Table of Content

30 June 2023, Volume 0 Issue 6

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Research & Analysis

Fault Diagnosis Method of Early Inter-Turn Short Circuit of Permanent Magnet Synchronous Wind Turbine Based on Attention Mechanism

ZHOU Kai, WANG Xiaodong, WANG Gang, LIU Guangwei, LIU Yingming

2023, 0(6):  1-8.  doi:10.16628/j.cnki.2095-8188.2023.06.001

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The stator current and voltage fluctuation caused by early inter-turn short circuit of permanent magnet wind turbine is weak, which makes fault identification difficult and prone to miscalculation. To solve this problem, the convolutional neural network and bidirectional long short-term memory network (CNN-BiLSTM) fault diagnosis method based on attention mechanism is proposed. The zero sequence components of generator current and voltage are taken as fault features, and the CNN and BiLSTM fault diagnosis models are used for feature self extraction. Attention mechanism is introduced to evaluate the weight of features at different time, and the weight of key features in fault diagnosis is strengthened based on this. The results of numerical examples show that the proposed method can realize the early inter-turn short circuit fault diagnosis of permanent magnet wind turbine generator, significantly improve the identification accuracy compared with traditional methods, and reduce the time spent in model training.

μPMU Multi-Objective Optimal Configuration Strategy for Microgrid Considering Node Failure Rate

SHI Zehui, MU Longhua

2023, 0(6):  9-17.  doi:10.16628/j.cnki.2095-8188.2023.06.002

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The dynamic behavior of microgrid is more complex than that of traditional power grid, so it is urgent to solve the problem of fault detection and location. The optimization configuration of micro phasor measurement unit (μPMU) in microgrid system is studied. A multi-objective optimal μPMU configuration strategy considering cost, node failure rate and redundancy is proposed. Based on the multi-objective function of the lowest installation cost, the highest sum of node failure rate and the highest observable redundancy, a multi-objective optimal configuration model is established according to the normal state of the system and the constraints of arbitrary line faults. The nondominated sorting genetic algorithm Ⅱ (NSGA-Ⅱ) is improved by differential evolution operator, and the improved algorithm is used to solve the model and select the optimal compromise solution. Based on the improved IEEE 30-node microgrid system simulation analysis, it is shown that the multi-objective optimal configuration strategy taking into account the node failure rate is feasible. The proposed strategy can effectively carry out the whole network visualized monitoring of the microgrid system and give consideration to the economy and accuracy.

Resonance Analysis and Suppression Strategy for Parallel Operation of Grid Connected Inverter

SHANG Yang, WANG Yongsheng, WEI Chao, HUANG Haihong

2023, 0(6):  18-22.  doi:10.16628/j.cnki.2095-8188.2023.06.003

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Aiming at the resonance risk of the parallel operation of multi grid connected inverters with LCL filter in weak pawe grid, the mathematical model of multi inverter parallel system is established. The resonance of multi grid connected inverter parallel system is analyzed. A new grid connected current feedback control strategy is adopted and the design parameters are optimized to improve the inverter phase and amplitude margins. The resonance of multi grid connected inverter parallel system can be effectively suppressed. Finally, two grid connected inverters are built in parallel on MATLAB/Simulink and experimental platform. The simulation and experimental results verify that the proposed strategy can be applied in the multi inverter parallel system.

Optimal Operation Method of CCHP System Based on Improved Following Thermal Load Mode

YIN Guangzhi, GUO Zhen

2023, 0(6):  23-32.  doi:10.16628/j.cnki.2095-8188.2023.06.004

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The combined cooling heating and power (CCHP) is an important way to improve the efficiency of energy intensive, deepen the transformation of energy system, and achieve the goal of “double carbon”goal. A CCHP system model including micro gas turbines, photovoltaic power supply, gas boilers and battery is simulated. Based on the common following thermal load mode and following electric load mode, an improved following thermal load mode is proposed. The proposed operation mode can effectively improve the cost-effectiveness and energy-effectiveness of system, and achieve a higher energy saving rate.

Research on IoT of Electrical Appliances Based on Data Transparent Transmission

WANG Jingjing, WU Guichu, LIANG Bumeng, ZHANG Wanqing, MA Shuaishuai, ZHOU Xingyu

2023, 0(6):  33-38.  doi:10.16628/j.cnki.2095-8188.2023.06.005

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To resolve the problems of data transmission protocols inconsistency, system integration difficulty, long R&D cycles and high R&D costs during Internet of things (IoT) upgrade for products, a highly operational, scalable, and portable software and hardware bidirectional interactive IoT data transmission method is proposed and implemented. Based on the ESP8266 Wi-Fi chip, the MQTT protocol, as well as EasyStudio message middleware platform, a highly compatible, efficient, and stable electrical IoT application system is designed and developed. According to the data messages obtained by the electrical appliance of the IoT and the test results of the opening and closing of the control appliances, it shows that the proposed method can realize the real-time, accurate and comprehensive collection, forwarding and storage of electrical data, as well as two-way communication for real-time control of hardware controllers, the rapid upgrading of IoT, data visualization of electrical appliances. It is of great practical significance for enterprises to save energy and reduce emissions.

Simulation Analysis and Experimental Verification of Mechanical Characteristics for Rocker Switches

SU Bin, HE Yubin, REN Wanbin, TIAN Shanmin, SHEN Huiyuan, PENG Meinan, MA Teng, HUANG Chaowen

2023, 0(6):  39-43.  doi:10.16628/j.cnki.2095-8188.2023.06.006

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Rocker switches is a commonly used hand-operated wall switch.In order to research the mechanical characteristics of the rocker switch,COMSOL Multiphysics finite element software is used to simulate the closing process of switch.Through the finite element simulation,the switching force is obtained and the reason of the closing bounce is clarified.The switching force curve and bounce waveform of the actual switch are obtained through experiments,and compared with the simulation results to verify the reliability of the simulation method.

Distribution System Technology

Design and Exploration of Integrated Energy System for Industrial Parks Based on Medium and Low Voltage AC/DC Distribution Networks

WU Fangzhu, TIAN Yuan

2023, 0(6):  44-50.  doi:10.16628/j.cnki.2095-8188.2023.06.007

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In order to solve the problems of low power transmission efficiency in AC distribution network, a comprehensive energy system configuration method is proposed based on AC/DC hybrid distribution network that integrates medium voltage and low voltage levels, which can improve the new energy consumption capacity and power supply reliability. Firstly, a two-level programming model of integrated energy service equipment configuration and daily operation economy is established. Then, the improved moth flame optimization algorithm is combined with CPLEX to solve the problem. Finally, the optimal integrated energy equipment configuration scheme is obtained under the given example, and the various costs under the traditional AC distribution network are compared and analyzed, which proves that the integrated energy system based on the AC/DC distribution network is more advanced and reliable.

Research on Multi-Station Integration Planning and Arrangement Scheme

LI Xiaoyun, LUO Zhongda, DING Xinyao, SUN Zhiyun, LU Xiaolong, TANG Ping, XU Yanfen, TANG Lisong

2023, 0(6):  51-57.  doi:10.16628/j.cnki.2095-8188.2023.06.008

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As an important element and a new type of infrastructure in the energy Internet, the multi-Station integration system will play an important role in the deep integration of energy and information in the future. An in-depth study was conducted on the planning and layout of the multi station fusion system, and a multi Station fusion system site selection and capacity optimization scheme based on the minimum cost of multi-dimensional load distance was proposed. Based on the specific situation of Hunan power grid, analysis was conducted and suggestions for the construction of the multi station fusion system in Hunan were given.

Research on Enterprise Electricity Consumption Prediction Based on Partial Least Squares Regression

HU Min, ZHANG Yuewei, GAO Xiaotian

2023, 0(6):  58-62.  doi:10.16628/j.cnki.2095-8188.2023.06.009

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With thedevelopment of power reform, the construction of electricity marketization has further accelerated. The analysis and prediction of electricity consumption have become the focus of attention for power supply enterprises and electricity consuming enterprises. Electricity consumption can also reflect the current operation status and development trend of enterprises, which is of great significance to production-oriented enterprises. However, the data of power consumption is less and the data accuracy is insufficient. The common machine learning methods are not suitable for this application. Therefore, the partial least squares (PLS) method is used to solve these problems. At the same time, the problem of high correlation between the acquired data can also be handled. Based on the PLS method, the regression model of enterprise electricity consumption prediction is established, and the validity and accuracy of the model are verified by the data simulation.

Differential Fault Security Protection Method for 5G Carrying Distribution Networks

GUO Lexin, HU Jiaxin, ZHOU Jianyong, WANG Tinghuang, XU Jian

2023, 0(6):  63-69.  doi:10.16628/j.cnki.2095-8188.2023.06.010

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The fifth generation (5G) wireless network not only provides a low-cost bearing scheme for the differential protection service of distribution network, but also poses a threat of wireless network attacks. Considering the issue of system collapse due to line tripping after external attacks invade the distribution network, a differential fault protection method for medium voltage DC distribution network is proposed. The proposed method can detect the external cyber intrusions on the adjacent lines of the distribution network where the physical fault occurs at the same time.The modal transformation is conducted to obtain the line mode and zero mode voltage of the current limiting reactor deployed by the system. The simulation results show that the proposed method has high sensitivity to high impedance faults and good protection performance, which can effectively improve the security of differential protection services in distribution networks in 5G wireless network environments.

Energy Efficieney Management

Energy-Saving Benefit Evaluation of Railway Traction Power Supply Based on Back-to-Back Converter

WU Mingliang

2023, 0(6):  70-74.  doi:10.16628/j.cnki.2095-8188.2023.06.011

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Regenerative braking power feedback widely exists in railway traction power supply system, which affects power quality and efficient utilization of electric energy. In order to achieve energy-saving of traction power supply system, the scientific utilization of regenerative braking power has become a key measure. The installation of back-to-back converter is taken as the research object to realize the energy-saving of railway traction power supply. The control strategy and economic model of back-to-back converter are established. The energy-saving benefit of installing back-to-back converter is analyzed using actual traction load and typical parameters with internal rate of return as evaluation index. The results show that the installation of back-to-back converter can achieve the considerable energy-saving benefit and has investment value.

Research on Wind Farm Power Quality Evaluation Method Based on Improved Relative Intensity Entropy Method

CHU Xinyan, ZHENG Xiang

2023, 0(6):  75-79.  doi:10.16628/j.cnki.2095-8188.2023.06.012

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A wind farm power quality evaluation method based on improved relative intensity entropy method is proposed to address the issue of weight allocation and accuracy in wind farm power quality evaluation. This corrects the unreasonable distribution of entropy weight when the traditional relative intensity entropy method approaches 1.The combination of relative intensity entropy method and analytic hierachy process (AHP) extended scaling method to calculate indicator weights improves the accuracy of weights and corrects the problem of unreasonable entropy weight allocation. The optimized combination model with the minimum total deviation value was used to evaluate the indicators and weights. The comprehensive evaluation of the power quality of wind farms was achieved. The analysis results of the example show that the proposed method is reliable and reasonable to evaluate the power quality.

Design of Universal Highly Real-Time Synchronous Acquisition Battery Management System

PAN Mingjun, WEI Yangchao, WANG Wanchun, WANG Feng, ZHANG Jie, LI Xiang

2023, 0(6):  80-85.  doi:10.16628/j.cnki.2095-8188.2023.06.013

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Aiming at the universal requirement of energy storage battery management system, a universal and real-time synchronous acquisition battery management system is proposed. The design of highly real-time synchronous acquisition scheme of the proposed system is introduced. The universal design of the system is expounded from four aspects: address adaptive design, all-channel temperature acquisition design, universal current sampling design and low power consumption operation mode design. The feasibility of the design scheme is verified by the theoretical analysis and experimental test data. The proposed battery management system can be widely applied to battery modules of different manufacturers. Through the actual operation, the complete battery cell data curves of the system are obtained and the feasibility of the system is verified.