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Integrated Frequency-constrained Scheduling Considering Coordination of Frequency Regulation Capabilities from Multi-source Converters

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 261-274页

作者： Jiaming Li Ying Qiao Zongxiang Lu Wei Ma Xin Cao Rongfu Sun the Department of electrical Engineering Tsinghua UniversityBeijing 100084China the China Suntien Green Energy limited company Shijiazhuang 050011China the State Grid Jibei electric Power company Beijing 100054China

As the proportion of renewable energy(RE)increases,the inertia and the primary frequency regulation(FR)capability of the power system decrease.Thus,ensuring frequency security in the scheduling model has become a new technical requirement in power systems with a high share of RE.Due to a shortage of conventional synchronous generators,the frequency support of multi-source converters has become an indispensable part of the system frequency resources,especially variable-speed wind turbine generation(WTG)and battery energy storage(BES).Quantitative expression of the FR capability of multi-source converters is necessary to construct frequency-constrained scheduling model.However,the frequency support performance of these converter-interfaced devices is related to their working states,operation modes,and parameters,and the complex coupling of these factors has not been fully exploited in existing models.In this study,we propose an integrated frequency-constrained scheduling model considering the coordination of FR capabilities from multi-source converters.Switchable FR control strategies and variable FR parameters for WTG with or without reserved power are modeled,and multi-target allocation of BES capacity between tracking dispatch instruction and emergency FR is analyzed.Then,the variable FR capabilities of WTG and BES are embedded into the integrated frequency-constrained scheduling model.The nonlinear constraints for frequency security are precisely linearized through an improved iteration-based strategy.The effectiveness of the proposed model is verified in a modified IEEE 24-bus standard system.The results suggest that the coordinated participation of BES and WTG in FR can effectively reduce the cost of the scheduling model while meeting frequency security constraints.

关键词： Battery energy storage(BES) wind turbine generation(WTG) frequency regulation(FR) frequency security power system scheduling

Harmonic State Space Based Impedance Modeling and Virtual Impedance Based Stability Enhancement Control for LCC-HVDC Systems

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 287-298页

作者： Yifeng Liu Xiaoping Zhou Quan Chen Hanhang Yin Lerong Hong Hao Tian Ying Chen Siyuan Li the College of electrical and Information Engineering Hunan UniversityChangsha 410082China the Zhejiang Magtron Intelligent Technology limited Cooperation Jiaxing 314000China the State Grid Qianjiang electric Power company Qianjiang 433100China

Line commutated converter based high-voltage direct-current(LCC-HVDC)transmissions are prone to harmonic oscillation under weak grids.Impedance modeling is an effective method for assessing interaction stability.Firstly,this paper proposes an improved calculation method for the DC voltage and AC currents of commutation stations to address the complex linearization of the commutation process and constructs an overall harmonic state-space(HSS)model of an LCC-HVDC.Based on the HSS model,the closed-loop AC impedances on the LCC-HVDC sending and receiving ends are then derived and verified.The impedance characteristics of the LCC-HVDC are then analyzed to provide a physical explanation for the harmonic oscillation of the system.The effects of the grid strength and control parameters on system stability are also analyzed.To improve the impedance characteristics and operating stability of the LCC-HVDC system,a virtual impedance based stability enhancement control is proposed,and a parameter design method is considered to ensure satisfactory phase margins at both the sending and receiving ends.Finally,simulation results are presented to verify the validity of the impedance model and virtual impedance based stability enhancement control.

关键词： Line commutated converter based high-voltage direct-current(LCC-HVDC)transmission harmonic state space stability analysis harmonic oscillation virtual impedance

Modification of streamer-to-leader transition model based on radial thermal expansion in the sphere-plane gap discharge at high altitude

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Plasma Science and Technology 2024年第1期26卷 42-49页

作者：耿江海林果王平丁玉剑丁杨俞华 Department of electric Power Engineering North China Electric Power UniversityBaoding 071003People’s Republic of China China electric Power Research Institute Beijing 100192People’s Republic of China Xinjiang electric Power company Research Institute Urumchi 830000People’s Republic of China Shanxi electric Power company Research Institute Taiyuan 030001People’s Republic of China

Historically,streamer-to-leader transition studies mainly focused on the rod-plane gap and low altitude analysis,with limited attention paid to the sphere-plane gap at high altitude analysis.In this work,sphere-plane gap discharge tests were carried out under the gap distance of 5 m at the Qinghai Ultra High Voltage(UHV)test base at an altitude of 2200 m.The experiments measured the physical parameters such as the discharge current,electric field intensity and instantaneous optical power.The duration of the dark period and the critical charge of streamer-toleader transition were obtained at high altitude.Based on radial thermal expansion of the streamer stem,we established a modified streamer-to-leader transition model of the sphere-plane gap discharge at high altitude,and calculated the stem temperature,stem radii and the duration of streamer-to-leader transition.Compared with the measured duration of sphere-plane electrode discharge at an altitude of 2200 m,the error rate of the modified model was 0.94%,while the classical model was 6.97%,demonstrating the effectiveness of the modified model.From the comparisons and analysis,several suggestions are proposed to improve the numerical model for further quantitative investigations of the leader inception.

关键词： streamer-to-leader transition model high altitude streamer stem convective diffusion radial thermal expansion

Minimizing interfacial energy losses in inverted perovskite solar cells by a dipolar stereochemical 2D perovskite interface

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Journal of Energy Chemistry 2024年第3期90卷 496-503,I0011页

作者： Junjie Qian Jingjing He Qihang Zhang Chenyue Zhu Shilin Chen Zhanpeng Wei Xuesong Leng Ziren Zhou Benben Shen Yu Peng Qiang Niu Shuang Yang Yu Hou Key Laboratory for Ultrafine Materials of Ministry of Education Shanghai Engineering Research Center of Hierarchical NanomaterialsSchool of Materials Science and EngineeringEast China University of Science and TechnologyShanghai 200237China National Enterprise Technology Center Inner Mongolia Erdos Electric Power and Metallurgy Group Company LimitedOrdos 016064Inner MongoliaChina

Inverted perovskite solar cells(PSCs) have attracted broad research and industrial interest owing to their suppressed hysteresis,cost-effectiveness,and easy-fabrication.However,the issue of non-radiative recombination losses at the n-type interface between the perovskite and fullerene has impeded further improvement of photovoltaic performance.Here,we modify the n-type interface of FAPbI_(3) perovskite films by constructing a stereochemical two-dimensional(2D) perovskite interlayer,in which the organic cations comprise both pyridine and ammonium groups.The pyridine N donor can create stable bonding with the surface-uncoordinated Pb on the perovskite,thereby passivating the shallow-level defects and enhancing the air stability of the film.Furthermore,the pyridine N donor also offers a positive polar interface to decrease the surface work function of the perovskite film,enabling n-type modification.Ultimately,we employ a p-i-n photovoltaic(PV) device with the positive dipole interlayer at perovskite/fullerene contact and achieve remarkable photoelectric conversion efficiency(PCE) of 22.0%.

关键词： Perovskite solar cells Dipole interlayer Stereochemistry Non-radiative recombination

Migratable Power System Transient Stability AssessmentMethod Based on Improved XGBoost

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Energy Engineering 2024年第7期121卷 1847-1863页

作者： Ying Qu Jinhao Wang Xueting Cheng Jie Hao Weiru Wang Zhewen Niu Yuxiang Wu electric Power Science Research Institute State Grid Shanxi Electric Power CompanyTaiyuan030000China Department of electrical and Power Engineering Taiyuan University of TechnologyTaiyuan030024China

The data-driven transient stability assessment(TSA)of power systems can predict online real-time prediction by learning the temporal features before and after faults.However,the accuracy of the assessment is limited by the quality of the data and has weak transferability.Based on this,this paper proposes a method for TSA of power systems based on an improved extreme gradient boosting(XGBoost)model.Firstly,the gradient detection method is employed to remove noise interference while maintaining the original time series trend.On this basis,a focal loss function is introduced to guide the training of theXGBoostmodel,enhancing the deep exploration of minority class samples to improve the accuracy of the model evaluation.Furthermore,to improve the generalization ability of the evaluation model,a transfer learning method based on model parameters and sample augmentation is proposed.The simulation analysis on the IEEE 39-bus system demonstrates that the proposed method,compared to the traditional machine learning-based transient stability assessment approach,achieves an average improvement of 2.16%in evaluation accuracy.Specifically,under scenarios involving changes in topology structure and operating conditions,the accuracy is enhanced by 3.65%and 3.11%,respectively.Moreover,the model updating efficiency is enhanced by 14–15 times,indicating the model’s transferable and adaptive capabilities across multiple scenarios.

关键词： Transient stability assessment data-driven segmented focusing approximation portability

E2E-MFERC:AMulti-Face Expression Recognition Model for Group Emotion Assessment

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Computers, Materials & Continua 2024年第4期79卷 1105-1135页

作者： Lin Wang Juan Zhao Hu Song Xiaolong Xu Jiangsu Key Laboratory of Big Data Security&Intelligent Processing Nanjing University of Posts and TelecommunicationsNanjing210042China School of Network Security Jinling Institute of TechnologyNanjing211169China State Grid Jiangsu electric Power company limited Nanjing210000China School of Computer Science Nanjing University of Posts and TelecommunicationsNanjing210042China

In smart classrooms, conducting multi-face expression recognition based on existing hardware devices to assessstudents’ group emotions can provide educators with more comprehensive and intuitive classroom effect analysis,thereby continuouslypromotingthe improvementof teaching quality.However,most existingmulti-face expressionrecognition methods adopt a multi-stage approach, with an overall complex process, poor real-time performance,and insufficient generalization ability. In addition, the existing facial expression datasets are mostly single faceimages, which are of low quality and lack specificity, also restricting the development of this research. This paperaims to propose an end-to-end high-performance multi-face expression recognition algorithm model suitable forsmart classrooms, construct a high-quality multi-face expression dataset to support algorithm research, and applythe model to group emotion assessment to expand its application value. To this end, we propose an end-to-endmulti-face expression recognition algorithm model for smart classrooms (E2E-MFERC). In order to provide highqualityand highly targeted data support for model research, we constructed a multi-face expression dataset inreal classrooms (MFED), containing 2,385 images and a total of 18,712 expression labels, collected from smartclassrooms. In constructing E2E-MFERC, by introducing Re-parameterization visual geometry group (RepVGG)block and symmetric positive definite convolution (SPD-Conv) modules to enhance representational capability;combined with the cross stage partial network fusion module optimized by attention mechanism (C2f_Attention),it strengthens the ability to extract key information;adopts asymptotic feature pyramid network (AFPN) featurefusion tailored to classroomscenes and optimizes the head prediction output size;achieves high-performance endto-end multi-face expression detection. Finally, we apply the model to smart classroom group emotion assessmentand provide design references for classroom effect analysis evaluation

关键词： Multi-face expression recognition smart classroom end-to-end detection group emotion assessment

Optimal Scheduling Strategy of Source-Load-Storage Based onWind Power Absorption Benefit

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Energy Engineering 2024年第7期121卷 1823-1846页

作者： Jie Ma Pengcheng Yue Haozheng Yu Yuqing Zhang Youwen Zhang Cuiping Li Junhui Li Wenwen Qin Yong Guo State Grid Henan Economic Research Institute Zhengzhou450000China Zaozhuang Power Supply company State Grid Shandong Electric Power CompanyZaozhuang277000China Key Laboratory of Modern Power SystemSimulation and Control&Renewable Energy Technology Ministry of EducationNortheast Electric Power UniversityJilin132012China

In recent years,the proportion of installed wind power in the three north regions where wind power bases are concentrated is increasing,but the peak regulation capacity of the power grid in the three north regions of China is limited,resulting in insufficient local wind power consumption capacity.Therefore,this paper proposes a two-layer optimal scheduling strategy based on wind power consumption benefits to improve the power grid’s wind power consumption capacity.The objective of the uppermodel is tominimize the peak-valley difference of the systemload,which ismainly to optimize the system load by using the demand response resources,and to reduce the peak-valley difference of the system load to improve the peak load regulation capacity of the grid.The lower scheduling model is aimed at maximizing the system operation benefit,and the scheduling model is selected based on the rolling schedulingmethod.The load-side schedulingmodel needs to reallocate the absorbed wind power according to the response speed,absorption benefit,and curtailment penalty cost of the two DR dispatching resources.Finally,the measured data of a power grid are simulated by MATLAB,and the results show that:the proposed strategy can improve the power grid’s wind power consumption capacity and get a large wind power consumption benefit.

关键词： Wind power consumption two-layer optimal demand response rolling scheduling wind curtailment penalty

Reliability Analysis of a Switched Reluctance Starter/Generator

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Protection and Control of Modern Power Systems 2024年第1期9卷 112-121页

作者： Hao Chen Fan Yang Lijun Xu Qiwei Lu Xiqiang Chang Xing Wang Lijiang Dong Yi Wen Jiang Chen Gang Miao Jianmin Hu Guanjun Wang Wei Li Xiaohua Bao School of electrical Engineering China University of Mining and TechnologyXuzhou 221116China Xinjiang Institute of Engineering Urumqi 830000China International Joint Research Center of Central and Eastern European Countries on New Energy electric Vehicle Technology and Equipment Xuzhou 221008China International Cooperation Joint Laboratory of New Energy Power Generation and electric Vehicles of Jiangsu Province Colleges and Universities Xuzhou 221008China School of Information and electrical Engineering China University of Mining and TechnologyXuzhouChina China University of Mining and Technology(Beijing) BeijingChina State Grid Xingjiang electric Power Co. Ltd.UrumqiXinjiangChina China University of Mining and Technology XuzhouChina State Grid Xinjiang company limited electric Power Research Institute UrumqiXinjiangChina Xinjiang Fukang Pumped Storage Power company limited UrumqiXinjiangChina State Grid Urumqi electric Power Supply company UrumqiXinjiangChina Wuxi Inspection and Testing Certification Research Institute WuxiJiangsuChina Anhui Wannan electric Machine Co. Ltd.WannanAnhuiChina Hefei University of Technology in electrical and Automation Engineering

In this paper,the combined k-out-of-n:G model and reliability block diagram model is used to analyze the reliability of a switched reluctance starter/generator system.First,the different operational modes of a switched reluctance motor starter/generator are analyzed,and the fault states of the system are briefly described.Then the fault criteria of the system in different operational states are put forward.Secondly,a relia-bility block diagram model is established to calculate the system-level reliability,and the k-out-of-n:G model is adopted to analyze the reliability of each part of the switched reluctance starter/generator system.To verify effectiveness,the first-order Markov model is also used to analyze the reliability of each part of the switched reluc-tance starter/generator system.Considering the compu-tational complexity and accuracy of the system,the k-out-of-n:G model is more suitable for system component level reliability analysis.Finally,a 6/4 switched reluctance motor is used as the simulated and experimental platform motor.The final results verify the effectiveness of the reliability analysis model.

关键词： system switched generator

Design of a Multifrequency Signal Parameter Estimation Method for the Distribution Network Based on HIpST

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Energy Engineering 2024年第3期121卷 729-746页

作者： Bin Liu Shuai Liang Renjie Ding Shuguang Li Tongliao Power Supply company State Grid East Inner Mongolia Electric Power Co.Ltd.Tongliao028000China School of electrical Engineering Northeast Electric Power UniversityJilin132012China

The application of traditional synchronous measurement methods is limited by frequent fluctuations of electrical signals and complex frequency components in distribution networks.Therefore,it is critical to find solutions to the issues of multifrequency parameter estimation and synchronous measurement estimation accuracy in the complex environment of distribution networks.By utilizing the multifrequency sensing capabilities of discrete Fourier transform signals and Taylor series for dynamic signal processing,a multifrequency signal estimation approach based on HT-IpDFT-STWLS(HIpST)for distribution networks is provided.First,by introducing the Hilbert transform(HT),the influence of noise on the estimation algorithm is reduced.Second,signal frequency components are obtained on the basis of the calculated signal envelope spectrum,and the interpolated discrete Fourier transform(IpDFT)frequency coarse estimation results are used as the initial values of symmetric Taylor weighted least squares(STWLS)to achieve high-precision parameter estimation under the dynamic changes of the signal,and the method increases the number of discrete Fourier.Third,the accuracy of this proposed method is verified by simulation analysis.Data show that this proposed method can accurately achieve the parameter estimation of multifrequency signals in distribution networks.This approach provides a solution for the application of phasor measurement units in distribution networks.

关键词： Discrete fourier transform taylor series hilbert transform multifrequency signal parameter estimation