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International Conference on power Electronics and Motion control (IPEMC)

作者： Jiamei Zhang Kai Sun State Key Lab of Power System Operation and Control Tsinghua University Beijing

ISBN: (数字)9798350351330

ISBN: (纸本)9798350351347

The proliferation of distributed photovoltaics and electric vehicles in distribution network (DN) has led to differentiation of the same region, which may result in voltage exceeding the limits and unbalanced branch flow. At the same time, soft open point (SOP) is replacing traditional interconnect switches with greater flexibility and controllability. This paper proposes a SOP based regional balanced optimization scheduling method for distribution networks. In the optimal model, the distribution network division method is proposed based on the sensitivity analysis and system general controllable capability index. An optimization model is constructed to minimize the operation costs within the region while the voltage is within the safe range based on the active and reactive power control of SOPs. The nonlinear factors are converted into linearized based on piecewise linearization and second-order cone optimization methods. The superiority of the proposed method is proved through comparative case analysis.

关键词： Photovoltaic systems Reactive power control Sensitivity analysis Distribution networks Optimal scheduling Electric vehicles power electronics

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Numerical Simulation of Streamer Discharge in Transformer Oil Under Various Ionization Energies 19th

Numerical Simulation of Streamer Discharge in Transformer Oi...

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19th Annual Conference of China Electrotechnical Society, ACCES 2024

作者： Bao, Yanyan Liang, Shaobin Wang, Feng Zhang, Guangdong Chen, Jianning Zhou, Yuanxiang State Grid Gansu Electric Power Research Institute Lanzhou730070 China State Key Laboratory of Power System Operation and Control Beijing100084 China Department of Electrical Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9789819613786

Discharge in transformer oil is one of the primary causes of transformer failures. The physical mechanisms of oil discharges are not yet fully understood. Scholars have simulated the discharge process with electrodynamics model, but there is limited research on how the ionization energy, which changes due to various factors such as components and temperature of transformer oil, affect the streamer discharge characteristic. To improve the mechanism of discharge in transformer oil, this paper adopts an electrohydrodynamic model to study the impact of different ionization energies on the streamer discharge characteristics of transformer oil, including initiation voltage, discharge voltage, development speed, and electric field strength. When the ionization energy is between 6.1 eV and 8.1 eV, the initiation voltage and discharge voltage increase linearly with the ionization energy. Within the range of 7.1 eV to 8.1 eV, the time in the streamer accumulation phase increases exponentially with the ionization energy, while the streamer development speed decreases. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Electrohydrodynamics

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Feasibility study of renewable e-methanol production:A substitution pathway from blue to green

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iEnergy 2024年第2期3卷 108-114页

作者： Peiyang Li Jin Lin Zhipeng Yu Yingtian Chi Kai Zhao State Key Laboratory of Power System Operation and Control Department of Electrical EngineeringTsinghua UniversityBeijing 100087China Tsinghua-Sichuan Energy Internet Research Institute Chengdu 610213China Beijing Representative Office of Methanol Institute Beijing 100020China

Producing renewable e-methanol from e-hydrogen and diverse carbon sources is an essential way for clean methanol *** this,the technical and economic feasibility of different e-methanols has yet to be thoroughly compared,leaving the most promising pathway to achieve commercialization yet *** paper reports a preliminary analysis of the lifecycle greenhouse gas(GHG)emissions and costs of four renewable e-methanols with different carbon sources:bio-carbon,direct air capture(DAC),fossil fuel carbon capture(FFCC),and *** results indicate that renewable e-methanol costs(4167−10250 CNY/tonne)2−4 times the market rate of grey ***,with the carbon tax and the projected decline in e-H2 costs,blue e-methanol may initially replace diesel in inland navigation,followed by a shift from heavy fuel oil(HFO)to green e-methanol in ocean ***,the e-H2 cost and the availability of green carbon are vital factors affecting cost-effectiveness.A reduction in e-H2 cost from 2.1 CNY/Nm3 to 1.1 CNY/Nm3 resulting from a transition from an annual to a daily scheduling period,could lower e-methanol costs by 1200 to 2100 *** paper also provides an in-depth discussion on the challenges and opportunities associated with the various green carbon sources.

关键词： Renewable energy e-methanol e-hydrogen green carbon source chemical process flexibility

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Inertia Support Strategy for DC Collecting system of Wind Turbine Generator

Inertia Support Strategy for DC Collecting System of Wind Tu...

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2024 CPSS and IEEE International Symposium on Energy Storage and Conversion, CPSS and ISESC 2024

作者： Liu, Zenyang Sun, Kai Wang, Huan Lu, Junlong Tsinghua University State Key Laboratory of Power System Operation and Control Department of Electrical Engineering Beijing China Institute of Electrical Engineering Chinese Academy of Sciences Renewable Energy Power Generation System Research Department Beijing China

ISBN: (纸本)9798350380514

In wind turbine generators system, lacking of inertia is a common problem. In AC collecting system, some researches have been done to solve this problem. However, in DC collecting system, few researches were done. This paper analyzes the analogies between AC and DC collecting system and the virtual capacitor control corresponding to the virtual synchronous generator control. Small signal models of different precision are proposed considering the LLC resonant converter used for stepping-up. The virtual capacitance provided by the control is calculated using the small signal model and this verifies the effectiveness of the control quantitively and demonstrates that the small signal models are useful. © 2024 IEEE.

关键词： Wind Turbine Generators

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Software and hardware design of microcomputer relay protection device based on DSP 2

Software and hardware design of microcomputer relay protecti...

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2023 2nd International Conference on power system and power Engineering, PSPE 2023

作者： Huo, Jingchong Meng, Runquan Li, Shengwen Liu, Qiang Shanxi Key Lab of Power System Operation and Control Taiyuan University of Technology Taiyuan030024 China Electric Power Research Institute State Grid Shanxi Electric Power Company Taiyuan030001 China

The research on fault protection technology of AC power grid in AC/DC hybrid microgrid is very mature, while the research on fault protection technology of DC microgrid is still in the development stage. Therefore, the research and development of necessary power electronics and protection devices have become a research hotspot in recent years. In this paper, a microcomputer protection device based on the TMS320F28335 chip is developed. Considering the anti-interference of field use, detailed hardware and software design is carried out. The debugging effect is good, and the low-voltage DC short-circuit fault protection function can be reliably realized. © Published under licence by IOP Publishing Ltd.

关键词： Microcomputers

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Effect of Photoionization Mechanism on Numerical Simulation of Transformer Oil Streamer Discharge 19th

Effect of Photoionization Mechanism on Numerical Simulation ...

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19th Annual Conference of China Electrotechnical Society, ACCES 2024

作者： Liang, Shaobin Zhou, Yuanxiang Chen, Jianning He, Zhiyang Li, Yuhang School of Electrical Engineering Xinjiang University Urumqi China State Key Laboratory of Power System Operation and Control Beijing China Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9789819613861

Discharge in transformer oil is one of the primary causes of transformer failures. The physical mechanisms of oil discharges are not yet fully understood. However, the prevailing electrohydrodynamics models primarily adopt field ionization and collision ionization, neglecting photoionization, which could potentially affect the discharge of liquid dielectric streamers. To reveal the discharge characteristics of transformer oil, this paper improves the field ionization term in electrohydrodynamics model, establishes a function of the ionization energy of transformer oil in relation to the recombination strength of carriers, and proposes a simulation model of streamer discharge in oil considering photoionization. The effects of photoionization on the characteristics of streamer discharge in transformer oil are studied, by examining the morphology and propagation velocity of streamers. The results show that the introduction of the photoionization mechanism promotes the formation of streamer branches and makes the energy in the streamer channel more concentrated. Moreover, photoionization facilitates the rapid propagation of streamers, which is key to the formation of the third mode of streamers. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Electrohydrodynamics

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A data selection method for matrix effects and uncertainty reduction for laser-induced breakdown spectroscopy

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Plasma Science and Technology 2023年第7期25卷 82-89页

作者：龙杰宋惟然侯宗余王哲 State Key Laboratory of Power System Operation and Control Systems International Joint Laboratory on Low Carbon Clean Energy InnovationDepartment of Energy and Power EngineeringTsinghua UniversityBeijing 100084People’s Republic of China Shanxi Research Institute for Clean Energy Tsinghua UniversityTaiyuan 030032People’s Republic of China

Severe matrix effects and high signal uncertainty are two key bottlenecks for the quantitative performance and wide applications of laser-induced breakdown spectroscopy(LIBS).Based on the understanding that the superposition of both matrix effects and signal uncertainty directly affects plasma parameters and further influences spectral intensity and LIBS quantification performance,a data selection method based on plasma temperature matching(DSPTM)was proposed to reduce both matrix effects and signal *** selecting spectra with smaller plasma temperature differences for all samples,the proposed method was able to build up the quantification model to rely more on spectra with smaller matrix effects and signal uncertainty,therefore improving final quantification *** applied to quantitative analysis of the zinc content in brass alloys,it was found that both accuracy and precision were improved using either a univariate model or multiple linear regression(MLR).More specifically,for the univariate model,the root-mean-square error of prediction(RMSEP),the determination coefficients(R^(2))and relative standard derivation(RSD)were improved from 3.30%,0.864 and 18.8%to 1.06%,0.986 and 13.5%,respectively;while for MLR,RMSEP,R^(2)and RSD were improved from 3.22%,0.871 and 26.2%to 1.07%,0.986 and 17.4%,*** results prove that DSPTM can be used as an effective method to reduce matrix effects and improve repeatability by selecting reliable data.

关键词： laser-induced breakdown spectroscopy(LIBS) quantification uncertainty univariate/multivariate analysis matrix effects temperature matching

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Geometric Methods for Assessing the Value and Demands of Energy Storage in power system operation

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Energy Internet 2025年第1期2卷 86-103页

作者： Qi Lv Boshen Zheng Shengwei Mei Wei Wei Department of Electrical Engineering State Key Laboratory of Power System Operation and Control Tsinghua University Beijing China

Driven by the desire of a low-carbon society, the penetration level of renewable generation in the power grid of China will still grow fast in the near future. As the synchronised generators whose output is controllable are gradually replaced by volatile energy resources, energy storage is expected to play a vital role in regulation services and flexibility provision. Because the capital cost of energy storage is still relatively high, it is important to assess the value or demand of energy storage before making an investment decision. This paper presents two representative mathematical tools to achieve this target in a geometric fashion. The first one is the multi-parametric programming method. It depicts the reduced cost by deploying energy storage through post-optimal value function, which is easy to visualise or can be embedded in high-level optimisation problems such as storage sizing. The second one is a polyhedral projection method. It represents all feasible power-energy capacity pairs of a storage unit to achieve a certain target. The above methods remove the need of repeatedly solving a large number of problems with varying capacity parameters. Simple examples are given for illustration, and the presented methods can also directly handle problems with complex models and constraints.

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A Review on the Mullins Effect in Tough Elastomers and Gels

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Acta Mechanica Solida Sinica 2024年第2期37卷 181-214页

作者： Lin Zhan Shaoxing Qu Rui Xiao MOE Key Lab of Disaster Forecast and Control in Engineering College of Mechanics and Construction EngineeringJinan UniversityGuangzhou510632China State Key Laboratory of Fluid Power and Mechatronic System Key Laboratory of Soft Machines and Smart Devices of Zhejiang ProvinceDepartment of Engineering MechanicsZhejiang UniversityHangzhou310027China

Tough elastomers and gels have garnered broad research interest due to their wide-ranging potential ***,during the loading and unloading cycles,a clear stress softening behavior can be observed in many material systems,which is also named as the Mullins *** this work,we aim to provide a complete review of the Mullins effect in soft yet tough materials,specifically focusing on nanocomposite gels,double-network hydrogels,and multi-network *** first revisit the experimental observations for these soft *** then discuss the recent developments of constitutive models,emphasizing novel developments in the damage mechanisms or network *** phenomenological models will also be briefly *** attention is then placed on the anisotropic and multiaxial modeling *** is demonstrated that most of the existing models fail to accurately predict the multiaxial data,posing a significant challenge for developing future anisotropic models tailored for tough gels and elastomers.

关键词： Mullins effect Double-network hydrogels Nanocomposite gels Multi-network elastomers Anisotropic damage model Multiaxial model

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Preventive control Methods for power systems Based on Improved Deep Reinforcement Learning 6

Preventive Control Methods for Power Systems Based on Improv...

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6th International Conference on power and Energy Technology, ICPET 2024

作者： Zhang, Jie Zhu, Yihua Liang, Zhuohang Zhang, Qingqing Ma, Qinfeng Liu, Mingshun An, Su Dai, Jiang State Key Laboratory of HVDC Electric Power Research Institute China Southern Power Grid Guangzhou China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System Guangzhou China CSG Key Laboratory for Power System Simulation Electric Power Research Institute China Southern Power Grid Guangzhou China Power Dispatching and Control Center of Guizhou Power Grid Co. Ltd Guiyang China

ISBN: (纸本)9798350375855

Convergence speed, accuracy, generalization and decision transparency are very important indices for transient stability preventive control generation methods based on AI. This paper proposes a transient stability preventive control generation method based on graph deep reinforcement learning and its interpretation method using mutual information optimization. Firstly, a transient stability preventive control generation model is built based on the framework of deep reinforcement learning algorithm. The grid domain buses are mapped to the graph domain nodes and the grid graph data samples are generated. The graph convolutional neural network via initial residual and identity mapping (GCNII) is used to build the action network and the evaluation network. Secondly, based on the GCNII network, a transient stability assessment model is built and pre-trained, and graph data samples containing varies of topological structures and power flow states are applied to train the model. Then the interpretation method based on mutual information optimization is used to analyze the decision-making basis of the transient stability assessment model. The dominant factor affecting the transient instability of power system is extracted and its contribution degree is quantified, and the abduction analysis of transient stability is realized. Finally, the pre-trained transient stability assessment model is embedded in the deep reinforcement learning framework as a guide, and the power flow adjustment method is used to preferentially correct the weak factors and their influencing factors so that the transient stability prevention control strategies are obtained. The feasibility and effectiveness of the proposed method are verified in the IEEE-39 node test system. © 2024 IEEE.

关键词： Transient stability

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