society

Inhaltsverzeichnis

1. Frontmatter

2. Magnetic Core Design for CRAFT NNBI Core Snubber

   Bo Liu, Zhimin Liu, Caichao Jiang, Sheng Liu, Shiyong Chen, Junjun Pan, Chundong Hu, Yuanlai Xie

   Abstract

   The CRAFT project is a preliminary technology verification facility for Chinese next-generation magnetic nuclear fusion experimental device. The neutral beam injection system, as an important device for tokamak plasma current drive and auxiliary heating, is an important part of the CRAFT project. The core snubber is an important protection device to avoid breakdown damage during the operation of the neutral beam source. It can effectively suppress the surge current, absorb the arc energy, and weaken the EMI impact on nearby equipment. In this paper, the installation space and operating state of the core snubber are used as the initial conditions, and the core design of the core snubber is completed with the FBO method. Finally, the core parameters that meet the requirements of the physical scheme are obtained. In addition, by comparing the parameters of the four magnetic core materials to be selected, the silicon steel material with larger magnetic flux density variation and better square shape is selected as the magnetic core winding material of the snubber.

3. Research on Application of Split Reactance Type FCL in Distribution Network with DG

   Teng Chi, Zhifeng Zhang, Rongze Niu, Mingming Xu, Qixin Guo, Xinxin He, Qingpeng Zeng

   Abstract

   With the massive access of distributed generations (DGs) in the distribution network, the structure of distribution networks becomes more complex, resulting in an increasing short-circuit currents. The limitation of short-circuit currents becomes an urgent problem to be solved for distribution networks. In this paper, based on the analysis of the network structure and short-circuit fault characteristics of distribution networks with DGs, the fault current limiter (FCL) is introduced to solve the problem of sudden increase of short-circuit currents. Firstly, a typical model of distribution network with DG is established, and fault characteristics and short-circuit current distribution are analyzed. Secondly, a split reactance type FCL is proposed to analyze the current limiting characteristics. Finally, a distribution network system model with split reactance type FCL is established, and current limiting analysis is carried out. The research results show that the split reactance type FCL can realize the fault current limiting of the distribution network with DG well and improve the reliability of the grid operation after the DG access.

4. Effects of Pulse Width and Frequency on the Methane-Air Nanosecond Pulsed DBD Plasma-Assisted Combustion

   Wenjing Meng, Bin Li, Tong Chen, Jie Pan, Shaohua Qin

   Abstract

   Nanosecond pulsed DBD plasma-assisted combustion is an emerging way to improve the utilization of fuel and decrease the emission of greenhouse gas by taking advantage of plasma enhancement effects based on non-equilibrium characteristics and selective excitations of nanosecond pulsed DBD plasmas. Using the homemade model of pulsed DBD plasma and Chemkin-Pro software, the influences of changing pulse width and frequency on premixed methane-air combustions assisted by nanosecond pulsed DBD plasmas are discussed. The simulation results indicate that the plasma technology can significantly improves combustion efficiencies by adjusting the pulse parameters.

5. Research on Global Temperature Rise Characteristics of Hysteresis Motor Based on Dynamic Loss Model

   Shaolin Li, Qiwei Xu, Qian Wang

   Abstract

   Hysteresis motors are widely used in gyroscopes due to their self-starting capability, high starting torque and simple geometry, and are key components to ensure the normal on-orbit operation of satellites or launch vehicles. The drift caused by the temperature change will have a great impact on the accuracy of the instrument, so it is necessary to study the global temperature rise of the hysteresis motor. Motor loss is the main heat source in motor operation, and improving its calculation accuracy is the premise to ensure the accuracy of global temperature rise. However, different from the traditional motor, the nonlinearity of the hysteresis material of the hysteresis motor and the complexity of the starting process make its analysis difficult. This paper firstly proposes a method to determine the working hysteresis loop through Preisach model. Based on this, the loss calculation model of the hysteresis motor is deduced and verified by simulation. Finally, the result of loss model is used as the heat source, and the global temperature rise characteristics of the motor are studied. The temperature distribution rules and design points of key structures are obtained, which has certain reference significance for the thermal design of hysteresis motors.

6. Research on Power Flow Algorithm of Distribution Network with Distributed Generation

   Meng Meng Zhou, Mao Song Zhang, Jun Tao, Xian Wu, Hua Ying Zhang

   Abstract

   Distributed generation in distribution network will increase the complexity of power flow calculation. So, this work proposes a three-phase power flow calculation, which combines the forward and backward method with the improved implicit Zbus Gauss method. The distribution network's radiation network's power flow is calculated using the forward-backward approach. The auxiliary theorem of matrix splitting and matrix inversion is used to deal with the node admittance matrix in the implicit Zbus Gaussian method. The improved implicit Zbus Gaussian method accustomed to deal with the power flow of the ring network. According to the calculated data, the three-phase voltage, injection current and injection power of the boundary nodes of the radiation network and the ring network are continuously corrected. When dealing with the PV node, the Davenin equivalent circuit is used to calculate the reactive power correction of the PV node. Finally, the IEEE33 – bus unbalanced distribution system is tested.

7. Research on Non-contact Measurement Method of Conductor Length of Low Voltage Overhead Lines Based on Small Target Recognition and Location

   Ziwen Cai, Yun Zhao, Yong Xiao, Yuxin Lu, Peng Wang

   Abstract

   In low voltage distribution network, the conductor length of overhead line is needed to build the physical topology and estimate the electrical parameters. However, the overhead lines are erected on the pole and the line trend is complicated, so the conductor length is not easy to be measured directly. This paper presents a non-contact measurement method of overhead conductor length based on insulator target recognition and location by image processing. In the large scene image taken by unmanned aerial vehicle(UAV), the insulator targets on low voltage overhead line are small and have weak characteristics. We will partition the large scene image into manageable cutouts to avoid missed detection of the small insulator targets. The attention mechanism module with channel attention and spatial attention is introduced to give attention weight to the characteristic elements in the region of interest, so as to identify the small insulator targets quickly and effectively. On the basis of small insulator targets recognition, the relationship of coordinates in the UAV image system is established according to the machine vision principle. The longitude and latitude of the insulators and the conductor length of the overhead lines are estimated through the conversion relationship between coordinate systems. Finally, the experiments of the overhead line pictures taken by the UAV are carried out. Compared with the manually measured overhead conductor length, the results show that the method in this paper is effective and has high precision.

8. The Random Spatial Distribution of Pulsed Air Spark Discharge Path Under Needle-Plate Electrode Configuration

   Lei Han, Zhongjie Sun, Yang Xia

   Abstract

   The development of the streamer discharge has the characteristic of randomness. In this work, based on the statistical and digital image processing method, the effects of the applied voltage, pulse interval and discharge gap on the random path of the spark discharge are studied with a needle-plate electrode configuration. The measurements show that the distribution of the discharges path obeys normal distribution. By calculating its standard deviation, it is concluded that its randomness of the path decreases with the increase of applied voltage, increases with the increase of pulse interval, and increases with the increase of discharge gap. The experimental results indirectly verify that the randomness of spark discharge is affected by the space electron concentration and the applied electric field.

9. Preliminary Study on Parameters and System Efficiency of Capacitor Energy Storage Pulse Power Supply Based on Analytical Modeling Method

   Xing Li, Wenyi Ye, Xuzhe Xu, Rongyao Fu, Jiong Wang, Weidong Xu, Ping Yan

   Abstract

   The capacitive energy storage pulse power supply is the most mature and extensive power supply for electromagnetic drive system at present. The existing circuit simulation software model of electromagnetic drive system has some shortcomings, such as complex operation, weak analytical ability and programmable ability. In this paper, the analytical modeling and programming of electromagnetic drive system under synchronous triggering are carried out, which mainly includes four parts: power supply, load, circuit discharge process and motion process. The established analytical model is reliable and practical, and can be used for further output performance analysis. On the basis of the established model, the parameters of 270 kJ capacitor energy storage pulse power supply are scanned, analyzed and sorted, which provides an idea for the optimization design of power supply.

10. A Laminated Busbar Design for Multiple IGBT Modules Paralleling

    Feng Mu, Xun Ma, Guang Yang, Yanqing Zhang

    Abstract

    In order to improve the current capacity of the converters, IGBT multi-module parallel connection has been widely used due to its economy. The problem of current sharing among parallel modules has become a difficulty in the design of converter modules. Following a number of design principles and the circuit topology used in practical applications, a laminated busbar that can improve the current sharing characteristics of the system is designed in this paper, in which the total current exceeds 10kA. For half-bridge module and independent IGBT module, the theoretical analysis of the stray parameters of the IGBT commutation circuit with n paralleling is carried out. With power division, remote paralleling among legs and staggered paralleling within leg, the overall structure of busbar is established. The stray inductance values of the commutation circuit of the busbar before and after power division are compared through Q3D simulation. Besides, the stray inductances of the commutation circuits corresponding to several IGBT modules in the divided busbar are extracted, which shows the consistency of their parameters. Then, the static sharing characteristics of output current from the busbar are analyzed with Magnet simulation. Finally, the effectiveness of the laminated busbar design is verified by double-pulse test and inverter test.

11. Design of Multi-filar Wire-Helix Transmission Line with Large Slowing Coefficient

    Chaoran Chen, Rong Chen, Jianhua Yang, Xinbing Cheng, Jiuyuan Geng, Yunrui Yue

    Abstract

    In this article, the effect of structure on the transmission characteristics and impedance of a multi-filar parallel wire-helix transmission line is analyzed by simulation. Based on the simulation results, a transmission line with a large slowing coefficient is designed to ensure the transmission characteristics as much as possible. A five-filar wire-helix transmission line with 13.6 slowing coefficient, 13 Ω impedance and 200 ns transit time, was designed and processed according to the design. The experiment proves that the multi-filar wire helix transmission line can still maintain good transmission characteristics under the large slowing coefficient.

12. Vibration and Acoustic Noise Reduction of 8/6 Poles SRM on Stator Yoke

    Yuwei Zhu, Zhitong Liu, Bingqing Zhu, Shiwei Yan, Chuang Liu

    Abstract

    The Switched reluctance motor has the disadvantages of large torque ripple and obvious vibration due to its own salient pole structure and excitation method. Considering its application scenarios, it is necessary to suppress vibration and noise while meeting the performance indicators. Therefore, this paper designs a new type of stator yoke structure with simple structure and convenient processing. By changing the shape of the stator yoke, the radial magnetic flux density is weakened, thereby weakening the radial force, increasing the structure, increasing the natural frequency and reducing the electromagnetic vibration of the motor. Through the calculation of the magnetic field segmentation method, we know that thickening the stator yoke can effectively reduce the radial force. The vibration acceleration, noise and inherent vibration of the motor are simulated by Workbench. It proves the motor vibration effect of the thickened stator yoke and the proposed new stator yoke shape. Finally, it is verified by simulation that the proposed motor structure can achieve better vibration and noise reduction effects.

13. Rotor Strength Analysis and Design of High Speed Permanent Magnet Motor

    Shuangshuang Guo, Bo Zhao, Binglin Lu, Jun Wang, Jian Liu, Yukang Chu

    Abstract

    Aiming at the rotor strength problem of high speed permanent magnet synchronous motor (HSPMSM), a design method for maximum outer diameter of permanent magnet is proposed. Firstly, on the basis of mechanics of materials, the stress analytical model of HSPMSM rotor with anisotropic material is established. Then, the analytical model is verified by FEM. The error between finite element calculation and analytical method is small. Finally, taking a HSPMSM in which rated speed is 100000 r/min as an example, the design method of maximum outer diameter of permanent magnet is given. The maximum outer diameters of permanent magnets for two kinds of r sleeve materials are obtained. The results show that using carbon fiber sleeve can design larger rotor outer diameter than using alloy sleeve. The large outer diameter of the rotor is very effective in improving the power of the motor. The proposed method provides a basis for rotor design of HSPMSM.

14. Development of MPC High Voltage Nanosecond Pulsed Coaxial Plasma Igniter Drive Power Supply

    Weihua Chen, Tao Tang, Xuzhe Xu, Ping Yan, Cunxi Liu

    Abstract

    In this paper, a single-stage magnetic pulse power supply based on a single-stage magnetic pulse compression topology that omits the core reset circuit is proposed for the actual problem of coaxial plasma igniter drive power supply for aerospace vehicles. The main circuit includes the primary capacitor series resonant charging circuit, the pulse formation circuit and the magnetic switch pulse compression circuit, and the control circuit includes the IGBT driver circuit and the capacitor charging voltage feedback circuit. The main circuit of the pulsed power supply is modeled by PSpice software with saturated transformers and magnetic switching cores and built with a resonant frequency of 50 kHz and a switching frequency of 25 kHz. When the primary capacitor is charged at 500 V, the output voltage is 40 kV, the repetition frequency is 2 kHz. The results show that: when the voltage increases to 10.4 kV, the breakdown discharge forms a plasma; the experimental results under different inlet methods and flow rates show that the plasma igniter has a better discharge uniformity under the cyclone inlet, and the igniter discharge uniformity can be further improved by adjusting the flow rate.

15. Optimization of Thermoelectric Generation by Improved PSO MPPT Algorithm

    Rui Cheng, Lei Wang, Ziqi Zhou, Huaxiang Wang, Site Mo

    Abstract

    Generator (TEG) is a new energy power generation device that directly converts thermal energy into electrical energy. It is extremely important to use converters to achieve maximum power point tracking (MPPT) for its output [1]. In order to improve the output power and stability of thermoelectric power generation system, this paper proposes a maximum power point tracking (MPPT) method for thermoelectric power generation based on improved particle swarm optimization. The algorithm proposes methods such as adaptive learning factor and inertia weight on the basis of traditional particle swarm optimization. Through Matlab/Simulink simulation verification, the results show that compared with the traditional disturbance observation method and particle swarm algorithm, the improved particle swarm algorithm can quickly, stably and accurately track the temperature difference under the condition of constant temperature difference and dynamic temperature difference, improves the power generation efficiency. Finally, the actual measurement is carried out on the self-built thermoelectric power generation experimental platform. The experimental results show that after adding the MPPT control module, the turn-off time of the MOSFET is shortened, and the output power is improved and more stable.

16. Integrated Control Strategy for Wind Turbine and Hydraulic Turbine in Primary Frequency Regulation

    Qianjin Gui, Chengyuan Zhong, Qianjun Jiang, Jiachen Liu, Jingjing Wang, Zhi Li

    Abstract

    Under the background of large-scale entry of new energy like wind power and hydropower to the power grid, more and more attention has been paid to how to use the complementary characteristics of new energy output to improve the security and the power grid’s stability. In this paper, a control strategy of combined participation of wind turbines and water turbines in primary frequency regulation (PFR) considering the flexibility of standby is proposed. First, the appropriate frequency modulation reserve capacity according to the wind speed and the operation of the turbine is determined. At the initial stage of system disturbance, the fast power control capability of variable-speed wind turbine generator is used to provide PFR fast standby capacity, give full play to its advantages of quickly suppressing frequency change rate and reducing the maximum frequency deviation, and complement the inherent defects of the lagging time of primary frequency response of conventional hydropower and thermal power units and the water hammer effect of hydropower units. Subsequently, the hydropower units provide stable active power support. In the middle and later stages of disturbance, the coordination between the fan and the water turbine unit avoids the secondary frequency drop caused by the fan entering the speed recovery process, and reduces the maximum frequency deviation and response time of the system. The example analysis verifies that the frequency modulation control strategy proposed in this paper can quickly and effectively realize the frequency control under different load sudden increment.

17. Fault Diagnosis System of High Voltage Switch Cabinet Based on Multi-source Information Fusion

    Yaxing Qiao, Zhangyu Chen, Hongxi Le, Yiwen Gao, Haoming Zhao, Jingwen Ni

    Abstract

    Taking high-voltage cabinet as the research object, aiming at the complexity, fuzziness and uncertainty of the system, this paper establishes a fault diagnosis system for high-voltage cabinet based on D-S evidence theory. Firstly, several typical fault types of high-voltage cabinet are selected as the identification framework of the system in this paper. Secondly, a new BPA generation method is designed according to the correlation model between faults and symptoms and based on triangular fuzzy numbers. Then, the fusion of evidence theory is modified by the discount operation method. Finally, the BPA is transformed into a probability distribution, in which the maximum probability is the identified fault.

18. Bioimpedance Spectroscopy Measurement of HepG2 Liver Cancer Mice

    Tongyang Jin, Guoqiang Liu, Wenwei Zhang, Hui Xia

    Abstract

    Hepatocellular carcinoma is a malignant tumor and changes in electrical properties of tumors occur in the early stage, and the measurement of bioimpedance spectroscopy can help in the study of early detection of liver cancer. In this study, we measured the bioimpedance spectroscopy of tumor and organ tissues (liver, kidney and heart) at different growth periods using homemade electrodes in nude mice inoculated with HepG2 cells, and fitted the Cole-Cole electrical impedance characteristic equation using the least squares method. There are differences in the Cole-Cole characteristic parameters of tumors and organs, and it is possible to distinguish different tissues by the parameters. The electrical impedance of tumor tissues tended to decrease significantly with tumor growth, especially the low frequency parameter \({R}_{0}\), which was almost twice as high in the early stage as in the late stage. There is also a development pattern for other measured organ characteristic parameters.