Table of Content

25 April 2024, Volume 44 Issue 2

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Researches and Tests

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Risk Assessment Model for Load Redistribution Attacks Based on Game Theory

YU Mengxi, YAN Yu, ZHOU Zhanfan, DU Min, WANG Lianhong

2024, 44(2):  1-8.  doi:10.3969/j.issn.1008-0198.2024.02.001

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To assess the risk of cyber-attack,this paper constructs a bilayer assessment model of load redistribution attack risk based on game theory,introduces false data attacks and load redistribution attacks,and constructs a two-layer optimisation model for the risk of load redistribution attacks based on a game-theoretic approach.In addition,this paper uses the KKT condition to transform the bilayer model into a single-level mixed-integer linear programming model,and carries out and analyzes simulation experiments on the IEEE 14-bus system and the IEEE 30-bus system,to assess the risk of load redistribution attacks on the security and economic operation of the power system. In addition,this paper provides suggestion on how to prevent and defend against load redistribution attacks.

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Research Progress of Process Simulation of Solid Oxide Cells Based on Aspen Software

WANG Jing, WANG Yao, HU Xuelei, XU Song, LIU Tong

2024, 44(2):  9-18.  doi:10.3969/j.issn.1008-0198.2024.02.002

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The paper summarizes the method of process simulation of solid oxide cells through the existing modules and functions in Aspen software,introduces the subsequent optimization of solid oxide cell simulation,the improvement from steady state model to dynamic model and the application of the cell model in a variety of occasions, simulates the process of combining the solid oxide cell model with the gas turbine,plasma gasification, the cooling,heating and power triple-heat system and the cogeneration system.Finally the paper looks forward to the future research on the process simulation of solid oxide cells based on the Aspen software.

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Review of Reactive Voltage Optimal Control Research in Power Grid With High Proportion Access of New Energy

ZHANG Ruiqi, FU Letian, LI Mengjiao, CHU Xu, YU Shaoshuai

2024, 44(2):  19-28.  doi:10.3969/j.issn.1008-0198.2024.02.003

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For the application of reactive voltage optimization and control techniques,the reactive voltage optimization modeling methods of power grid in the environment of high proportion of new energy access are summarized,which are mainly divided into multi-time scale reactive voltage optimization,hierarchical and partition voltage optimization,active and reactive voltage coordination optimization,and reactive voltage optimization based on model predictive control.The mathematical methods of reactive voltage optimization are briefly analyzed,which are mainly divided into random variable processing method and reactive voltage optimization model solving method.Combined with the structural changes of“source-grid-load-storage”,the development trend of energy internet and the current situation of power market reform,the future research is prospected from the perspective of multi-dimensional“source-grid-load-storage”coordinated voltage control,multi-heterogeneous energy collaborative optimization control,and“source-grid-load-storage”collaborative optimization under the market environment.

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Study on the High Temperature Steam Corrosion of AlCrNbSiTi High Entropy Alloy Coatings

LIU Jie, LI Zhenggang, YANG Bing

2024, 44(2):  29-34.  doi:10.3969/j.issn.1008-0198.2024.02.004

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Magnetron sputtering is used to prepare AlCrNbSiTi high entropy alloy coatings with different bias pressures,and the effect of bias pressure on the structure and properties of AlCrNbSiTi coatings is investigated by analyzing the morphologies,chemical compositions,hardnesses and morphologies of the coatings with different bias pressures after being corroded by water vapour.The results show that the bias voltage can regulate the surface roughness of the coatings significantly,and the surface roughness of the sample with a bias voltage of 150 V is only 3.35 nm.The sample with a bias voltage of 50 V exhibits the maximum hardness and elastic modulus of 18.19 GPa and 232.4 GPa,respectively.The failure mechanism of the coatings by water vapour corrosion is pitting corrosion,and the coating has the best corrosion resistance with a bias voltage of 50 V.

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Method of Current Disturbance Observation Control for LCL-Type Grid Connected Inverters With Additional Virtual Impedance

ZHU Hongping, GUO Liwen, QIAN Wanming, ZHU Hongzhi, HAN Yinglong

2024, 44(2):  35-43.  doi:10.3969/j.issn.1008-0198.2024.02.005

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Aiming at the fact that the output current quality of actual LCL-type grid connected inverters is easily affected by grid voltage background harmonics and grid impedance under weak current grid conditions,this paper proposes a current disturbance observation and control method for LCL-type grid connected inverters with additional virtual impedance.Firstly,this paper introduces a disturbance observer on the basis of conventional double closed-loop control,treating the background harmonic of the grid voltage as an external disturbance of the system.The disturbance observer is used to estimate the disturbance momentum in real time and dynamically eliminate the influence of disturbance on the system through feedforward compensation.Secondly, impedance analysis method is used to analyze the robustness problem caused by grid impedance in weak current grid systems.Based on the current disturbance observation control method,virtual impedance is added for optimization design,so that the phase margin of the grid connected inverter system is still greater than the stability margin constrained by the system when the impedance intersection frequency changes within a large range.The simulation comparison results show,the proposed method improves the robustness of the system to grid impedance while maintaining good current quality.

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Experimental Study on Fire Extinguishing by Water Spray System With Water-Based Extinguishing Agent for UHV Converter Transformer

CHEN Baohui, WU Chuanping, ZHOU Tiannian, LIU Yu, LI Bo

2024, 44(2):  44-49.  doi:10.3969/j.issn.1008-0198.2024.02.006

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Using 1∶1 full-scale ultra-high voltage (UHV) converter transformer fire model,a water spray fire extinguishing system adding water extinguishing agent is developed to extinguish full-scale UHV transformer fire. A fire protection renovation scheme for the converter station which had installed the water spray fire extinguishing system and the solution to improve the fire resistance and knock resistance of the water spray fire-fighting system is proposed,which improves the extinguishing ability of UHV converter transformer.The test results show that under the standard of National Fire Protection Association for water spray fixed systems for fire,the water spray fire extinguishing system adding 6% extinguishing agent extinguishes the full-scale fire of UHV converter transformer in only 34 s,which verifies the fire extinguishing ability of the water spray fire extinguishing system adding water extinguishing agent.

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Analysis of Conducted Interference and Research of its Suppression Measures for VFTO on Electronic Voltage Transformer

LI Chuang, LIAO Xingrui, YU Quanquan, XIAO Yunteng

2024, 44(2):  50-59.  doi:10.3969/j.issn.1008-0198.2024.02.007

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In this paper,the equivalent circuit of the capacitive divider transformer sensing unit is established by taking the air insulated substations(AIS) disconnector operation as the interference source object,the influence of the parameters of the capacitive divider transformer sensing unit on the frequency characteristics of the voltage division ratio is analyzed,and the output voltage of the transformer sensing unit under very fast transient overvoltage (VFTO) conduction interference is studied by combining the disconnector disintegration capacitive small current simulation circuit.Trough the simulation the suppression effect of the arrester,the wave blocker,the dual RC filter and transient voltage suppressor(TVS)tube combination protection circuit is analyzed.The results show that the suppression effect of the arrester on the VFTO generated by AIS disconnector operation is not ideal,and even the peak value will increase.The wave blocker can effectively suppress the high-frequency component in the VFTO.The dual RC filter and TVS tube combination protection circuit not only limits the output voltage of the sensing unit to the allowable range,but also filters out the high-frequency components in it.

New technology and Application

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Hierarchical Cooperative Control Study of Multi-Storage Converters

WANG Can, DENG Wenhua, ZHANG Kan, CHEN Gang, XIA Xiangyang, SONG Hongtao

2024, 44(2):  60-67.  doi:10.3969/j.issn.1008-0198.2024.02.008

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The output voltage and frequency of energy storage inverters in microgrids are unstable and the active and reactive power are unbalanced under islanded operation.The traditional droop control of inverters cannot adjust the voltage and frequency of microgrid islanded operation without static error,and can not meet the active and reactive power balance of microgrid islanded operation. Based on this,a hierarchical collaborative control method for multiple energy storage inverters is proposed.Based on the comprehensive consideration of the operational control objectives of energy storage inverters and the information exchange between adjacent energy storage inverters in microgrids,a hierarchical interconnected distributed collaborative control structure for microgrids is designed,and the distributed control method for multiple systems is improved.The simulation experiments results on multiple energy storage inverters in microgrids show that,the proposed control strategies have the effectiveness and collaborative control ability.

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Design of Ancillary Damping Controller of Grid-Forming VSC-HVDC Systems

WANG Canlin, ZHANG De, ZHU Sirui, LI Yong, WANG Weiyu, WEN Ding

2024, 44(2):  68-76.  doi:10.3969/j.issn.1008-0198.2024.02.009

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Voltage source converter based high voltage direct current system can provide inertia support to the receiving-end power systems. However,it also inherits the oscillatory characteristics of synchronous generator,which makes the system dynamics more complex.This paper establishes the state-space model and transfer function models of a grid-forming VSC-HVDC system connected with a receiving-end power system,which are utilized to reveal the system oscillatory characteristics under the disturbance.Ancillary damping controllers are designed to improve the damping performance of the grid-forming VSC-HVDC systems,which only requires the state variables of the grid-forming VSC-HVDC systems.The test system is built in DIgSILENT/PowerFactory to verify the performance of the proposed control strategy.The results show that the proposed control strategy can effectively dampen the dc voltage oscillation and the electromechanical oscillations in AC grids.

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Corrosion Rate Prediction of Substation Grounding Network Based on Chimpanzee Algorithm Optimized Support Vector Machine

LI Yuhan, LIU Yanyan, LIU Chuang, LIU Hai, XU Da

2024, 44(2):  77-83.  doi:10.3969/j.issn.1008-0198.2024.02.010

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In order to improve the accuracy of predicting the corrosion rate of substation grounding grids,a method based on chimpanzee algorithm optimized support vector machine for predicting the corrosion rate of substation grounding grids is proposed.Firstly,a kernel principal component analysis is conducted on the characteristic variables of the corrosion rate of the substation grounding grid to determine the significant correlation between soil resistivity,mass fraction, moisture content,and redox potential with corrosion rate.The above four characteristic variables are selected as input for the grounding grid corrosion rate prediction model. Then,the chimpanzee algorithm is used to optimize the parameters of the chimpanzee algorithm,and a corrosion rate prediction model for the substation grounding grid is established.Finally,corrosion test data is used for numerical analysis,and the prediction results are compared with those of other methods.The results show that the average relative error of the proposed model′s prediction results is 2.984%,and the root mean square error is 0.008 89 mm/a.Compared with other methods,the error fluctuation is smaller and the prediction accuracy is higher,which verifies the practicality and superiority of the proposed method for predicting the corrosion rate of substation grounding grids.

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Double Closed Loop Control Strategy With AC Bus Voltage and Reactive Power and Coordinated Control With Bus Capacitance for Synchronous Condenser

XIAO Pei, ZHU Tianyi, LIU Yanan, LIU Haoran, LIU Yuan

2024, 44(2):  84-89.  doi:10.3969/j.issn.1008-0198.2024.02.011

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Aiming at the technical problems of power overshoot and AC bus voltage fluctuation in the process of reactive power compensation of high voltage converter station,by considering the influence of reactive power disturbance,an advanced control method of double closed loop condenser with AC bus voltage outer loop and reactive power of synchronous condenser inner loop is designed.The control method can effectively suppress the reactive power overshoot while ensuring the rapid response of the condenser to the AC bus voltage fluctuation.In order to further suppress the large fluctuation of AC bus voltage caused by reactive power fluctuation in high-voltage converter station,a coordinated control strategy of condenser and AC bus capacitor reactive power compensation is designed and implemented by means of capacitor series connection to absorb resistance,which improves the steady-state and dynamic performance of high-voltage converter station.The correctness and effectiveness of the proposed control method are verified by PSCAD software.

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Design and Implementation of Flexible Electricity Trading Data Generation Components

WEI Yuping, ZHENG Qiongxuan, WU Yihan, SUN Jieyi, ZHANG Bingjin, LYU Dangzhen

2024, 44(2):  90-96.  doi:10.3969/j.issn.1008-0198.2024.02.012

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To resolve the complex and variable challenges arising from the diverse applications and trading data generation processes in the construction of the electricity spot market,the paper proposes a design approach for a flexible electricity trading data generation component.Through business modeling and data feature analysis of various types of trading data,with the aim of “reuse and adaptability to change”,the paper abstracts the trading data generation process and separates the common logic and personalize the flexible adaptation of the business aspects of trading data generation.Using a microservices architecture,this design is integrable into application systems in a plug-and-play manner in component form and meets the data requirements of integrity,reliability,flexibility,and efficiency for various applications in the construction of the electricity spot market.This component has been successfully applied in various application systems for supporting the business of spot market operations in dispatching agencies dealing with massive trading data,demonstrating its flexibility and effectiveness in practical operation.

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New Type of Environmentally Friendly Three-Phase Common Enclosure Basin Insulator for GIS Busbar

ZHAO Junqing, GAO Yang, WU Wenhai, DAI Tongling, CHEN Yu, LIU Dongyang

2024, 44(2):  97-103.  doi:10.3969/j.issn.1008-0198.2024.02.013

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This article provides a detailed introduction to the design features of the new 126 kV three-phase common enclosure basin insulator and uses finite element analysis software to perform detailed calculations and analysis of its insulation and mechanical performance.The research results show that by increasing the grounded shielding ring,the electric field intensity in the three-phase junction area can be effectively reduced.The design structure of the basin insulator with a circular convex platform can withstand high gas pressure values.During the casting process,applying a special material surfactant agent on the surface of the central component can effectively improve the bonding strength of the component.The insulator passed successfully a complete set of type tests,further confirming its high insulation performance and mechanical reliability.

Experience and Discussion

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SOC Balancing Strategy for Distributed Energy Storage System Based on Improved Resistive Droop Control

YAN Shi, TAN Haiyang, XIAO Hua, CHEN Ci, LI Shengqing

2024, 44(2):  104-111.  doi:10.3969/j.issn.1008-0198.2024.02.014

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During the operation of low voltage microgrid,due to the inconsistency of the initial state of distributed energy storage units and the impedance difference of the output line,unbalanced state of charge (SOC) is easy to occur when the traditional resistive droop control is adopted.Therefore, the SOC balancing strategy for energy storage system based on improved resistive droop control is proposed in this paper.Firstly,the dynamic virtual complex impedance is introduced to eliminate the impedance difference of the output line of each inverter,and the power decoupling of the resistive droop control is realized and the active power is precisely equalized.Then,the traditional resistance droop control equation is improved,and the droop coefficient is adjusted adaptively by SOC changes of each distributed energy storage units to ensure SOC balance of each energy storage unit in the low-voltage microgrid during the charge and discharge process,and the voltage and frequency deviation in the droop control process is compensated to further improve the stability of the system.Finally,a simulation model is built to verify the effectiveness of the proposed strategy.

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Coordinated Control Strategy of Reactive Power of Grid-Forming Inverter and SVG Parallel System

CHEN Yandong, PEI Xinxin, FU Youze, LI Xuyang, ZHANG Mingyu, ZHOU Kehui, TANG Haiguo

2024, 44(2):  112-121.  doi:10.3969/j.issn.1008-0198.2024.02.015

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Taking the static var generator (SVG) as an example,this paper proposes a coordinated reactive power control strategy for grid-forming inverter and SVG parallel systems to address the voltage stability issue. Summarize the operation status of the parallel system into four working conditions,and coordinate the reactive power of the grid-forming inverter and SVG injection common coupling point under different working conditions through working condition identification, reactive power compensation calculation,reactive power allocation strategy,and working condition switching,so that the parallel system can work stably and reliably in all situations.A model is built in MATLAB and simulation is conducted.The results show that the proposed control strategy can achieve fast identification and switching of operating conditions,calculation of reactive power compensation,allocation of reactive power,and fast support for common coupling point voltage.

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Research on Seamless Switching Control Strategy of Grid Connected and Off for Photovoltaic DC Microgrids

TANG Lixing, LUO Zhaoxu, WENG Yongxing, ZHANG Bo

2024, 44(2):  122-128.  doi:10.3969/j.issn.1008-0198.2024.02.016

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When the photovoltaic DC microgrid switches from grid connected mode to island mode,the sudden switching of working mode in traditional control strategies often leads to excessive or even unstable voltage fluctuations in the DC bus,endangering the stable operation of the microgrid.To address this issue,a seamless switching control strategy of grid connected and off for photovoltaic DC microgrids is proposed,which enables each photovoltaic distributed power source to track the maximum power point output during grid connection operation,support the regulation of bus voltage during island operation,and achieve power sharing of each photovoltaic power source output.The prominent advantage of this control strategy is that the control strategy of grid connected and off is unified without the need for mode switching,and it is decentralized control without the need for communication between various photovoltaic power sources with high reliability.Finally,a simulation model is built based on the MATLAB/Simulink platform,and the simulation results verify the correctness and effectiveness of the proposed control strategy.

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Experimental Study on Energy-Absorbing Anti-Icing Coating for Wind Turbine Blades

PAN Bichen, CHEN Baohui, TANG Zhuang

2024, 44(2):  129-133.  doi:10.3969/j.issn.1008-0198.2024.02.017

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Aiming at the problem that wind turbine blade are prone to icing in winter,a new kind of wind turbine blade anti-icing coating with energy absorption function is developed.The coating of blade anti-icing can absorb a certain wavelength of light and turn it into heat to raise the temperature of the paint surface,which melts the interface between the paint and the ice and let the ice fall off the wind turbine blade.The energy-absorbing pigment is prepared by chemical reaction,and mixed with film forming matrix,wear-resistant filler and other materials to produce energy-absorbing coating.By comparing the icing condition of the anti-icing blade with the ordinary blade,it is found that the coating could reduce the icing rate of the blade by 12.8% and shorten the icing time by 50%.In addition,the wear resistance test shows that the wear resistance of the coating is 2.81 L/μm,which is better than that of the original coating on the blade (1.95 L/μm).The above results show that the coating could reduce the ice coating rate and shorten the ice coating time of the blade,and had better wear resistance and longer service life.

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Research on Carbon Emission Combination Forecasting Method Based on Power Data

WEN Bo, LI Jiaxi, WEN Ming, ZHANG Xinyang, XU Jiazhu

2024, 44(2):  134-140.  doi:10.3969/j.issn.1008-0198.2024.02.018

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Aiming at the problems of low accuracy,poor stability, and difficulty in obtaining data in existing carbon emission forecasting methods,this paper proposes a carbon emission combination forecasting method based on power data.The improved BP neural network, random forest regression and Elman neural network forecasting models are established respectively, and the three models are combined and optimized to establish a carbon emission combination forecasting model based on power data. Through the simulation of power-carbon forecasting in Hunan Province,the power input variables are selected reasonably,and the combination forecasting model proposed in this paper is compared and analyzed with single forecasting and other combination forecasting models.The research result shows that power data can be effectively applied to carbon emission forecasting.Compared with the individual forecasting models and the other two combination forecasting models,the combination forecasting model proposed in this paper has higher accuracy and helps predict and reduce carbon emissions.

Faults and Analysis

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Design of Lightning Arrester Fault Detection and Automatic Switch System for Power Supply System

GUAN Ye, LIU Baiyang, MA Suipeng, FENG Xiaoming, LIU Xiaoxin

2024, 44(2):  141-147.  doi:10.3969/j.issn.1008-0198.2024.02.019

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In order to solve the problem that arrester is easily damaged and difficult to be operated and maintained by workers,a new fault detection and automatic switching method of arrester in power supply system is proposed for the first time.The method uses the fast Fourier transform to detect the current in real time,and the microcontroller to analyze the data and send out the control signal to realize the online detection of arrester fault.Through the design of automatic switching arrester mechanical structure,the spare arrester can be automatically switched one by one.The prototype of the system is developed and the test analysis is carried out.The test results show that the function of the system is feasible and effective,and it can realize the fault detection and automatic switching of arrester.

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Analysis and Improvement of Refusal-to-Move Fault in Three-Position GIS Disconnector

LIU Yufei, LIU Guofeng, YANG Rihui, HUANG Zhicong, LIU Jiawei, CHEN Jiahao, LUO Rui

2024, 44(2):  148-154.  doi:10.3969/j.issn.1008-0198.2024.02.020

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Based on the operating principle of the operating mechanism,secondary circuit design,and the experience of field operation and maintenance,the failure of the three-station GIS isolation switch is analyzed and investigated,and an improved scheme is proposed to replace the original travel switch with contactor node to realize the locking function and replace the slow motor to facilitate the braking.Through the comparison of motor current curve and cycle operation,the effectiveness of the scheme is verified, and the hidden danger of the device′s rejection is eliminated.