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Research on high energy efficiency and low bit-width floating-point type data for abnormal object detection of transmission lines

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Global Energy Interconnection 2024年第3期7卷 324-335页

作者： Chen Wang Guozheng Peng Rui Song Jun Zhang Li Yan China electric power Research Institute Beijing 100192P.R.China Information&Telecommunications company State Grid Shandong Electric Power CompanyJinan 250001P.R.China

Achieving a balance between accuracy and efficiency in target detection applications is an important research topic.To detect abnormal targets on power transmission lines at the power edge,this paper proposes an effective method for reducing the data bit width of the network for floating-point quantization.By performing exponent prealignment and mantissa shifting operations,this method avoids the frequent alignment operations of standard floating-point data,thereby further reducing the exponent and mantissa bit width input into the training process.This enables training low-data-bit width models with low hardware-resource consumption while maintaining accuracy.Experimental tests were conducted on a dataset of real-world images of abnormal targets on transmission lines.The results indicate that while maintaining accuracy at a basic level,the proposed method can significantly reduce the data bit width compared with single-precision data.This suggests that the proposed method has a marked ability to enhance the real-time detection of abnormal targets in transmission circuits.Furthermore,a qualitative analysis indicated that the proposed quantization method is particularly suitable for hardware architectures that integrate storage and computation and exhibit good transferability.

关键词： power edge Data format Quantification Compute-in-memory

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

Unconventional photon blockade in the two-photon Jaynes–Cummings model with two-frequency cavity drivings and atom driving

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Chinese Physics B 2024年第2期33卷 164-168页

作者：刘欣田梦雨崔晓宁张馨鹤 School of Physics and Technology University of JinanJinan 250022China Marketing Service Center(Center of Metrology) State Grid ShanDong Electric Power CompanyJinan 250001China

In a two-frequency cavity driving and atom driving atom-cavity system,we find the photon blockade effect.In a truncated eigenstates space,we calculate the zero-delay second-order correlation function of the cavity mode analytically and obtain an optimal condition for the photon blockade.By including three transition pathways,we find that higher excitations of the cavity mode can be further suppressed and the zero-delay second-order correlation function can be reduced additionally.Based on the master equation,we simulate the system evolution and find that the analytical solutions match well with the numerical results.Our scheme is robust with small fluctuations of parameters and may be used as a new type of single photon source.

关键词： photon blockade single photon source quantum interference

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

High-sensitive state perception method for inverter-fed machine turn insulation based on FrFT-Mel

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Global Energy Interconnection 2024年第2期7卷 155-165页

作者： Ruitian Fan Xing Lei Tao Jia Menglong Qin Hao Li Dawei Xiang College of electrical power Engineering Shanghai University of Electric PowerShanghai 200090P.R.China state grid Shanghai Municipal electric power company Shanghai 200437P.R.China state grid Technology College Shandong 250002P.R.China College of Electronics and Information Engineering Tongji UniversityShanghai 201804P.R.China

Amidst the swift advancement of new power systems and electric vehicles,inverter-fed machines have progressively materialized as a pivotal apparatus for efficient energy conversion.Stator winding turn insulation failure is the root cause of inverter-fed machine breakdown.The online monitoring of turn insulation health can detect potential safety risks promptly,but faces the challenge of weak characteristics of turn insulation degradation.This study proposes an innovative method to evaluate the turn insulation state of inverter-fed machines by utilizing the fractional Fourier transform with a Mel filter(FrFT-Mel).First,the sensitivity of the high-frequency(HF)switching oscillation current to variations in turn insulation was analyzed within the fractional domain.Subsequently,an improved Mel filter is introduced,and its structure and parameters are specifically designed based on the features intrinsic to the common-mode impedance resonance point of the electrical machine.Finally,an evaluation index was proposed for the turn insulation state of inverter-fed machines.Experimental results on a 3kW permanent magnet synchronous machine(PMSM)demonstrate that the proposed FrFT-Mel method significantly enhances the sensitivity of turn insulation state perception by approximately five times,compared to the traditional Fourier transform method.

关键词： state perception Turn insulation Switching oscillation Fractional Fourier transform Mel filter

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

Defect Detection in c-Si Photovoltaic Modules via Transient Thermography and Deconvolution Optimization

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Chinese Journal of electrical Engineering 2024年第1期10卷 3-11页

作者： Zekai Shen Hanqi Dai Hongwei Mei Yanxin Tu Liming Wang state grid Hangzhou power Supply company State Grid Zhejiang Electric Power Co.Ltd.Hangzhou 310000China Huairou power Supply Branch State Grid Beijing Electric Power Co.Ltd.Beijing 101400China Tsinghua Shenzhen International Graduate School Tsinghua UniversityShenzhen 518055China

Defects may occur in photovoltaic(PV)modules during production and long-term use,thereby threatening the safe operation of PV power stations.Transient thermography is a promising defect detection technology;however,its detection is limited by transverse thermal diffusion.This phenomenon is particularly noteworthy in the panel glasses of PV modules.A dynamic thermography testing method via transient thermography and Wiener filtering deconvolution optimization is proposed.Based on the time-varying characteristics of the point spread function,the selection rules of the first-order difference image for deconvolution are given.Samples with a broken grid and artificial cracks were tested to validate the performance of the optimization method.Compared with the feature images generated by traditional methods,the proposed method significantly improved the visual quality.Quantitative defect size detection can be realized by combining the deconvolution optimization method with adaptive threshold segmentation.For the same batch of PV products,the detection error could be controlled to within 10%.

关键词： Photovoltaic module transient thermography point spread function deconvolution optimization quantitative detection

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

Multi-area Frequency-constrained Unit Commitment for power Systems with High Penetration of Renewable Energy Sources and Induction Machine Load

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Journal of Modern power Systems and Clean Energy 2024年第3期12卷 754-766页

作者： Leibao Wang Hui Fan Jifeng Liang Longxun Xu Tiecheng Li Peng Luo Bo Hu Kaigui Xie the state grid Hebei electric power Research Institute state Key Laboratory of power Transmission Equipment & System Security and New Technology Chongqing University

The increasing penetration of renewable energy sources(RESs) brings great challenges to the frequency security of power systems. The traditional frequency-constrained unit commitment(FCUC) analyzes frequency by simplifying the average system frequency and ignoring numerous induction machines(IMs) in load, which may underestimate the risk and increase the operational cost. In this paper, we consider a multiarea frequency response(MAFR) model to capture the frequency dynamics in the unit scheduling problem, in which regional frequency security and the inertia of IM load are modeled with high-dimension differential algebraic equations. A multi-area FCUC(MFCUC) is formulated as mixed-integer nonlinear programming(MINLP) on the basis of the MAFR model. Then, we develop a multi-direction decomposition algorithm to solve the MFCUC efficiently. The original MINLP is decomposed into a master problem and subproblems. The subproblems check the nonlinear frequency dynamics and generate linear optimization cuts for the master problem to improve the frequency security in its optimal solution. Case studies on the modified IEEE 39-bus system and IEEE 118-bus system show a great reduction in operational costs. Moreover, simulation results verify the ability of the proposed MAFR model to reflect regional frequency security and the available inertia of IMs in unit scheduling.

关键词： Security Frequency response Load modeling Indexes Costs Sensitivity power system dynamics