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IEEE Electronic power Grid (eGrid)

作者： Liqiang Wang Bin Cao Qi Wang Yu Cong Haiyan Wu Zhang Xiaolin Institute of New Energy Technology Inner Mongolia Electric Power Research Institute Hohhot China Institute of Electric Power System Technology Inner Mongolia Electric Power Research Institute Hohhot China State Key Laboratory of Operation and Control of Renewable Energy & Storage Systems China Electric Power Research Institute Beijing China

ISBN: (数字)9781728157047

ISBN: (纸本)9781728157054

In order to prevent large-scale disconnection accidents of photovoltaic power stations caused by voltage fluctuations and faults in power grids, low voltage ride-through characteristics and other detection tests are needed when photovoltaic power stations are connected to power grids. At present, field test and type test are the main methods of detection, but due to the limitation of detection devices and test conditions, the evaluation of low voltage ride-through characteristics of photovoltaic power stations still remains in the single-machine detection mode, which ignores the interaction between photovoltaic inverters and inverters, inverters and static var generator(SVG) devices. The test results cannot truly reflect the low voltage traversing characteristics of the photovoltaic power stations. Using RT-LAB hardware-in-the-loop simulation platform, real photovoltaic inverters and SVG controllers are introduced to build simulation models of photovoltaic power stations. The differences between single-machine detection of photovoltaic inverters and reactive power compensation devices and low-voltage ride-through characteristics detection of the whole station are compared and studied. The simulation results show that, compared with the stand-alone test, the whole station simulation modeling test method can reflect the voltage rise caused by the reactive power characteristics of photovoltaic inverters and SVG devices after the drop, and more truly reflect the low voltage traversing characteristics of photovoltaic power stations.

关键词： Inverters Photovoltaic systems power system stability Low voltage Computational modeling

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Soft-sensing of NOx content in power Station based on BP Neural Network, RBF Neural Network and PCA-RBF Neural Network

Soft-sensing of NOx content in power Station based on BP Neu...

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2018 International Conference on Manufacturing Technology, Materials and Chemical Engineering, MTMCE 2018

作者： Hu, Peitao Changliang, Liu School of Control and Computer Engineering North China Electric Power University Baoding Hebei071003 China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Changping District Beijing102206 China

The timely and accurate measurement of the NOx content of the power plant denitrification system is very important for the precise regulation of the amount of ammonia and the control of the NOx emission. In this paper, we use 660MW coal-fired units as the research object. Combined with consideration of the poor accuracy and hysteresis of NOx measurement, the prediction models are established respectively by using RBF neural network, BP neural network and PCA-RBF neural network. The PCA-RBF model is based on principal component analysis (PCA) and RBF neural network. In order to improve the accuracy of the NOx soft-sensing model, this paper simplifies the sample model by optimizing the data samples, reducing the redundant information, and using dynamic neural network to achieve more accurate and faster training model. The results show that RBF neural network is superior to BP neural network in prediction accuracy and speed, while the improved and optimized PCA-RBF model has better prediction accuracy than the RBF neural network model. At the same time, this paper provides a theoretical basis for the real-time and accurate measurement of NOx content in power station, and provides some reference for improving the measurement and control of NOx in the actual production process. © Published under licence by IOP Publishing Ltd.

关键词： Principal component analysis

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Modeling of the Steam Pressure in Separator of a Once-through Unit Based on the ANN

Modeling of the Steam Pressure in Separator of a Once-throug...

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2018 International Conference on Manufacturing Technology, Materials and Chemical Engineering, MTMCE 2018

作者： Li, Yingqi Liu, Changliang School of Control and Computer Engineering North China Electric Power University Baoding Hebei071003 China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Changping District Beijing102206 China

It is challenging and interesting to establish a precise steam pressure in separator dynamic model of a once-through power plant unit in order to meet large scale load demands from the power grid and the needs of the engineering research. Steam pressure reveals the energy balance of boiler and turbine. This study proposes to establish such a steam pressure in separator mathematical model of a once-through boiler-turbine unit under dry operating conditions. Then the BP neural network model and the RBF neural network model were used to predict the steam pressure in separator, combined with running data. Moreover, in order to improve the performance of the network, the exhaustive method is used to optimize the parameters of the RBF network. After this, to further enhance model performance, the dynamic mathematical model was extended to be the one with different sets of parameters under different load ranges. More importantly, the dynamic model captures the essential dynamic characteristics of the unit. Therefore, the model can be feasible and applicable for simulation analysis and testing control algorithms. © Published under licence by IOP Publishing Ltd.

关键词： Separators

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Skin Effect and Eddy Current Loss in Electrical Steel Sheets under Applied Excitation Fields.

Skin Effect and Eddy Current Loss in Electrical Steel Sheets...

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International Conference on Magnetics (INTERMAG)

作者： J. Li Q. Yang S. Wang Y. Li State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China State Key Laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of Technology Tianjin China

Body: By applying electromagnetic diffusion equation, skin effect in electrical steel sheets in the condition of alternating excitation is analyzed based on Maxwell electromagnetic field theory. Due to skin effect is more significant mainly at high frequency, non-dimensionalized treatment for the diffusion equation is produced and eddy current loss is calculated by considering or not skin effect, respectively. Meanwhile, broadband magnetic losses and separation of typical electrical steel are obtained by using a 3-D magnetic properties testing system to bring to light the emergence of skin effect under rotational excitation. The simplification of magnetic constitutive equation is proposed and introduced into the diffusion equation, which is solved by employing finite elements coupled to Fredholm's equation. An approximate expression for the rotational eddy current loss component with skin effect is eventually written. The simulations show that due to the influence of skin effect, non-uniform distribution of induction flux density within electrical steel sheets will become more and more significant, the fl ux density and fi eld intensity nearby the surface are larger than that in the centre of the sheets [1, 2]. And with increasing of alternating excitation frequency, the inhomogeneity of induction flux density will be extended and growing more inhomogeneous, due to the smaller skin depth and a small increase of anomalous loss in the total core losses, as shown in Fig. 1.2. Therefore, alternating eddy current loss P as functions of the peak mean alternating flux density B mamean and the alternating excitation frequency f a can be deduced as follows: limv→∞P ae (B ma_mean f a )=[2ω a (B ma_mean ) 2 /3ρμν 2 =(σπ 2 d 2 /3ρ)(f a ) 2 (B ma_mean ) (no skin effect)[W/kg] (1) limν→0 P ae (B ma_mean f a )=[4ω a (B ma_mean ) 2 /ρμν=(4σ 1/2 π 3/2 d/ρμ 1/2 )(f a ) 3/2 (Bma_mean) 2 (considering significant skin effect) [W/kg] (2) where, ω a is the angular frequency; v = 2δ

关键词： Magnetics Conferences

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Fault Diagnosis of Wind Turbine Gearbox Based on Wavelet Transform

Fault Diagnosis of Wind Turbine Gearbox Based on Wavelet Tra...

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2018 International Conference on Manufacturing Technology, Materials and Chemical Engineering, MTMCE 2018

作者： Li, Hao Liu, Changliang School of Control and Computer Engineering North China Electric Power University Baoding Hebei071003 China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Changping District Beijing102206 China

As a kind of clean and renewable energy, wind energy is attracting more and more attention from all over the world. But the development of wind power is always hindered by the failure of downtime. The gearbox of wind power unit is one of the components with the highest failure rate in the whole wind turbine. Therefore, it is of great significance to study the fault diagnosis of gearbox in wind turbine. This paper first introduces the mathematical principle of wavelet analysis, and takes Matlab as an experimental platform to analyze and deal with the pitting fault data of a fan gearbox, and identifies the fault frequency by wavelet packet energy method, and diagnoses the type of failure. Finally, the experimental results are compared with other methods to deal with the data. Through the research in this paper, we can see that the data processing method based on wavelet analysis is simple and practical, especially in the engineering field represented by gearbox fault diagnosis. © Published under licence by IOP Publishing Ltd.

关键词： Wind power

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Losses Modeling Based on Domain Wall Processes and Valida-tion Considering Rotational Excitation of Electrical Steel Sheets.

Losses Modeling Based on Domain Wall Processes and Valida-ti...

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International Conference on Magnetics (INTERMAG)

On the basis of damping principle of vibration, the domain wall processes is investigated and modeled at low-to-medium frequencies in electrical steel sheets. Due to the energy dissipation chiefly descends from a micro-vortex current caused by domain wall motion, the coupled Landau-Lifshitz-Gilbert (LLG) and Maxwell electromagnetic diffusion equations are thus considered to describe the high-frequency characteristics. The overall core losses are eventually deduced in terms of separate contributions by domain wall processes and classical eddy current. Moreover, the calculation model can be extended to rotational excitation pattern. Hence, taking the typical electrical steel sheets as example, the novel core losses calculation model is analysed and compared with the total alternating core losses supplied by electrical steel sheets manufacturers and the 3-D rotating experimental core losses of sheets specimens which are carried out by using a 3-D magnetic properties testing system.

关键词： Magnetics Conferences

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A Novel Structure Design of Iron Core for power Transformers Considering Joints Forms and Magnetostriction.

A Novel Structure Design of Iron Core for Power Transformers...

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International Conference on Magnetics (INTERMAG)

作者： J. Li S. Wang H. Gao M. Liu J. Hong State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China State Key Laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of Technology Tianjin China

Body: power transformers and reactors are important devices in power transmission systems. But their cores and windings could produce vibration and acoustic noise by magnetostrictive effect, Maxwell electromagnetic stress and Lorentz force. Noise has become a bad environmental pollution source in some situations, and its vibration and noise reduction has become an urgent problem need to be solved. The shapes, materials, magnetostriction and joints forms of iron cores, the limitations of test, modeling, and experimental measurement of vibration and noise characteristic, are all the difficult reasons to analyze the vibration and acoustic noise of transformers and reactors. 1. The magnetostrictive modeling can be divided into two steps based on the magnetic field force and materials deformation, so the magnetic field force will be fed into the structural finite element with Maxwell electromagnetic force produced on the interface between the iron core and the air to calculate the deformation of the magnetic materials and to make the model more general and consistent. In order to fully verify the correctness of the model in the magnetostrictive analysis, and to ensure the simplicity of test and avoid unnecessary interference factors, the most simple magnetostriction tests will be carried out by using a single closed circle or rectangular electrical steel sheet, as shown in Fig. 1(a). The tests will measure the relationship between magnetostriction and magnetic field of different magnetic materials, different saturations, different sizes and different shapes. 2. The joint is a necessary form for the stacking of large transformer iron cores, and the main joint form is the step jiont at present. The introduction of the joints causes the magnetic force lines to flow through the different laminations and to make the local magnetic field complicated. From simple to complex process is adopted in this paper, and the verification is gradually complicated. Based on the study of a

关键词： Magnetics Conferences

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Effect of Vinyl Content on Mechanical Property and Electrical Tree Initiation in Silicone Rubber 2

Effect of Vinyl Content on Mechanical Property and Electrica...

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2nd IEEE International Electrical and Energy Conference, CIEEC 2018

作者： Sui, Jiangyuan Zhang, Ling Zhou, Yuanxiang Zhang, Xinyan Cheng, Zixia Guo, Shaowei School of Electrical Engineering Xinjiang University Urumqi830047 China State Key Lab of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing100084 China State Key Lab of Electrical Insulation and Power Equipment Xi'an Jiaotong University Xi'an710049 China School of Electrical Engineering Zhengzhou University Zhengzhou450001 China Electric Power Research Institute State Grid Jibei Electric Power Company Beijing100045 China

ISBN: (纸本)9781538653913

The vinyl content in methyl vinyl silicone oil has a significant impact on the mechanical and electrical properties of reinforced silicone rubber. In this study, mechanical property and electrical tree initiation of silicone rubber were studied by comparing different vinyl contents. The results show that shore hardness, tensile strength, elongation at break, and tear strength of insulating silicone rubber material increase first and then decrease with the of vinyl content increasing from 1% to 5%. The breakdown strength and the initiation voltage of electrical tree are basically consistent with the variation of tensile strength and tear strength. Detailed discussion are presented. This work could provide data support for the practical preparation of engineering silicone rubber. © 2018 IEEE.

关键词： Tensile strength

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TransMut: a program to predict HLA-I peptide binding and optimize mutated peptides for vaccine design by the Transformer-derived self-attention model

Research Square

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Research Square 2021年

作者： Chu, Yanyi Zhang, Yan Wang, Qiankun Zhang, Lingfeng Wang, Xuhong Wang, Yanjing Wang, Jianmin Jiang, Xue Salahub, Dennis Russell Xiong, Yi Wei, Dong-Qing State Key Laboratory of Microbial Metabolism Shanghai-Islamabad-Belgrade Joint Innovation Center on Antibacterial Resistances Joint International Research Laboratory of Metabolic & Developmental Sciences School of Life Sciences and Biotechnology Shanghai Jiao Tong University Shanghai200030 China Department of Chemistry CMS - Centre for Molecular Simulation IQST - Institute for Quantum Science and Technology University of Calgary 2500 University Drive NW CalgaryABT2N 1N4 Canada Department of Clinical Oncology The University of Hong Kong-Shenzhen Hospital Shenzhen China School of Electrical Engineering and Computer Science University of Ottawa 75 Laurier Ave. OttawaONK1N 6N5 Canada The Ministry of Education Key Laboratory of System control and information processing Department of Automation School of Electronic Information and Electrical Engineering Shanghai Jiao Tong University Shanghai200030 China Integrative Biotechnology & Translational Medicine Yonsei University Incheon21983 Korea Republic of Peng Cheng Laboratory Vanke Cloud City Phase I Building 8 Xili Street Nanshan District Guangdong Shenzhen518055 China

Computational prediction of the interaction between human leukocyte antigen (HLA) and peptide (pHLA) can speed up epitope screening and vaccine design. Here, we develop the TransMut framework composed of TransPHLA for pHLA binding prediction and AOMP for mutated peptide optimization, which can be generalized to any binding and mutation task of biomolecules. Firstly, TransPHLA is developed by using a Transformer-derived self-attention model to predict pHLA binding, which is significantly superior to 11 previous methods on pHLA binding prediction, neoantigen and human papilloma virus vaccine identification. For vaccine design, the AOMP program is then developed to automatically optimize mutated peptides to search for mutant peptides with higher affinity to the target HLA and with high homology to the source peptide. Among 3660 non-binding pHLAs, 3630 were successfully mutated. Of these, 94% were verified by the IEDB recommended method, and 88% have homology higher than 80% to the source peptide. © 2021, CC BY.

关键词： Peptides

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An AGC dynamic control method based on DQN algorithm

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IOP Conference Series: Materials Science and Engineering 2020年第1期729卷

作者： Su Jianjun Ma Changhui Li Shan Li Xiaoyu Zhang Bing Liu Wenxue State Grid Shandong Electric Power Research Institute Jinan 250003 China Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education (Shandong University) Jinan China State Grid Shandong Electric Power Company Jinan 250001 China

In order to cope with the incompatibility of traditional AGC control under CPS control performance standard, this paper proposes a hierarchical control framework based on DQN algorithm. It effectively solves the problem of dimensionality disaster of Q learning by using neural network instead of state action pair, and speed up the convergence. Through simulation verification, this method can effectively improve the system CPS control performance index and effectively reduce the system power generation cost.

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