Hunan Electric Power

Optimal Efficiency Control Method for Large-Scale Hydrogen Production System from Renewable Energy

MENG Xin, CHEN Maolin, WANG Xiongzheng, YANG Haoran

2023, 43(3): 2-8. doi:10.3969/j.issn.1008-0198.2023.03.001

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Large scale hydrogen production from renewable energy is an important technical means to achieve renewable energy consumption and suppress fluctuations. Aiming at the optimal operation of large-scale intermittent renewable energy hydrogen production system, an efficiency optimization control method of parallel hydrogen production units is proposed. Firstly, the efficiency model of hydrogen production units is established. Secondly, by constructing the efficiency optimization objective function and constraints of multiple parallel hydrogen production units, the optimal power distribution value of each parallel hydrogen production device at different input power is optimized by exhaustive optimization algorithm. Finally, the effectiveness and feasibility of the method are verified by MATLAB simulation, and its operating efficiency are compared with the power sharing and hierarchical switching modes. The results show that the efficiency optimization control method can effectively improve the operation efficiency of the parallel system under fluctuating power.

EV Charging Load Forecasting Based on Model Driven and Data Driven

LI Yijie, SONG Heng, YE Chenhui, SHEN Qingxiang

2023, 43(3): 9-15. doi:10.3969/j.issn.1008-0198.2023.03.002

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At present, research on predicting the charging load of electric vehicles has not solved the problem of not being able to obtain real-time origin destination (OD) data in practical applications and considering the actual perception and decision-making psychology of car owners. In response to this issue, based on comprehensive consideration of dynamic traffic information, environmental temperature, real-time vehicle flow, queuing theory, and other methods, this paper establishes a new in-depth learning framework for urban transportation system OD flow prediction, and completes the spatiotemporal distribution prediction of electric vehicle charging load. This paper firstly analyzes the impact of various factors such as urban traffic network information, day type, and weather on the driving rules of electric vehicles. The starting and ending points of corresponding private car and taxi driving behaviors are obtained through a bidirectional short-term memory recursive neural network algorithm. Secondly, a link impedance and node impedance model considering dynamic traffic information and intersection flow is introduced, as well as an air conditioning energy consumption model considering ambient temperature and vehicle real-time speed. The real-time Dijkstra algorithm is used to plan the minimum travel cost travel path for the starting and ending points of electric vehicles, simulating the driving behavior of electric vehicle users. Finally, path planning experiments and charging demand prediction experiments for different types of electric vehicles are completed in different application scenarios. The results show that the spatiotemporal distribution characteristics of the charging demand obtained are consistent with the objective demand.

Research on Frequency Detection Optimization Method Based on Double Input Improved Second Order Generalized Integrator

HUANG Taiyu, HAN Wei, MA Weidong, LIU Chao, DANG Yiqi

2023, 43(3): 16-20. doi:10.3969/j.issn.1008-0198.2023.03.003

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Aiming at the problem that the voltage of the distributed power grid-connected point under complex power grid is prone to disturbance, imbalance and other non-ideal working conditions, which adversely affects the accurate observation of frequency information, the working principle of the improved second-order generalized integrator is used to propose a frequency observer constructed based on the double-input improved second-order generalized integration principle, so that the system can realize accurate observation of frequency information under complex working conditions such as frequency disturbance and voltage three-phase amplitude imbalance. The simulation results show that the proposed method has a smaller overshoot of frequency observation under frequency disturbance and amplitude imbalance, and there is no oscillation of the observed value, which verifies its effectiveness and accuracy in the dynamic performance of frequency observation.

Research on Source-Grid-Load-Storage Coordinated Planning Model of Rural Integrated Energy System Considering Demand Response

LIU Ying, SONG Limin, GONG Qiang, LYU Sen, CHEN Sen, XIE Ning

2023, 43(3): 21-28. doi:10.3969/j.issn.1008-0198.2023.03.004

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In order to promote the integrated development of source, grid, load and storage of integrated energy system, promote the clean transformation of integrated energy system, and meet the requirements of“low fossil energy consumption and high energy utilization efficiency”of integrated energy system for the transformation and upgrading of the energy industry, a coordinated planning model of source, grid, load and storage of rural integrated energy system is proposed. Compared with the traditional integrated energy system planning method, the role of demand response and energy storage in improving the energy efficiency of the integrated energy system is considered, and the carbon emission cost of the system is considered to improve the carbon reduction benefit. Taking a rural integrated energy system in Zhejiang province as an example, a case study is carried out, and the simulation results are compared with the original energy consumption and carbon emissions, and it is concluded that the proposed integrated energy system source-grid-load-storage coordinated planning model has good effects in reducing system energy consumption and reducing system carbon emissions, and the proposed coordinated planning method has good practical application value.

Electric Vehicle Charging Network Planning Considering Charging Driving Distance Based on Genetic Algorithm

XIE Ying, ZHENG Zhong, LIU Jianfeng, GAO Xi, LI Daxiang

2023, 43(3): 29-36. doi:10.3969/j.issn.1008-0198.2023.03.005

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In order to shorten the charging distance of electric vehicles and improve the charging convenience of car owners, a stochastic planning model for charging electric vehicle electrical network based on flow capturing location model(FCLM) is established. Under the premise of a given number of charging stations, by optimizing the construction address of charging stations, while ensuring that the charging distance of electric vehicles meets opportunity constraints, the average charging distance of electric vehicles in the entire transportation network is minimized. The established programming model is a 0-1 integer programming problem with opportunity constraints. The genetic algorithm based on the feasibility rule is used to solve it. In order to improve the solution performance, the crossover and mutation operators in the genetic algorithm(GA)are improved. Finally, an example based on a 25 node transportation network is used to validate the effectiveness of the proposed model and solution method. The probability distribution characteristics of charging distance under different planning boundary conditions, as well as the impact of confidence and the number of charging stations built on the planning results, are analyzed.

Study on Multi-Objective Optimization Model of Gas-Electricity Interconnected Comprehensive Energy System

LI Menglu, Wuyungaowa, JIANG Peng

2023, 43(3): 37-44. doi:10.3969/j.issn.1008-0198.2023.03.006

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Aiming at the problems of energy shortage and environmental deterioration caused by the current energy supply and consumption mode dominated by fossil energy such as coal, the optimal dispatching and operation of integrated electricity-gas energy system under the principle of power to gas (P2G) technology is studied by using the development and utilization idea of integrated energy system. By constructing the multi-objective cooperative optimization operation model of P2G participating in gas-electricity interconnected comprehensive energy system, based on the functional characteristics of P2G, such as carbon capture effect and gas-electricity coupling effect, multiple targets are processed with the help of cuckoo algorithm.The calculation results show that P2G equipment has the functions of effectively reducing wind rejection rate, peak load shifting and improving carbon emission reduction benefits, which provides a new way for renewable energy consumption.

Research on Coordinated Programming Model of Electricity- Gas-Cold-Heating Integrated Energy System

GUO Junnan, ZHANG Peng, WANG Tan, XIE Tiantian, YUE Guangwei, XIE Ning

2023, 43(3): 45-52. doi:10.3969/j.issn.1008-0198.2023.03.007

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Traditional energy systems often conduct individual operational analysis and ignore the coupling relationships between different energy systems, leading to insufficient complementarity between different energy sources. Integrated energy systems have become an important technology supporting energy transition, which can integrate various energy sources in a certain area to ensure diverse demands are met while improving energy utilization efficiency. This paper first introduces the modeling of coupling devices for electricity-heat-cooling-power in integrated energy systems, and conducts power flow analysis on this basis. Furthermore, a coordinated planning model of integrated energy systems with various energy sources mutually supporting each other is constructed. Finally, the feasibility and practicality of the comprehensive energy system are verified through an example.

Study on Wind Power Prediction Based on Wake Effect and Machine Learning

YU Zhongze, LIU Zhenqing, MA Chi

2023, 43(3): 53-59. doi:10.3969/j.issn.1008-0198.2023.03.008

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In response to the problem of severely overestimating wind speed loss in the wake zone when using the Jensen wake analysis model to analyze wake effects without considering the additional turbulence intensity brought by upstream fans on downstream wind speed recovery, a Gaussian wake model is proposed to consider wake effects and combine it with machine learning algorithms to improve existing short-term wind power prediction methods based on physical effects. This theoretically improves the accuracy of short-term wind power prediction models in predicting wind speed in the wake region. Experiments are conducted using historical wind power data from real wind farms, and the results show that compared to not considering wake effects, the model's prediction performance had a mean square error reduction of about 15%,and compared with the Jensen wake analysis model, the model's prediction performance had a mean square error reduction of about 7%.

Effect of Mn Content in Steel on Hot Dip Galvanizing

SONG Zhifeng, WANG Meng, WANG Xinming, FENG Juning, HU Jingxian, LIU Yan, WU Yu

2023, 43(3): 60-63. doi:10.3969/j.issn.1008-0198.2023.03.009

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The tissue changes and growth kinetics of Fe-x%Mn alloy plating are investigated using scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) instrumentation after immersion plating of pure iron, Fe-0.3%Mn, Fe-0.8%Mn, Fe-1.3%Mn, Fe-1.8%Mn, and Fe-2.5%Mn alloys in a pure zinc bath at 450℃ for 30~480 s. The results show that with the addition of Mn content, the plating organization is basically ζ phase and δ phase, and when the Mn content is 1.8%, cracks began to appear in the plating.In the growth kinetics of Fe-x%Mn alloy plating, the thickness of the plating is reduced compared to that of pure Fe plating,the growth rate of the plating thickness is increased with the extension of the immersion plating time, and the growth mechanism of Fe-Mn alloy is mainly controlled by diffusion mechanism.During the immersion process, the diffusion channels sequentially pass through the liquid phase ζ entry phase δ,and the increase in the mass fraction of manganese in the phase layer will cause the diffusion channel to deviate from the true alloy composition.

Research on Optimal Configuration of Distributed Power GenerationBased on Particle Swarm Optimization Algorithm

YANG Jin, SONG Chun, YANG Nan

2023, 43(3): 64-69. doi:10.3969/j.issn.1008-0198.2023.03.010

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With a large number of distributed power sources and electric vehicle clusters connected to the distribution network, the types of loads are diversified. Due to the randomness and volatility of distributed generation, it brings great challenges to the planning of distribution network. Therefore, the planning method of diversified load access to adapt to distribution network is proposed. Firstly, the distribution network planning model is established with the goal of maximizing the capacity of distributed generation allowed to access the line. Then, by accessing distributed power supply at each node, a large number of alternative schemes are generated.Finally, the particle swarm optimization algorithm is used to select the optimal access scheme for the generated massive access scheme to guide the planning of the distribution network. The simulation results of practical examples verify the validity and rationality of the model.

Evaluation Method of Distribution Network Operation Level Based on Combination Weighting and Improved Grey Correlation

LAN Zheng, GUO Kaitao, YIN Rui, ZOU Bin, ZENG Jinhui, TAN Youqi, LI Juan

2023, 43(3): 70-76. doi:10.3969/j.issn.1008-0198.2023.03.011

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Reasonable evaluation of distribution network operation level can provide reference for distribution network planning, transformation and operation optimization, which is of great significance to the safe and stable operation of distribution network. By using the related indexes that affect the operation level of distribution network, a method based on combination weighting and improved grey correlation is proposed to evaluate the operation level of distribution network. Firstly, the correlation coefficient of each evaluation index of distribution network operation level is introduced, and the combined weight method is used to modify the comprehensive weight of each index, and then the comprehensive evaluation index of each region is obtained, thus, the weak area of distribution network operation level is identified and the target area in urgent need of transformation is obtained. Then, the mean difference influence coefficient is introduced to improve the traditional grey correlation method, and the correlation degree between the influencing factors of distribution network operation level and the comprehensive evaluation index is obtained, so as to get the influence degree of each influencing factor on the distribution network operation level. Finally, the effectiveness and superiority of the proposed method are verified by an example.

Research on Intelligent Auxiliary Monitoring System Based on Big Data Mining and Rule Engine

ZHOU Hui, WANG Yao, LUO Renqiang, DANG Junbang, XIAO Zhenxin, ZHAO Hang

2023, 43(3): 77-81. doi:10.3969/j.issn.1008-0198.2023.03.012

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With the purpose of improving the intelligent level of power plant monitoring, this paper introduces an intelligent auxiliary monitoring system based on big data mining and rule engine, supported by big data technology and relying on various advanced machine learning algorithms. The system establishes the early warning model of all kinds of systems and equipment in power generation enterprises, which can accurately detect abnormal status of parameters and equipment, and reduce the monitoring pressure of operators. Early warning should be carried out in the early stage of equipment failure, and fault identification and troubleshooting guidance should be given to the early warning. The test results show that the system is beneficial to realize more comprehensive monitoring of equipment status in power plant, and it can further improve the operation level of units and the health level of equipment.

Design of Power Transformer Vibration Absorber Based on Magnetorheological Grease

LU Xinsheng, XU Sheng, GE Chen, REN Jie

2023, 43(3): 82-87. doi:10.3969/j.issn.1008-0198.2023.03.013

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Noise may be generated during the operation of power transformer, and the installation of damping device is one of the effective ways to control the noise. Aiming at the disadvantage of the existing damping device of power transformer, a new type of magnetorheological grease damper is designed. Firstly, the mechanism of transformer vibration noise and the mechanical properties of magnetorheological grease are analyzed, and the feasibility of vibration reduction is demonstrated. Then the structure of the Vibration absorber is designed and the magnetic field simulation is carried out. The results show that the designed electromagnetic field can meet the regulation requirements of magnetorheological grease. The vibration absorber damping can be adjusted by changing the coil current,the adaptive fuzzy PID control algorithm is designed finally,adjust the output current according to the vibration signal collected by the acceleration sensor to obtain better vibration reduction effect.The simulation results show that the algorithm has low overshoot and good robustness. This paper provides a feasible variable damping scheme for noise control of power transformer.

Application of Improved Grey Forecasting Model in Power Load Forecasting

DU Weichun, LUO Hongbo, YANG Nan

2023, 43(3): 88-93. doi:10.3969/j.issn.1008-0198.2023.03.014

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The traditional grey prediction model has the defect of low prediction accuracy. Based on the GM (1,1) model in the grey system, this paper analyzes the limitations of the model and gives solutions to improve the accuracy of load forecasting. Aiming at the problem that there may be abnormal data in the original data, which leads to the low accuracy of the prediction results, this paper adopts the method of smoothing the original data to reduce the influence of abnormal data on the prediction results. Considering that the initial value of the traditional GM (1,1) model usually selects the data of the earliest one year in the historical data, which is not closely related to the future and has low regularity, this paper uses the data of the latest one year in the historical data as the initial value of the prediction model. The residual processing method is used to modify the original model to improve the prediction accuracy. Considering the above three improvement methods, the GM (1,1) model of the traditional system is improved. The simulation results based on a practical example in a certain area show that compared with the traditional grey prediction model, the prediction accuracy of the improved prediction model is greatly improved, which verifies the effectiveness of the improvement measures.

Research on Visual Recognition and Positioning Method of Distribution Network Grounding Ring

XIONG Xixi, WANG Xuhong, WEN Yi

2023, 43(3): 94-102. doi:10.3969/j.issn.1008-0198.2023.03.015

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In order to guarantee the accuracy of the grounding protection wire hung by the banding robot, a research on the precise identification and positioning method of the grounding ring of the distribution network is carried out. In order to improve the recognition accuracy and easy deployment on the host computer, YOLOX-S is used as the basis, the simplified BiFPN network is used instead of the PAFPN feature utilisation layer of the neck, GIoU-Loss is used as the localisation loss function and Focal Loss is adopted as the confidence prediction loss function. A binocular vision method is used to locate the detected grounding ring, the binocular camera is calibrated to obtain the internal and external parameters and distortion coefficients of the camera, stereo correction is applied to the left and right images, the semi-global stereo matching algorithm is used to obtain the image parallax, and finally the depth and coordinates of the grounding ring are obtained using the reprojection matrix, so as to achieve accurate recognition and localization of the grounding ring. The proposed identification and positioning method is applied to the experiments of hanging grounding protection wires by a power strip operation robot, and the results show that the method can achieve accurate hanging of wires by the robot and can be extended to other operations of power robots.

Survey of Transmission Line and Ground Wire Image Recognition Algorithms

LIU Daosheng, LAI Yongyao, CHEN Xingrong, LIU Hui

2023, 43(3): 103-108. doi:10.3969/j.issn.1008-0198.2023.03.016

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Based on the advantages of image recognition algorithm of improving the efficiency and reliability of transmission line inspection, this paper introduces the research status of image recognition algorithm for transmission line and ground wire, analyzes the mainstream algorithms of the three key steps of image preprocessing, transmission line and ground wire extraction and defect recognition, and briefly analyzes the shortcomings of these algorithms.And the same time, the future research directions of transmission line conductor and ground line image recognition algorithms are prospected.

Application of Automatic Voltage Control System Technology Based on Voltage Fluctuation of AC UHV Grid

ZHANG Yuanwang , LI Yuqi, ZHANG Shuo, SHI Guoyu , ZHI Xiaochen

2023, 43(3): 109-114. doi:10.3969/j.issn.1008-0198.2023.03.017

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This paper introduces the principle of voltage fluctuation of UHV power grid and the reactive power control system of UHV power grid. Taking the voltage fluctuation of UHV power grid in East China as the research object, the mainstream AVC control optimization model and the method of building simulation platform are used for analysis. It is verified by application that the strategy can effectively improve the results of AVC assessment by dispatching institutions due to voltage fluctuation of UHV power grid. In engineering application, it provides an effective reference for improving the AVC qualification rate of power plants and reducing the AVC assessment of power plants by dispatching institutions.

Research on Comparison Method of Substation Design Scheme Based on Life Cycle Cost

LIANG Jinzheng, LIANG Jiuling, XIONG Zhendong, HAO Juncong, SUN Chao, LI Xizhe

2023, 43(3): 115-119. doi:10.3969/j.issn.1008-0198.2023.03.018

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The requirements of power grid refined equipment cost accounting,lean value management and precise investment are constantly improving. Under this background, considering the cost consumption of substation equipment during the period from construction to decommissioning, each index that accurately reflects the life cycle cost is constructed, to compare the difference of each sub-index of the life cycle cost of different types of substations.

Zero Sequence Resistive Current Differential Relay Protection Method of Tie-Line for Centralized New Energy Power Station

LI Yi, JIN Jiangjiang, ZHANG Peng, LI Chunli

2023, 43(3): 120-124. doi:10.3969/j.issn.1008-0198.2023.03.019

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Based on a typical single-phase grounding fault of tie-line in a centralized new energy power station, the zero sequence current characteristics of the fault are analyzed, and a differential relay protection method of zero sequence resistive current of tie-line in a small resistance grounding power station is proposed. The power stations on both sides of the tie line are grounded by small resistance, and the zero-sequence differential resistive current component is a constant when the tie line is grounded in single phase, which has nothing to do with the capacitance of the tie line and the power stations on both sides to the ground. This method improves the accuracy and sensitivity of judging the single-phase grounding fault of power station tie line.

On-Load Tap Changer Fault Diagnosis Based on Time Domain Characteristic Parameters and Vibration Signal Analysis

YANG Tong, JIANG Xiaofeng, YANG Ruilin, CHEN Wei

2023, 43(3): 125-132. doi:10.3969/j.issn.1008-0198.2023.03.020

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Due to the frequent switching and strict operating conditions of on-load tap changers (OLTC), OLTC has become one of the most vulnerable parts of power transformers. The accurate diagnosis of OLTC fault is of great significance for ensuring the stable operation of the power system.Based on variational modal decomposition, the OLTC vibration signal is decomposed into several modal components. The time-domain characteristic parameters of the OLTC vibration signal are extracted based on the modal components, and a series of fault simulations are used to statistically analyze the time-domain characteristic parameters of the OLTC vibration signal. By establishing these time-domain characteristic parameters, an OLTC vibration signal database is established to achieve OLTC fault diagnosis.

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