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arXiv 2022年

作者： Qi, Ruomei Li, Jiarong Lin, Jin Song, Yonghua Wang, Jiepeng Cui, Qiangqiang Qiu, Yiwei Tang, Ming Wang, Jian State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China Tsinghua-Sichuan Energy Internet Research Institute Chengdu China Department of Electrical and Computer Engineering University of Macau China School of Materials Science and Engineering Shanghai University Shanghai China Purification Equipment Research Institute of CSIC Handan China College of Electrical Engineering Sichuan University Chengdu China

Thermal management is vital for the efficient and safe operation of alkaline electrolysis systems. Traditional alkaline electrolysis systems use simple proportional-integral-differentiation (PID) controllers to maintain the stack temperature near the rated value. However, in renewable-to-hydrogen scenarios, the stack temperature is disturbed by load fluctuations, and the temperature overshoot phenomenon occurs which can exceed the upper limit and harm the stack. This paper focuses on the thermal modelling and controller design of an alkaline electrolysis system under dynamic operating conditions. A control-oriented thermal model is established in the form of a third-order time-delay process, which is used for simulation and controller design. Based on this model, we propose two novel controllers to reduce temperature overshoot: one is a current feed-forward PID controller (PID-I), the other is a model predictive controller (MPC). Their performances are tested on a lab-scale system and the experimental results are satisfying: the temperature overshoot is reduced by 2.2◦C with the PID-I controller, and no obvious overshoot is observed with the MPC controller. Furthermore, the thermal dynamic performance of an MW-scale alkaline electrolysis system is analyzed by simulation, which shows that the temperature overshoot phenomenon is more general in large systems. The proposed method allows for higher temperature set points which can improve system efficiency by 1%. © 2022, CC BY.

关键词： controllers

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Study on probability of voltage instability based on the stochastic characteristic of load margin index

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2006年第13期26卷 26-30页

作者： Dai, Jian-Feng Wang, Hai-Chao Zhou, Shuang-Xi Lu, Zong-Xiang Zhu, Ling-Zhi State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Beijing 100084 China

In order to make up the deficiency of traditional analytical method used in the research of voltage stability problem, we need to know the probability information concerned with voltage instability. Therefore, this paper proposes a method to calculate the probability of voltage instability based on the stochastic characteristic of load margin index. This method firstly determines the stochastic characteristic of load margin index through an analysis about the randomicity of parameters which tie up with the tracing of critical point in continue power flow computation, and then figures out the probability of voltage instability by using moment and cumulate method. Owing to take into account more uncertain factors' influence on the voltage stability, the result acquired by this method is much more accurate and reasonable. A numerical simulation based on IEEE 39-bus system reveals that the proposed method works properly.

关键词： Electric power systems

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Experimental Investigation of Fuel Starvation on Industrial-Sized Solid Oxide Fuel Cells Using Segmented Cathodes and Area Specific Resistances

SSRN

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SSRN 2022年

作者： Zhang, Jihao Guo, Huding Lei, Libin Shen, Shuanglin Zheng, Keqing Han, Minfang Laboratory of Hydrogen Energy and Fuel Cells School of Low-Carbon Energy and Power Engineering China University of Mining and Technology Xuzhou221116 China Xuzhou Huatsing Jingkun Energy Co. Ltd. Xuzhou221005 China Smart Energy Research Center School of Materials and Energy Guangdong University of Technology Guangzhou510006 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Energy and Power Engineering Tsinghua University Beijing100084 China

Fuel starvation needs to be timely detected to avoid anode oxidation, especially for industrial-sized Solid oxide fuel cells (SOFCs). In this work, a novel and useful segmented cell measurement method is developed to detect fuel starvation occurring in local regions. For this developed method, the cathode of SOFCs is segmented and only the voltage signal is measured in the segments. Then, the local current-voltage (I-V) curve of each segment is determined using the measured voltage together with the global I-V curve. To validate the data reliability, area specific resistances (ASRs) are calculated and compared among different segments. Varieties of current loading rates and fuel flow rates are correspondingly investigated. Furthermore, the occurrence of fuel starvation is identified using the rapid voltage drop in I-V curves as well as the rapid ASR increment in I-ASR curves. The results show that compared to the voltage drop, the intrinsic ASR increment is a more sensitive and robust criterion to identify the occurrence of fuel starvation. This work will considerably benefit the progress of segmented cell measurements and local fuel starvation identifications. © 2022, The Authors. All rights reserved.

关键词： Cathodes

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Maximum flow algorithm based on adjustment of net flow on nodes and its application

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2008年第SUPPL.期28卷 31-34页

作者： He, Guang-Yu Sun, Ying-Yun Chen, Chao State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

For calculating the maximum capacity transported from source node to sink node in a network, a maximum flow algorithm was proposed. Based on the concept of net flow on nodes (NFN) and layered increment network (LIN), the plus flow process (PFP) and minus flow process (MFP) on LIN were defined. By performing PFP and MFP on NLP over and over, the maximum flow problem was solved when the sink node can't get a mark again. Compare to the existing max flow algorithm, the proposed method needs no complex data structure in processing, which makes the algorithm implemented easily. Based on the algorithm, a thermal economic dispatch software package which includes fixed electricity plant was developed and had been put into practice and had a good performance. Furthermore, the algorithm runs in O(n2m) (n, m is the number of nodes and arcs of the network) was proved.

关键词： Scheduling

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Optimal power System Scheduling Considering Uncertainty-Induced generation Unit Output Curtailment

Optimal Power System Scheduling Considering Uncertainty-Indu...

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System simulation Technology and its Application (CCSSTA), IEEE China Conference on

作者： Wei Hu Ning Mi Hailiang Zhong Weihan Chen Kun Ma Tianxiang Geng Yun Wang Bo Su Long Yang State Key Laboratory of Power System and Generation Equipment(Department of Electrical Engineering) Tsinghua University Beijing China Dispatching Control Center State Grid Ningxia Electric Power Co. Ltd. Yinchuan China Department of Electrical Engineering and Applied Electronic Technology Tsinghua University Beijing China

ISBN: (数字)9798350366600

ISBN: (纸本)9798350366617

Under the call of the national “dual carbon” goals, the growth of the proportion of new energy generation has become an inevitable trend in energy structure adjustment. The “static parameter” model, which traditional thermal power units rely on, can no longer accurately reflect their output uncertainty, urgently requiring a new optimization scheduling strategy to cope with this change. This study proposes an optimized scheduling model for power generation systems that considers the output curtailment and unplanned outages of thermal power units. It employs non-parametric kernel density estimation techniques to model the uncertainty of thermal power unit output and uses chance constraints to define the fluctuation range of generation output and the system’s reliability. The model adopts a scenario generation method based on Copula theory to construct output scenarios and further employs reduction techniques to optimize the number of scenarios. Moreover, this paper introduces Conditional Value at Risk as a key indicator to measure the cost of system uncertainty risk, thereby providing a more comprehensive perspective in risk assessment. simulation experiments on the IEEE 30-node standard system demonstrate that compared to traditional optimization scheduling models relying on static parameters, the proposed model can more effectively balance the output fluctuations of different thermal power units, significantly reducing the risk of curtailment due to supply shortages. This study offers a new theoretical basis and practical guidance for optimizing the scheduling of power systems under the context of large-scale integration of new energy and economic fluctuations.

关键词： Uncertainty Fluctuations Costs Estimation Thermal management systems simulation Scenario generation Kernel Optimization Standards

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Annual renewable energy planning platform: Methodology and design

Annual renewable energy planning platform: Methodology and d...

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IEEE International Conference on Automation Science and Engineering (CASE)

作者： Fangdi Zeng Zhaohong Bie Xiaofei Li Zifen Han Yong Zhi Yankai Zhang School of Electrical Engineering Xi'an Jiaotong University State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong University China State Key Laboratory of Operation and Control of Renewable Energy & Storage Systems China Electric Power Research Institute Beijing China State Grid Gansu Electric Power Company Lanzhou China Electric Power Research Institute State Grid Gansu Electric Power Company Lanzhou China

With the popularity of computer and internet technology applied in the energy internet, the development of a new platform for renewable energy planning is on the way as a response to the increase of the percentage of renewable energy in energy mix. An annual renewable energy planning platform is designed in this paper. The method based on time sequential simulation is used and an optimization with the objective to maximize the renewable energy accommodation is proposed for the decision making of annual renewable energy planning. The framework of the platform is presented and database technology is applied to realize the software interface for the data share between the renewable energy planning platform and other software. Additionally, a case test is presented to show the effect of the method.

关键词： Renewable energy sources power systems Wind power generation Planning Hydroelectric power generation Companies Software

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Unit Commitment Considering Demand Response Behavior Based on Utility Maximization

Unit Commitment Considering Demand Response Behavior Based o...

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IEEE Conference on Energy Internet and Energy System Integration

作者： Yumin Zhang Xueshan Han Bo Xu Li Zhang Donglei Sun Xiaofeng Miao Jiayin Jiang Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education Shandong University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment (Department of Electrical Engineering Tsinghua University) Economic & Technology Research Institute of State Grid Shandong Electric Power Company State Grid Shandong Electric Power Company Yantai Electric Power Company

ISBN: (纸本)9781538614280

The active participation of demand side resources in power grid operation not only benefits the individual participant but also benefits the whole system. The optimal goal can promote by excavating the active behaviors of demand side. The welfare maximization of market participant is the driving force of such active behaviors. Considering the independence of each user's behavior, the consumer's utility function is selected to depict consumer's preference and demand response behavior. In order to coordinate the consumers' maximum welfare with social welfare maximization, consumers' utility function and units' operation cost are integrated into Unit Commitment (UC) model. The objective function is to maximize social welfare, by subtracting units' operation cost from consumers' total utility, and this objective can be acquired. Considering the proposed model should be solved in a distributed manner, the idea of the centralized coordination and the decentralized decision-making is proposed. Based on the Lagrangian relaxation (LR) principle and distributed real-time pricing scheme, a closed-loop feedback mechanism is constructed to reflect the relationship among generator output, price level, and load demand. The ten generating units example can illustrate the effectiveness of the proposed method.

关键词： Demand utility Decomposition coordination Electricity market Lagrangian relaxation Real-time pricing Unit commitment

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Eigenvalue analysis of multi-mode sub-synchronous resonance for multimachine plant-to-grid transmission systems with fixed series compensation

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2008年第SUPPL.期28卷 13-18页

作者： Zhang, Shu-Qing Xie, Xiao-Rong Yang, Ting-Zhi Liu, Shi-Yu State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

For some domestic large thermal power plants delivering electric energy over long distances, the sub-synchronous resonance (SSR), which is induced by the fixed series compensation (FSC), attracts much attention. Eigenvalue analysis is one of the primary methods to assess the risk and explore the countermeasure. However, for handling multi-machine and multi-mode SSR problems, no practical toolkit based on eigenvalue analysis is on hand for the moment. In this paper, a systematic modeling approach and analysis flows for the purpose of eigenvalue analysis of multimachine plant-to-grid transmission systems with FSC were proposed. The equating technique of machines and networks was presented, and the effect of the q-axis damping windings on the SSR was also explored. The applicability of the proposed method was verified with an actual multimachine system. Furthermore, its advantage over existing SMIB based eigenvalue analysis was clarified by a comparative study between the original multi-machine system and the simplified single-machine system.

关键词： Eigenvalues and eigenfunctions

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Nanosecond-pulse Dielectric Barrier Discharge Using Magnetic Compression Solid-state Pulsed power

Nanosecond-pulse Dielectric Barrier Discharge Using Magnetic...

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IEEE International power Modulator and Hogh Voltage Conference

作者： Tao Shao Yang Yu Cheng Zhang Zheng Niu Dongdong Zhang Jue Wang Yaohong Sun Ping Yan Yuanxiang Zhou Institute of Electrical Engineering Chinese Academy of Sciences State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Electrical Engineering Department Tsinghua University

ISBN: (纸本)9781424471317

Dielectric barrier discharge excitated by unipolar pulsed power is a promising approach for producing non-thermal plasma at atmospheric pressure. A magnetic compression solid-state pulse power generator is used to produce dielectric barrier discharge (DBD). The generator is capable of providing repetitive pulses with the voltage of up to 30 kV and duration of 70 ns at a 300 Ω resistive load. This paper illustrates electrical characteristic and luminous emissions of DBD excitated by repetitive unipolar nanosecond-pulses in atmospheric air. Different from common DBD excitated by high-voltage AC sources, discharge current of DBD in the experimental investigation can be on an order of tens of amperes. When the DBD is created using two liquid electrodes, the luminous emissions from the obverse and flank sides of liquid electrodes show that no filament is observed and the discharge is homogeneous and diffuse in the whole discharge regime.

关键词： Dielectric barrier discharge Pulsed power Magnetic compression Repetitive nanosecond pulses Atmospheric pressure air Gas discharge Homogeneous discharge

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Boosting Co2 Absorption and Desorption of Biphasic Solvent by Nanoparticles for Efficient Carbon Dioxide Capture

SSRN

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SSRN 2023年

作者： Yuan, Bingling Zhan, Guoxiong Xing, Lei Li, Yuchen Huang, Zhoulan Chen, Zhen Wang, Lidong Li, Junhua MOE Key Laboratory of Resources and Environmental Systems Optimization Department of Environmental Science and Engineering North China Electric Power University Beijing102206 China State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Beijing100084 China

Introduction of nanoparticles (NPs) in the solvent was treated an efficient route to enhance mass and heat transfer, therefore, it was a promising strategy to boost carbon dioxide (CO2) absorption and desorption, especially for the biphasic solvent with weak absorption rate and low heat capacity. Herein, powder TiO2 and SiO2 with nanoscale was selected to prepare nanofluid for CO2 capture, based on DMPA-NHD biphasic solvent. The stability of nanofluid and the effect of NPs on CO2 absorption-desorption, phase-splitting was comprehensively explored in this work. Experimental results revealed that 0.06wt% 60nm TiO2 presented excellent performance for CO2 absorption. The liquid film resistance decreased by 11% after introducing NPs, therefore, the maximum mass transfer coefficient is 1.7×10-10 mol·cm-2·s-1·Pa (at 40 °C), increasing by 27% than the blank. In addition, 0.06wt% 50nm SiO2 leaded to significant promotion for CO2 desorption, with the maximum desorption rate at 3.9 mmol/min, and the desorption energy consumption reduced by 9.5% compared with blank case. Importantly, introduction of NPs had no significant effect on the phase splitting behavior, according to the time-profile phase-splitting measurements. The influence of NPs on biphasic solvent behavior was firstly explored to provide a reference for subsequent practice application. © 2023, The Authors. All rights reserved.

关键词： Carbon dioxide

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