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International Conference on High Voltage Engineering and Application, ICHVE

作者： Yunxiao Zhang Chenning Yan Kai Wu Yuanxiang Zhou Tianfeng Zhang College of Electrical Engineering and Automation Fuzhou University Fuzhou Fujian China Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China The Wind Solar Storage Division of State Key Laboratory of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi China Electric Power Research Institute Anhui Electric Power Company of State Grid Hefei China

ISBN: (数字)9781665407502

ISBN: (纸本)9781665407519

Silicone rubber (SIR) has been widely used in the insulation of cable accessories due to its excellent performance. In this paper, pure SIR and nano $\boldsymbol{\text{Al}_2 \mathrm{O}_3 / \text{SIR}}$ composites are thermally aged for 0–80 days at $\boldsymbol{200^{\circ} \mathrm{C}}$ . The effects of long-term thermal aging on the space charge transport are analyzed. The results show that with the increase of thermal aging time, the accumulation of heteropolar charge of pure SIR and nano $\boldsymbol{\text{Al}_{2}\mathrm{O}_{3}/\text{SIR}}$ composites gradually decreases and changes to the accumulation of homopolar charge. Compared with pure SIR, the space charge accumulation of $\boldsymbol{\text{Al}_{2}\mathrm{O}_{3}/\text{SIR}}$ composites decreases significantly and changes little with the increase of thermal aging time. It is believed that when doped nano $\boldsymbol{\text{Al}_{2}\mathrm{O}_{3}}$ in SIR, the increase of carrier mobility and the introduction of metal oxides reacting with fallen free radicals to form stable compounds both lead to less space charge accumulation of $\boldsymbol{\text{Al}_{2}\mathrm{O}_{3}/\text{SIR}}$ composites.

关键词： Nanocomposites Impurities Metals High-voltage techniques Aging Space charge Thermal analysis

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Analysis and Design for Hydrogen-Fueled Cascade Solid Oxide Fuel Cell System

SSRN

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SSRN 2023年

作者： Liu, Peiyuan Zhang, Yongliang Zhu, Jianzhong Han, Minfang Sun, Kaihua Zhong, Haijun Zhang, XueRui State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Energy and Power Engineering Tsinghua University Beijing100084 China Xuzhou Huatsing Jingkun Energy Co. Ltd. Jiangsu Province 221005 China Petrochemical Research Institute China National Petroleum Corporation Beijing112206 China Institute of Process Engineering Chinese Academy of Sciences Beijing100190 China

Maximizing total fuel utilization is the key to improving the electrical efficiency of solid oxide fuel cell (SOFC) systems. The cascade system can achieve this effectively, but there are fewer studies on hydrogen-fueled cascade systems, and the determination of suitable rated power ratios needs a basis. Because of the characteristics of cascade systems, a fast model that can predict performance at low flow rates and low hydrogen partial pressures is required. Using multiple sets of experimental data, this study developed and validated an improved semi-empirical model, which accurately predicted the industrial-sized cell performance at different flow rates and hydrogen partial pressures. On this basis, the basic parallel and cascade system models were established. The effects of fuel flow rate, rated power ratio, split ratio, and constraints on the system performance were studied and analyzed, and the appropriate design and operation parameters of the cascade system were determined. The results indicated that the cascade system can significantly improve electrical efficiency compared to the parallel system by selecting suitable design parameters. In the example of a 10-kW rated power system design, the cascade system improved the electrical efficiency by over 9% at rated power compared to the parallel system. The results obtained provide valuable reference for related research and offer guidance for system design. © 2023, The Authors. All rights reserved.

关键词： Electrical efficiency

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Multi-Stage Expansion Planning for Decarbonizing Thermal Generation Supported Renewable power systems Using Hydrogen and Ammonia Storage

arXiv

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arXiv 2023年

作者： Yu, Zhipeng Lin, Jin Liu, Feng Li, Jiarong Chi, Yingtian Song, Yonghua Ren, Zhengwei State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100087 China Sichuan Energy Internet Research Institute Tsinghua University Chengdu610213 China Department of Electrical and Computer Engineering University of Macau 999078 China Department of Electrical Engineering Tsinghua University Beijing100087 China

—Large-scale centralized development of wind and solar energy and peer-to-grid transmission of renewable energy source (RES) via high voltage direct current (HVDC) has been regarded as one of the most promising ways to achieve goals of peak carbon and carbon neutrality in China. Traditionally, large-scale thermal generation is needed to economically support the load demand of HVDC with a given profile, which in turn raises concerns about carbon emissions. To address the issues above, hydrogen energy storage system (HESS) and ammonia energy storage system (AESS) are introduced to gradually replace thermal generation, which is represented as a multi-stage expansion planning (MSEP) problem. Specifically, first, HESS and AESS are established in the MSEP model with carbon emission reduction constraints, and yearly data with hourly time resolution are utilized for each stage to well describe the intermittence of RES. Then, a combined Dantzig-Wolfe decomposition (DWD) and column generation (CG) solution approach is proposed to efficiently solve the large-scale MSEP model. Finally, a real-life system in China is studied. The results indicate that HESS and AESS have the potential to handle the intermittence of RES, as well as the monthly imbalance between RES and load demand. Especially under the goal of carbon neutrality, the contribution of HESS and AESS in reducing levelized cost of energy (LCOE) reaches 12.28% and 14.59%, respectively, which finally leads to a LCOE of 0.4324 RMB/kWh. Copyright © 2023, The Authors. All rights reserved.

关键词： Carbon

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Probabilistic Energy Consumption Estimation for Electric Buses

Probabilistic Energy Consumption Estimation for Electric Bus...

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Smart power & Internet Energy systems (SPIES), International Conference on

作者： Jingfei Jiang Bo Bao Fanzhuo Meng Yifan Ma Hui Zhang Yucheng Jin Fengwen Pan Xinmei Yuan State Key Lab. of Automotive Simulation and Control Jilin University Changchun China Changchun Automotive Test Center Co. Ltd. Changchun China Weichai Power Co. Ltd. Weifang China

Electric buses play a vital role in future sustainable transportation and estimating the energy consumption of electric buses is important for reducing range anxiety and optimizing charging schedules. However, due to the numerous unobserved factors in real-world driving, there are naturally significant uncertainties in the energy consumption of electric vehicles. Therefore, besides focusing on improving model accuracy, the estimating probabilistic distribution of the uncertainties can also help to better characterize electric bus energy consumption and increase the confidence in the estimation results. In this paper, two probabilistic models, based on Bayesian regression and quantile regression, are proposed to estimate the probabilistic distribution of electric bus energy consumption; the probabilistic models are trained and validated using real-world driving data from 10 electric buses over a year. The results show that the proposed methods both capture the probabilistic characteristics well; however, the variations of uncertainties are better adapted in quantile regression.

关键词： Temperature measurement Energy consumption Adaptation models Uncertainty Atmospheric modeling Estimation Probabilistic logic

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Optimal Sizing of Isolated Renewable power systems with Ammonia Synthesis: Model and Solution Approach

arXiv

引用

arXiv 2023年

作者： Yu, Zhipeng Lin, Jin Liu, Feng Li, Jiarong Zhao, Yuxuan Song, Yonghua The State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100087 China Sichuan Energy Internet Reasearch Institute Tsinghua University Chengdu610213 China The Department of Electrical and Computer Engineering University of Macau 999078 China The Department of Electrical Engineering Tsinghua University Beijing100087 China

Isolated renewable power to ammonia (IRePtA) has been recognized as a promising way to decarbonize the chemical industry. Optimal sizing of the renewable power system is significant to improve the techno-economic of IRePtA since the investment of power sources exceeds 80% of the total investment. However, multi-timescale electricity, hydrogen, and ammonia storages, minimum power supply for system safety, and the multiyear uncertainty of renewable generation lead to difficulties in planning. To address the issues above, an IGDT-MILFP model is proposed. First, the levelized cost of ammonia (LCOA) is directly formulated as the objective, rendering a mixed integer linear fractional programming (MILFP) problem. Information gap decision theory (IGDT) is utilized to handle the multiyear uncertainty of renewable generation. Second, a combined Charnes-Cooper (C&C) transformation and Branch-and-Bound (B&B) method is proposed to efficiently solve the large-scale IGDT-MILFP model, giving robust and opportunistic planning results. Then, Markov Chain Monte Carlo (MCMC) sampling-based posteriori analysis is leveraged to quantify the long-run performance. Finally, a real-life system in Inner Mongolia, China, is studied. The results indicate that the proposed methods could reduce the computational burden by orders of magnitude for solving a large-scale MILFP problem. Moreover, the proposed IGDT-MILFP model is necessary and accurate to obtain an optimal capacity allocation with the lowest expected LCOA (3610 RMB/t) in long-run simulations. Copyright © 2023, The Authors. All rights reserved.

关键词： Ammonia

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Multiple-Stage Inter-temporal Flexibility for Planning: A Non-sequential Probabilistic Production simulation Approach

Multiple-Stage Inter-temporal Flexibility for Planning: A No...

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power, Energy and Electrical Engineering (CPEEE), International Conference on

作者： Ying Qiao Haibo Li Jiheng Jiang Guobin Fu State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China Sichuan Energy Internet Research Institute Tsinghua University Chengdu China State Grid Qinghai Provincial Electric Power Company Xining China

ISBN: (数字)9781728177175

ISBN: (纸本)9781728177182

High wind energy curtailment during winter and early spring in north China has drawn widespread concern in recent years, which, at source, results from the shortage of power system flexibility. Therefore, power system needs to consider the flexibility in planning stage. However, current flexibility metric is difficult to calculate and be applied in to the optimal planning. A non-sequential production simulation model with only input data of the cumulative probability function and/or probability density function of heat demand, electricity demand, and wind power is proposed, which is used to obtain the probability distribution of the production for generators according to least cost principle. Then the flexibility metric can be easily calculated based on the production results. simulations were performed based on the actual data of a large wind power zone in north China. Multiple flexibility metric was evaluated and compared with the wind power curtailment, which shows the strong correlation between them. Finally, the impact of flexible resources on the flexibility metric was analyzed.

关键词： Measurement Production Wind power generation Data models Planning Space heating Resistance heating

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Intrinsic Insight of Energy-Efficiency Optimization for Co2 Capture by Amine-Based Solvent: Effect of Mass Transfer and Solvent Regeneration

SSRN

引用

SSRN 2022年

作者： Chen, Zhen Yuan, Bingling Zhan, Guoxiong Li, Yuchen Wang, Lidong You, Changfu Li, Junhua State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Beijing100084 China Key Laboratory for Thermal Science and Power Engineering the Ministry of Education Department of Energy and Power Engineering Tsinghua University Beijing100084 China MOE Key Laboratory of Resources and Environmental Systems Optimization Department of Environmental Science and Engineering North China Electric Power University Beijing102206 China

Here the energy-efficiency performance of CO2 capture is investigated based on bench-scale continuous absorption-desorption system. A comprehensive evaluation is performed by L25(65) orthogonal tests to analyze the effects of operating conditions on CO2 capture. With combination of Eulerian-Eulerian method with the population balance model, we predict the dynamics evolution process of dispersed bubble, in order to provide the detailed information of interphase contact area and multiphase flow for modelling complete mass transfer parameters. Meanwhile, rigorous process simulation is developed to analyze the energy consumption of carbon capture. Experiments reveal desorption temperature and flue gas flow play a major role for CO2 capture efficiency. Rising flue gas flow could promote interfacial area, but decreases contact time, overally, net CO2 flow approximately determines the linear relationship of capture efficiency and absorption rate. Higher desorption temperature provides leaner solvent to drive CO2 absorption, but consumes greater energy penalty for CO2 capture. © 2022, The Authors. All rights reserved.

关键词： Mass transfer

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An Iterative-Correction Approach of Risk-Constrained Unit Commitment of power systems with Wind power based on Optimal Reserve Decision

An Iterative-Correction Approach of Risk-Constrained Unit Co...

引用

power, Energy and Electrical Engineering (CPEEE), International Conference on

作者： Ying Qiao Yisha Lin Haibo Li Xuebin Wang State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China Sichuan Energy Internet Research Institute of Tsinghua University Chengdu China State Grid Qinghai Electric Power Co. Ltd Xining China

ISBN: (数字)9781728177175

ISBN: (纸本)9781728177182

The operation risk may increase with the high penetration of wind power, but the calculation of risk indices is complex and nonlinear, which makes it difficult to incorporate the risk constraints into the conventional unit commitment (UC) model. This paper focuses on accurately handling the risk constraints instead of approximate exponential decay rules, and proposes an iteration-correction methodology to solve risked-constrained UC of power systems with wind power. The proposed method calculates the risk indices based on the PJM method, and modifies the minimum reserve demand in each iterative step if the risk indices exceed the limits. A dynamic iterative speed-up equation is given to decrease the elapsed time. The case studies based on the actual system of China are conducted to validate the effectiveness. Compared with the conventional reserve limit, the precise and optimal reserve decision is made under different risk levels, and the proposed UC has merits of less cost and lower risk.

关键词： Uncertainty power system dynamics Wind power generation power grids Mathematical model Iterative methods Optimization

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Ultra-short-term solar power forecasting based on a modified clear sky model

Ultra-short-term solar power forecasting based on a modified...

引用

Chinese control Conference (CCC)

作者： Yuan Ma Xuemin Zhang Shengwei Mei Zhao Zhen Rui Gao Zijie Zhou State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

ISBN: (数字)9789881563903

ISBN: (纸本)9781728165233

The ultra-short-term prediction of photovoltaic power system is of great significance to the safe operation of power system. However, the daily and annual periodicity of solar radiation brings strong non-stationary to the photovoltaic power series, which makes it difficult to predict the photovoltaic power series. In order to overcome the problem that the detailed clear sky model relies on a large number of plant parameters, this paper proposes a prediction algorithm based on a modified clear sky model. Firstly, historical data and geographical location of a certain site are utilized to build a modified clear sky model, then the theoretical clear sky power curve fitted by the modified clear sky model are divided by the actual historical power output to get a stabilized time series, finally the method of "online update" is adopted to forecast PV plant power output in the ultra-short-term time horizon (0-4 h). The test results of a photovoltaic power station in Ningxia show that the proposed model can reduce the prediction error of the 4th hour to about 3%.

关键词： Photovoltaic systems Predictive models Data models Mathematical model Forecasting

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Switching Current Imbalance Mitigation for Paralleled SiC MOSFETs Using Common-mode Choke in Gate Loop

Switching Current Imbalance Mitigation for Paralleled SiC MO...

引用

IEEE Energy Conversion Congress and Exposition

作者： Jiye Liu Zedong Zheng State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

ISBN: (数字)9781728158266

ISBN: (纸本)9781728158273

Paralleling SiC MOSFETs is a popular way to increase the current capacity. However, due to asymmetric layout, device parameter mismatch and other factors, imbalanced switching or dynamic current is observed among the paralleled switches in multi-device paralleling application which results in unequal switching loss, challenging the security and reliability of the system. In this paper, a common-mode choke in the gate loop is proposed and analyzed to suppress the imbalanced switching current induced by asymmetric layout in a half-bridge configuration with a Kelvin-source connection. The mechanism of the proposed method is comprehensively investigated to show that though the common-mode choke is placed in the gate loop, it can also mitigate the imbalanced current caused by asymmetric power loop. And it also shows that only the leakage inductance of the choke is seen in the gate loop and thus the switching speed is not expected to be influenced. The proposed method can be easily extended to multi-device paralleling application and the switching transients is hardly influenced by the common-mode choke. simulation and experimental results are presented to verify the proposed method.

关键词： Inductance MOSFET Silicon carbide Switches Logic gates Inductors Transient analysis

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