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Simulation analysis of Microgrid Voltage Stability with Multi-induction Motor Loads

ELECTRIC power COMPONENTS AND SYSTEMS 2018年第5期46卷 560-569页

作者： Lin, Li Zhao, Xiaoyan Zhu, Jizhong Zhang, Xiangwu Yang, Ruirui Chongqing Univ Dept Power Syst & Automat State Key Lab Power Transmiss Equipment & Syst Se Chongqing Peoples R China China Southern Power Grid SEPRI Dept Power Syst Guangzhou Guangdong Peoples R China State Grid Nanyang Power Supply Co Dept Power Syst Nanyang Peoples R China Shanghai Invest Design & Res Inst Co Ltd Dept Power Syst Shanghai Peoples R China

This paper studies the voltage stability problem in microgrid with multi-induction motor (MIM) loads. Firstly, the dynamic coupling relationship between grid voltage and each motor load slip in microgrid with MIM loads is deduced based on the power balance theory of power system. Then, a multi-source and master slave control based microgrid model is built, where Matlab/Simulink software is used to analyze microgrid voltage stability under circumstances of MIMs superimposed starting and microgrid fault. Through simulation calculation and analysis, the measures to improve the voltage stability of microgrid with MIM loads are proposed. According to the simulation results, the interaction between MIM loads has great influence on microgrid voltage stability. In addition, the critical cleaning time (CCT) of series connected master slave control based microgrid is affected by the distance between three phase short circuit fault location and the induction motor load location, as well as the distance between fault location and main control unit. The microgrid voltage stability can be effectively improved by applying methods of superimposed starting strategy and fast motor cutting strategy. The conclusion provides a reference for voltage stability research and control of the microgrid with MIM loads.

关键词： ELECTRIC potential VOLTAGE regulators MICROgridS ELECTRIC power distribution ELECTRIC power production

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Systematic controller design for digitally controlled LCL-type grid-connected inverter with grid-current-feedback active damping

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INTERNATIONAL JOURNAL OF ELECTRICAL power & ENERGY SYSTEMS 2019年第Sep.期110卷 642-652页

作者： Zhu, Donghai Zou, Xudong Zhao, Yingying Peng, Teng Zhou, Shiying Kang, Yong Huazhong Univ Sci & Technol Sch Elect & Elect Engn State Key Lab Adv Electromagnet Engn & Technol Wuhan Hubei Peoples R China State Grid Anhui Elect Power Co Ltd Econ Res Inst Hefei Anhui Peoples R China China Elect Technol Grp Corp Smart City Res Inst Shenzhen Peoples R China Wuhan Second Ship Design & Res Inst Wuhan Hubei Peoples R China

An LCL filter is commonly used in grid-connected inverter to attenuate the switching harmonics;nevertheless, the stability problems will arise in the grid current control if the resonance of LCL filter is not properly damped. High pass filter-based grid current feedback active damping is an effective solution to solve the aforesaid problem. However, for systems with digital control, the system may exhibit non-minimum phase system characteristics due to the control delay effect, which will affect the system stability. Moreover, the frequency responses of current controller parameters and active damping parameters are coupled. Therefore, to ensure the system stability and good dynamic performance, the current controller parameters and active damping parameters should be designed together, considering the control delay effect. For this issue, a systematic controller design method is proposed for the digitally controlled LCL-type grid-connected inverter with grid-current-feedback active damping. With the proposed method, the satisfactory regions of the control parameters for satisfying the system specifications can be obtained, from which the proper control parameters can be easily and quickly picked out, without the trial and error. Finally, the proposed design method is verified by the experiment.

关键词： Control delay grid-connected inverter grid current feedback active damping LCL filter Systematic controller design

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Research on The Secure Transmission Method of Terminal Upgrade Files based on Dynamic Encryption key

Research on The Secure Transmission Method of Terminal Upgra...

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Electronic Information Technology and Computer Engineering (EITCE), International Conference on

作者： Yilun Fu Feng Zhai Wei Cen Yanjie Zhang Baofeng Li China electric power research institute Beijng China State Grid Key Laboratory of Power Industrial Chip Design and Analysis Technology Beijing Smart-Chip Microelectronics Technology Co. Ltd. Beijng China

ISBN: (数字)9781728135847

ISBN: (纸本)9781728135854

In order to improve the secure transmission capability of terminal upgrade files, we proposed a secure transmission method of terminal upgrade files based on dynamic encryption key. This method realized the access control of terminal upgrade file by using no proxy key publishing protocol, designed the dynamically symmetric key for the terminal upgrade file. The encoding calculation of terminal upgrade files in the process of secure encryption is carried out based on bilinear mapping method. We scrambled and rearranged the terminal upgrade files according to the intensity of plaintext attack, then adopted the random linear coding method to encrypt the terminal upgrade files by dynamic symmetric key and realize the secure transmission for the files. Simulation results show that this method can effectively improve the security transfer performance of upgrade files, and can meet the requirements of current business applications.

关键词： Heuristic algorithms Encryption Protocols

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Evolutions of guide vane moment of a pump-turbine during runaway transient process after pump trip 29

Evolutions of guide vane moment of a pump-turbine during run...

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29th IAHR Symposium on Hydraulic Machinery and Systems (IAHR)

作者： Yang, Z. Y. Cheng, Y. G. Xia, L. S. Meng, W. W. Gao, L. W. Dai, Y. X. Wuhan Univ State Key Lab Water Resources & Hydropower Engn S Wuhan 430072 Peoples R China Wuhan Univ Minist Educ Ministerial Key Lab Hydraul Machinery Transients Wuhan 430072 Peoples R China China Ship Dev & Design Ctr Wuhan 430064 Peoples R China State Grid Xin Yuan Co LTD Baishan Pumped Storage Power Stn Jilin 132013 Jilin Peoples R China

The collision of guide vanes with runner of a pump-turbine during transient processes is rarely seen in pumped-storage power stations, but the consequence is serous when happens. To investigate the reason of a case of such an accident, we analyse the evolution rules of guide vane moment during the runaway transient process after a pump trip of a prototype pumped-storage system by using 1D-3D method. First the histories of macro parameters such as flow rate, rotational speed and runner moment and trajectory of working condition point are given. Secondly, the difference of guide vane moment under different working conditions is analysed, and the fluctuation components are decomposed by frequency domain analysis. Finally, the main factors affecting the fluctuation of guide vane moment are obtained by comparing pulsation and flow patterns. The results show that, due to different flow structures in different working conditions, there is a significant difference in the characteristics of guide vane moment, which affects the closing and opening trend of guide vanes in different positions. In contrast, the pulsation amplitudes of guide vane moment in no-load mode are the largest, followed by the pump braking mode, and those in the turbine and pump mode are smallest. The maximum guide vane moment is smaller than the design moment of guide vane fastening device during the transient, but it reaches 85.7% of the design value.

关键词： Pumps

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Research on Dual-Mode Communication Technology Based on power Line Carrier and Micro power Wireless

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Journal of Physics: Conference Series 2021年第1期2025卷

作者： Yan Long Yongli Chen Xudong Zhang Deyong Xiao Zheng Li Xiaoke Tang State Grid Key Laboratory of Power Industrial Chip Design and Analysis Technology Beijing Smart-Chip Microelectronics Technology Co. Ltd Beijing 100192 China Beijing Engineering Research Center of High-Reliability IC with Power Industrial Grade Beijing Smart-Chip Microelectronics Technology Co. Ltd Beijing 100192 China State Grid Hebei Electric Power Co. Ltd Shijiazhuang 050000 China

At present, the power meter reading system mainly uses the single power line carrier meter reading mode or the single micro power wireless meter reading mode. Due to the disadvantages of the two modes, the single meter reading mode can not meet the meter reading under different environmental conditions. In order to improve the success rate of communication, this paper puts forward the dual-mode communication technology of power line carrier and micro power wireless integration, which is based on the power line carrier It overcomes the defects of single meter reading mode and improves the real-time performance, reliability and success rate of meter reading.

关键词：

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Performance analysis of lora modulation with residual frequency offset 4

Performance analysis of lora modulation with residual freque...

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4th IEEE International Conference on Computer and Communications, ICCC 2018

作者： Tang, Xiaoke Li, Hongqiang Zhang, Yubing Zhao, Xu State Grid Key Laboratory of Power Industrial Chip Design and Analysis Technology Beijing Smart-Chip Microelectronics Technology Co. Ltd. Beijing100192 China

ISBN: (纸本)9781538683392

The rapid development of Internet of Things (IoT) puts forward much requirements for wireless communication technology. Low power Wide Area Networks (LPWAN) are designed for low bandwidth, low power, long range and large number of connected IoT applications. As one of the LPWAN, Low power Long Range Transceiver (LoRa) described as a Frequency Shift Chirp Modulation (FSCM), is widely concerned and studied. This paper analyzes the physical layer of LoRa, presents a basic mathematical signal processing model, and proposes a demodulation algorithm based on Fast Fourier Transform (FFT). The simulation performance of the demodulation algorithm is compared with the theoretical performance one of quadrature modulation incoherent detection. The results show that the performance derived through these two approaches is consistent. In addition, the performance of LoRa system with residual frequency offset under different spread factor (SF) is analyzed, and verified that the performance of the system decreases with the increase of SF. So we have to adopt better algorithm to correct frequency offset, otherwise the coverage will decrease significantly. © 2018 IEEE.

关键词： Wide area networks

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Distributed Active Damping for Harmonic Instability Suppression in the Multi-paralleled grid-connected Inverter System 45

Distributed Active Damping for Harmonic Instability Suppress...

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45th Annual Conference of the IEEE Industrial Electronics Society (IECON)

作者： Wang, Shunyu Cao, Wu Liu, Kangli Kang, Haotian Zhao, Jianfeng Shi, Chao Song, Jing Southeast Univ Sch Elect Engn Nanjing Peoples R China Southeast Univ Jiangsu Prov Key Lab Smart Grid Technol & Equipme Nanjing Peoples R China China Energy Engn Grp Jiangsu Power Design Inst Co Ltd Nanjing Peoples R China NR Elect Co Ltd Nanjing Peoples R China

ISBN: (纸本)9781728148786

Aiming at the harmonic instability problem of multi-paralleled grid-connected inverter system, which is caused by the interaction among the fast inner current or voltage control loops of inverters and grid impendence, distributed active damping is proposed in this paper. This approach is based on the grid voltage feedforward strategy and increase the damping of the global admittance (GA), which effectively improves the system stability. One of the advantages of this approach is that when some of the active damping fail to work, the remaining active damping can still maintain the system stability. Another is the employment of a second-order lag corrector which can alleviate the influence of the ignorance the prediction component and improve the characteristic of inverter output admittance at the harmonic controlled frequencies. Simulations are carried out and the results verify the effectiveness of the proposed method.

关键词： harmonic instability problem distributed active damping grid voltage feedforward strategy second-order lag corrector global admittance

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Responsibility Identification for Harmonic Instability in grid-connected Inverter-Based power System with Multi- Point of Common Coupling 45

Responsibility Identification for Harmonic Instability in Gr...

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45th Annual Conference of the IEEE Industrial Electronics Society (IECON)

作者： Wang, Shunyu Cao, Wu Liu, Kangli Kang, Haotian Zhao, Jianfeng Wang, Zhenquan Song, Jing Southeast Univ Sch Elect Engn Nanjing Peoples R China Southeast Univ Jiangsu Prov Key Lab Smart Grid Technol & Equipme Nanjing Peoples R China Jiangsu Power Design Inst Co Ltd China Energy Engn Grp Nanjing Peoples R China NR Elect Co Ltd Nanjing Peoples R China

ISBN: (纸本)9781728148786

Harmonic instability problem, caused by the interaction between the inner control loops of inverters and the grid impendence, has drawn much attention in recent years. Some studies have been carried out to analyze the stability in systems with multi-paralleled grid-connected inverters and multi-point pf common coupling (multi-PCC). However, the identification of the most responsible unit for the harmonic instability in a power system with multi-PCC has not been fully discussed. An identification method is proposed in this paper based on the sum type impendence-based stability analysis method. Based on the stability analysis from the lower bus level to the higher bus level, the sequence of this proposed identification procedure is inverse, which is from the higher bus level to the lower bus level until to the unit that can not be divided for the instability. Simulations results verify the effectiveness of the proposed method.

关键词： harmonic instability problem multi-bus power system grid-connected inverters identification procedure impendence-based stability analysis

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An Improved Security Chip Communication Rate Setting Method

An Improved Security Chip Communication Rate Setting Method

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International Conference on Information Systems and Computer Aided Education (ICISCAE)

作者： Liu Jia Qingqin Fu Zhengquan Ang Pingjiang Xu Yuhua Lu Zhaoqin Liang Jiahui Yuan Rui Nie Beijing Smartchip Microelectronics Technology Co. Ltd. Beijing Electric Power High Reliability Integrated Circuit Design Engineering Research Center Beijing China Beijing Aerospace Flight Control Center Beijing China Beijing Smartchip Microelectronics Technology Co. Ltd. Key Lab of Power Grid Design and Analysis State Grid Corporation of China Beijing China

ISBN: (数字)9781728130668

ISBN: (纸本)9781728130675

This paper analyzes the shortcomings of two setting methods which is commonly used in security chip communication rate, and proposes an improved setting method. The basic communication rate instruction parameters are set in a security chip for setting the communication rate in different communication modes. The interface device sends the communication rate instructions to the security chip. The security chip executes the communication rate instructions so as to complete the setting of the communication rate. This method can switch the communication mode freely, so it can be applied to diversified application scenarios.

关键词： Protocols Authentication Switches Integrated circuits Conferences

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An ultra-low power robust CMOS temperature sensor with an inaccuracy of ±0.7°C from-40°C to 85°C

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IEICE ELECTRONICS EXPRESS 2019年第16期16卷 20190381-20190381页

作者： Hu, Yi Hou, Jiali Zhang, Jianyun Zhang, David Wei He, Yang Fudan Univ State Key Lab ASIC & Syst Sch Microelect Shanghai 200433 Peoples R China Beijing Smart Chip Microelect Technol Co Ltd State Grid Key Lab Power Ind Chip Design & Anal T Beijing 100192 Peoples R China

An ultra-low power robust CMOS temperature sensor is presented for RFID. The BJT-based sensor employs a calibrated hybrid ADC, which combines a coarse 5-bit SAR conversion with a fine 9-bit delta-sigma conversion. For the purpose of being robust, an error correction method is proposed in this paper, which can calibrate the SAR errors caused by power supply and mismatch. A smart clock generator is also proposed to adapt the change of PTAT bias current, which provides the integrators more settling time in low temperature with low bias current and makes the delta-sigma ADC faster in high temperature to reduce the error caused by leakage. The sensor has been implemented in a 130 nm CMOS process. After a one-point temperature trimming, the sensor has a resolution of 0.015 from -40 degrees C to 85 degrees C, and only consumes 10 mu A from 1.5 V supply.

关键词： ultra-low power temperature sensor smart clock generator calibration

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