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2019 International Conference on Civil Engineering, Environment Resources and Energy Materials, CCESEM 2019

作者： Gao, Xiang Han, M.M. Zhang, X.Y. Cai, Z.Y. Wang, Fang Pang, M.X. Qi, J.H. Beijing Key Lab. of Agric. Product Detection and Control of Spoilage Organisms and Pesticide Residue BeijingUniversity of Agriculture Beijing102206 China Francethe Teaching Group of Food Chemistry Faculty of Food Science and Engineering Beijing University of Agriculture Beijing102206 China Beijing Innovation Consortium of Swine Researeh System Beijing102202 China Graduation Design of the Practical Training Program Cross-Cultivation of High-Level Talents in Beijing Colleges and Universities 2018 China

In this thesis, the chemical properties of chestnut shell pigments were mainly studied. Through a series of pigment stability experiments, it could be learned that the pigment of chestnut shell was sensitive to different pH and heat, stable to light, and had certain tolerance to oxidant H2O2 and reducing agent ascorbic acid. Mn2+ and Zn2+ had certain enhancement effects on color of the pigments. Cu2+, Fe2+, Fe3+ and Al3+ could destroy the stability of pigment, and caused precipitate. The pigment was also stable to the commonly used as food additives. © Published under licence by IOP Publishing Ltd.

关键词： Fruits

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Study on corruption bacteria in Beijing sausages

Study on corruption bacteria in Beijing sausages

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2019 International Conference on Civil Engineering, Environment Resources and Energy Materials, CCESEM 2019

Low-temperature meat products are very popular, but due to the characteristics of processing technology, there are still some heat-resistant microorganism residues after sterilization, which lead to its extremely vulnerable to corruption and short shelf-life. The spoilage discipline and mechanisms of Beijing sausages were summarized on the basis of spoilage bacteria isolation, identification and analysis. The main results were as follows: by using method of 16S rDNA sequence analysis, the main spoilage bacteria which isolated and identified from Beijing sausages were Pseudomonas sp, Staphylococcus sp, and Brochothrix sp. By denaturing gradient gelelectrophoresis(PCR-DGGE) analysis, there were 13 kinds of the spoilage bacteria of Beijing sausages, and Pseudomonas sp was the main spoilage bacteria. © Published under licence by IOP Publishing Ltd.

关键词： Bacteria

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Research on the fault calculation of AC-DC interconnected system under asymmetrical fault conditions

Research on the fault calculation of AC-DC interconnected sy...

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International Conference on Power system Technology (POWERCON)

作者： Yichao Zhu Chongra Liu Qinghua Si Gengyin Li State Key Lab. for Alternate Electrical Power System with Renewable Energy Source North China Electric Power University Beijing China Platform Development for Stability Control Station Divison NARI Technology Development Limited Company Nanjing China

A numerical model of fault calculation for AC-DC interconnected system under asymmetrical fault is proposed. It involves two converter models that work effectively under asymmetrical fault. Firstly the article establishes a converter model that based on switching function. In which HVDC system is substituted as sequence impedance in the AC system. The article proposes another converter model that based on the power factor of converter. In which HVDC system can be substituted as power source in the AC system. By simplifying the dynamic characteristics of the control system of HVDC, the numerical model of control system is proposed, and the circuit model of HVDC system is established. Iterative algorithm is used to solve the fault system. The simulation results and calculation results are compared under several fault conditions, and the applicability of the model and switch function is discussed. Some further researches are carried out based on the numerical model.

关键词： Switches Mathematical model Firing HVDC transmission Numerical models Harmonic analysis

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A Novel Triple Capacitor Multi-Level Submodule Mmc Topology with Fault Current Clearing Capability

SSRN

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SSRN 2023年

作者： Sun, Yinfeng Jia, Guobin Hao, Jiaqi Lu, Mingzhi Li, Guoqing Wang, Zhenhao Wu, Xueguang Modern Power System Simulation Control and Green Energy New Technol. Key Lab. The Ministry of Education Northeast Electric Power Univ. Jilin132012 China State Grid Smart Grid Research Institute Beijing China

In the high voltage direct current system based on modular multilevel converter (MMC-HVDC), the half-bridge submodule (HBSM) has become the preferred submodule for significant projects due to its convenient control and low cost. However, the DC shortcircuit protection performance of MMC-HVDC will seriously restrict its development in areas such as overhead lines, high voltage, and large capacity. This article proposes a triple capacitor multi-level submodule (TCMSM) based on a modular multilevel converter with DC fault-blocking capability. It utilizes at least one-third of the module capacitance in the bridge arm to reverse, suppress the DC fault current and turn off the diode. At the same time, the unidirectional conductivity of the diode can also prevent arc reignition at the fault point. The article also conducted in-depth research on the DC short-circuit fault elimination mechanism of this topology, and compared its performance with other topologies. Through analysis, it can be concluded that TCMSM reduces the initial investment and operating costs by reducing the number of devices inside the module while possessing the fault current blocking ability. Finally, MATlab.Simulink was used to simulate and verify the proposed new topology, and its performance was analyzed. © 2023, The Authors. All rights reserved.

关键词： Topology

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Model Predictive control with Reach-avoid Analysis

arXiv

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arXiv 2023年

作者： Ren, Dejin Lu, Wanli Lv, Jidong Zhang, Lijun Xue, Bai State Key Lab. of Computer Science Institute of Software CAS Beijing China University of Chinese Academy of Sciences Beijing China National Engineering Research Center of Rail Transportation Operation and Control System Beijing Jiaotong University Beijing China

In this paper we investigate the optimal controller synthesis problem, so that the system under the controller can reach a specified target set while satisfying given constraints. Existing model predictive control (MPC) methods learn from a set of discrete states visited by previous (sub-)optimized trajectories and thus result in computationally expensive mixed-integer nonlinear optimization. In this paper a novel MPC method is proposed based on reach-avoid analysis to solve the controller synthesis problem iteratively. The reach-avoid analysis is concerned with computing a reach-avoid set which is a set of initial states such that the system can reach the target set successfully. It not only provides terminal constraints, which ensure feasibility of MPC, but also expands discrete states in existing methods into a continuous set (i.e., reach-avoid sets) and thus leads to nonlinear optimization which is more computationally tractable online due to the absence of integer variables. Finally, we evaluate the proposed method and make comparisons with state-of-the-art ones based on several examples. Copyright © 2023, The Authors. All rights reserved.

关键词： Model predictive control

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Leak point localization systerm for closed vessel based on infrared image processing

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Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument 2010年第8 SUPPL.期31卷 233-236页

作者： Zhao, Ling Wang, Tao Peng, Guangzheng Zhao, Tong Complicated System of Intelligent Control and Decision Key Lab. of Education Ministry School of Automation Beijing Institute of Technology Beijing 100081 China

In this paper, a device for closed vessel's leaking localization is introduced based on infrared image processing. After the infrared thermography captured multi-frame infrared images of the closed vessel with cooling gas, each frame of the ROI region is processed by Gauss filtering. The suspected leak points are detected by hough circle detection method after their edges in the ROI are extracted by using canny edge operator. Finally, the appearance probability of the suspected leak point is used to determine a leaking point. Experiments show that the proposed method overcomes the disadvantage of infrared image's higher level noise effectively and is able to accurately localize the leak points.

关键词： Infrared imaging

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Research on Low Voltage Ride through and Reactive Power Support of Hydrogen Production Power Supply

Research on Low Voltage Ride through and Reactive Power Supp...

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Smart Power & Internet Energy systems (SPIES), International Conference on

作者： Mingqi Zhang Ruitong Liu Kui Wang Kai Sun Qinglai Guo Yongdong Li Dept. of Electrical Energineering State Key Lab. of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China State Grid Liaoning Electric Power Co. LTD. Electric Power Research Institute Shenyang China

Hydrogen energy, a type of green secondary energy, has attracted much attention in recent years. The production of hydrogen by water electrolysis is less harmful to the environment and makes it possible to obtain hydrogen with a high degree of purity. But it requires a lot of electricity and is expensive. Installed capacity and the share of electricity generation from new energy sources have increased recently. The "double high" trend in the power system is becoming apparent. The combination of new energy power generation and hydrogen production by water electrolysis can not only promote the absorption of new energy power generation, but also reduce the cost of hydrogen production. The conventional thyristor power supply system for hydrogen production has low power factor and poor harmonic performance, which cannot meet the requirements of the new power system. Hydrogen production power supply based on fully controlled devices is gradually becoming mainstream. In this paper, the low voltage ride through capability and the reactive power support function for the power grid of hydrogen production power supply based on fully controlled devices are verified by simulation. For both symmetrical and asymmetrical faults, the hydrogen production power supply can ride through the fault.

关键词： Performance evaluation Reactive power Power supplies Hydrogen Production Voltage Power grids

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Low-carbon Economic Dispatch of Integrated Energy system Considering Hydrogen Mixing in Natural Gas Pipeline

Low-carbon Economic Dispatch of Integrated Energy System Con...

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IEEE Conference on Energy Internet and Energy system Integration (EI2)

作者： Dong Xie Lihong Kang Yanbinz Jia Hao Chen Feng Tian Yun Bai Baifu Zhang Xuan Cui State Grid Shaoxing Power Supply Company Shaoxing China Shanxi Key Lab. of Power System Operation and Control Taiyuan University of Technology Taiyuan China State Grid Shanxi Electric Power Company Taiyuan Power Supply Company Taiyuan China

ISBN: (纸本)9781665434263

With the rapid growth of the penetration rate of renewable energy, the construction of Integrated electricity-natural gas system (IEGS) has important economic and environmental significance. Power-to-gas (P2G) technology, as a new energy conversion and storage method, provides an important way for wind power consumption. Due to the limited local consumption of hydrogen energy and difficulty in exporting, this paper proposes an IEGS optimal scheduling model that considers hydrogen mixing in natural gas pipeline and aims at the lowest system operating cost. After the verification of the improved IEEE 14-node power network and the Belgian 20-node natural gas network coupling system, the operation mode of the IEGS proposed in this paper can expand the hydrogen demand, increase the hydrogen transmission capacity, and promote wind power consumption. At the same time, it can achieve carbon emission reduction and improve the economics of system operation.

关键词： Renewable energy sources systems operation Hydrogen Pipelines Energy conversion Carbon dioxide system integration

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Research on Lightweight Small Object Detection Method with Fusion Attention Mechanism

Research on Lightweight Small Object Detection Method with F...

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Chinese Automation Congress (CAC)

作者： Haowen Dai Bingyou Liu Guoyang Wan Jingjing Qi Luanfei Wan School of Electrical Engineering Anhui Polytechnic University Wuhu China The Key Lab. of Advanced Perception and Intelligent Control of High-End Equipment Ministry of Education Anhui Polytechnic University Wuhu China Anhui Dar Intelligent Control System Co. Ltd. Wuhu China Wuhu Institute of Technology Wuhu China

In the task of small object detection, due to the relatively small size of the objects, complex situations such as occlusion and overlap may arise in high-density scenes. These factors can significantly increase the issues of missed detections and false detections in object detection tasks. To address the aforementioned issues, this paper proposes a lightweight small object detection model, YOLOv5s-MGC. Firstly, we introduce an improved Mobilenetv3 network to replace the backbone network of YOLOv5s, aiming to improve the network's capability for effective feature extraction. Secondly, we incorporate the GSConv module into the feature fusion network to reduce model parameters and strengthen the network's ability in fusing feature information. Finally, we have integrated Convolutional Block Attention Module (CBAM) at the forefront of the detection heads, achieving the fusion of fine-grained features. We assessed our approach on the openly accessible dataset ‘SHWD’ and contrasted the results with the baseline YOLOv5s and various SOTA object detection models. Precisely, our method attains an accuracy of 91.1%, exceeding the baseline module by 1.6%. Furthermore, the module size is reduced to 1.97MB and it achieves a 52.4 FPS. In comparison to other prevailing algorithms, YOLOv5s-MGC enables efficient and accurate small object detection.

关键词：

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Partly-isolated four-port converter based on bidirectional full-bridge DC/DC converter

Partly-isolated four-port converter based on bidirectional f...

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IEEE Conference on Industrial Electronics and Applications (ICIEA)

作者： Xiaoqiang Lin Yanbing Jia Jinjie Tian Chunguang Ren Jinhao Wang Peng Wang Faheem Akher Chachar Tiejiang Yuan Xiaoqing Han Shanxi Key Lab. of Power System Operation and Control Taiyuan University of Technology Taiyuan China State Grid Electric Power Research Institute of Shanxi Province Taiyuan China Taiyuan China Department of Electrical Engineering Sukkur IBA University Sukkur Pakistan faheem

According to the analysis of the traditional multiport converter, a novel partly-isolated four-port converter topology is proposed. The proposed converter is combined by two boost converters and a bidirectional full-bridge DC/DC converter, which can realize bi-directional transfer of energy and isolated between ports, and it ensures the stability of photovoltaic power with a lithium battery energy storage system. Then the control strategies of proposed converter under different working modes are analyzed. Finally, the simulation of operating modes and the conversion between the modes are carried out to verify the feasibility of the new four-port converter.

关键词： control systems Power system stability Lithium batteries Load flow Topology Photovoltaic systems

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