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18th International Conference on AC and DC power Transmission, ACDC 2022

作者： Guo, Peiqian Yuan, Zhichang Han, Xuejiao Wu, Aijun Wang, Yuxuan Jiang, Zhilin State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China Energy Internet Research Institute Tsinghua University Beijing China

ISBN: (数字)9781839537615

ISBN: (纸本)9781839537615

The spread of the power electronics, both for control and power applications, in the realization of apparatuses the DC transformation in building distribution and utilization system. Currently, the research and discussion of the operation scheme and control strategy for low voltage photovoltaic-energy storage DC building system, LVPESDCBS, are relatively less. Focusing on these, in-depth research and analysis for control and operation scheme are conducted, and the related application possibility for different types LVPESDCBSs is discussed in this paper. At the start, the existing operational control strategies for the DC system are summarized. Following this, the centralized operational control scheme, which applies to the existing buildings that need to be renovated to DC type, and the decentralized operational control scheme for newly built DC buildings are studied respectively. Taking these conclusions into consideration, a ±375V LVPESDCBS digital model with various types of AC/DC power electronic devices is established in PSCAD/EMTDC. The proposed control strategy and operational scheme are verified through normal operation and single-pole operation of this LVPESDCBS. Finally, extended marketability requirement discussions of future DC building based on three perspectives: data drives, converter devices, and the application of DC technology are presented. © ACDC 2022. All rights reserved.

关键词： Digital storage

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Planning of a Single Flow Channel in Valve Blocks Based on Additive Manufacturing and the Ant Colony Algorithm

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Chinese Journal of Mechanical Engineering 2024年第5期37卷 191-202页

作者： Jin Zhang Ziyang Li Yuying Zhang Yandong Liu Ying Li Xiangdong Kong School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004China Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Qinhuangdao 066004China National&Local Joint Engineering Research Center for Advanced Manufacturing Technology and Equipment Qinhuangdao 066004China State Key Laboratory of Fluid Power and Mechatronic Systems Hangzhou 310027China

As electro-hydrostatic actuator(EHA)technology advances towards lightweight and integration,the demand for enhanced internal flow pathways in hydraulic valve blocks ***,owing to the constraints imposed by traditional manufacturing processes,conventional hydraulic integrated valve blocks fail to satisfy the demands of a more compact channel layout and lower energy ***,the subjectivity in the arrangement of internal passages results in a time-consuming and labor-intensive *** study employed additive manufacturing technology and the ant colony algorithm and B-spline curves for the meticulous design of internal passages within an aviation EHA valve *** layout environment for the valve block passages was established,and path optimization was achieved using the ant colony algorithm,complemented by smoothing using B-spline ***-dimensional modeling was performed using SolidWorks software,revealing a 10.03%reduction in volume for the optimized passages compared with the original *** fluid dynamics(CFD)simulations were performed using Fluent software,demonstrating that the algorithmically optimized passages effectively prevented the occurrence of vortices at right-angled locations,exhibited superior flow characteristics,and concurrently reduced pressure losses by 34.09%-36.36%.The small discrepancy between the experimental and simulation results validated the efficacy of the ant colony algorithm and B-spline curves in optimizing the passage design,offering a viable solution for channel design in additive manufacturing.

关键词： Hydraulic valve block Flow channel B-spline curve Additive manufacturing Ant colony algorithm

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Transient Behaviors of Space Charge in Low-density Polyethylene Films at Prebreakdown Under Temperature Fields

Transient Behaviors of Space Charge in Low-density Polyethyl...

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中国物理学会第二十二届全国静电学术年会

作者： Ling Zhang Zekai Lu Yuanxiang Zhou Zhaowei Peng Zixia Cheng Yonggang Guan State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department School of Electrical Engineering Zhengzhou UniversityZhengzhou 450001China

Currently,insulation performance of high voltage DC(HVDC)power cables is still of critical significance challenge in both engineering application and fundamental *** example,HVDC cable insulation suffers breakdown under the conditions of cold start and load cycling tests,and the presence of space charge at high temperatures causes electric field distortion within the ***,the operating temperature of HVDC cables could only reach 70℃at *** work intends to carry out research on the effect of temperature on space charge characteristics of low-density polyethylene(LDPE)films at prebreakdown under a linearly ramping voltage,which is of great significance for further understanding and improving the operating temperature and breakdown strength of HVDC ***-free LDPE film with a thickness of 100 μm was purchased from GoodFellow *** improved space charge measurement system was developed with a high-speed measurement interval of 1 ms,a high voltage pulse of 120 V,and a pulse width of 5 ns.A linearly ramping voltage of 0.5 kV/s was selected and cut off after breakdown *** and steady behaviors of space charge was comprehensively sudied under a linearly ramping voltage of 500 V/s at 30℃and 70℃,*** results show that negative charge was rapidly injected and accumulated near the anode at a relatively low electric field at 70℃.As the applied electric field gradually increased,the anode appeared a significant positive charge *** phenomenon occurred when charge packets were injected to a certain distance of~30 μ*** the contrast,there was only negative charge injection and accumulation in the bulk of LDPE films at 30℃,and breakdown was not observed even when the voltage rose to-30 *** was found that the anode had a positive space charge packet injection at 30℃and slowly migrated to the cathode,and the entire transit process took tens of *** the internal electric field distribution,the ma

关键词： LDPE prebreakdown transient space charge internal field distortion carrier mobility

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Charge Evolution and Dielectric Property of Three-phase Polypropylene Composites With Enhanced Mechanical Performance

Charge Evolution and Dielectric Property of Three-phase Poly...

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中国物理学会第二十二届全国静电学术年会

作者： Ling Zhang Zhaowei Peng Yuanxiang Zhou Zekai Lu Yonggang Guan Zixia Cheng State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department School of Electrical Engineering Zhengzhou UniversityZhengzhou 450001China

High voltage DC(HVDC)power cable technology has the advantages of large transmission capacity,low loss,negligible electromagnetic environmental effect,and trackless corridor,etc.,which make it capable to solve the significant problem of power transmission channels during the fast development of electric ***,it also contributes to eco-friendly,resource-saving,safe,and reliable goal of power transmission *** to common crosslinked polyethylene materials,isotactic polypropylene(iPP)has the advantages of non-crosslinking,high-temperature-resistant,recyclable,low production cost,and free maintenance work,and has been a hot spot in the research field of high performance HVDC cable insulating ***,iPP is a thermoplastic limited by its impact strength,especially at low temperatures,because of its high degree of crystallinity and high glass transition *** of the common methods used to increase the impact strength is the addition of low-molecular elastomer materials or nucleating agents(NAs)into the iPP matrix,which is blended with the polymer in the molten *** previous investigations with the binary blending system have demonstrated that improved impact resistance usually was accompanied by decreasing the stiffness or deteriorating its original electrical properties in some *** order to achieve an optimum balance of macroscopic properties,adding several components is often necessary in polymer *** aim of this work is to investigate the synergistic effects on mechanical and electrical properties between NAs and different elastomers in iPP *** have shown that increasing the β-crystal content can improve its electrical property and elastomer can strengthen its mechanical performance.,Thus,three-phase iPP blends(iPP-β-x,x refers to the elastomer)were prepared with the incorporation of arylamide derivative β-NAs(TMB-5,0.2 wt%)and different elastomers(15 wt%)including styrene-bethylene butylene-b-styr

关键词： isotactic polypropylene β nucleating agent elastomer impact strength space charge

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Movement simulation of long electric arc along the surface of insulator string in free air

Movement simulation of long electric arc along the surface o...

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作者： Gu, Shanqiang He, Jinliang Zhang, Bo Xu, Guozheng Han, Shejiao State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

This paper presents the study of a long electric arc in free air due to lightning stroke on the parallel gap lightning protection device (PGLPD) on high-voltage overhead transmission lines. Based on the latest electric arc model, the analysis method of the magnetic field generated by the current flowing through the PGLPD, electric arc, transmission lines, steel tower, and ground wires is developed, and the movement process of the long arc along the surface of the insulator strings is simulated. The simulation results are in agreement with the experimental results. The study is very helpful for the optimal design and suitable assemblage of the PGLPD. © 2006 IEEE.

关键词： Electric arcs

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Steady-state model of multi-port electric energy router and power flow analysis method of AC/DC hybrid system considering control strategies

Steady-state model of multi-port electric energy router and ...

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作者： Shen, Yu Zhu, Fengju Zhang, Chunpeng Cai, Weiqian Yuan, Liqiang Li, Kai Zhao, Zhengming State Key Lab of Control and Simulation Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

This study proposes a steady-state model of multi-port electric energy router (EER) and a power flow analysis method for AC/DC hybrid system considering control strategies. Firstly, a circuit topology model of EER is put forward, including AC and DC port equivalent parts. Secondly, considering external control characteristics of EER, the control strategies including PQ mode, V/f mode, and droop mode are established, which is suitable for system analysis. Then, using the extended sub-network model, an AC/DC power flow model containing multi-port EER is established. In terms of the power flow algorithm for AC/DC hybrid system, AC/DC network admittance matrix and the extended AC/DC network modification equations are applied to solve the problem. Two examples are designed and show that EER can be used for flexible power regulation and voltage improvement. Besides, power flow analysis method of AC/DC hybrid system is demonstrated to be effective. © 2019 Institution of Engineering and *** right reserved.

关键词： Topology

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Research on Multi-Level Collaborative Scheduling Model Based on Distributed power Connected to the New power System 4

Research on Multi-Level Collaborative Scheduling Model Based...

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4th IEEE International Conference on power, Electronics and Computer Applications, ICPECA 2024

作者： Zhou, Ji Yang, Zijun Li, Kai Xia, Lei Tan, Huilei Xu, Lina State Grid Corporation of China Beijing China State Grid Jiangsu Electric Power Co. Ltd Jiangsu Province Nanjing China Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Beijing China

ISBN: (纸本)9798350359589

After the distributed power supply connects to the new power system, the power grid scheduling is affected by voltage flash during the grid scheduling, resulting in an increase in operating costs of the power grid. It is proposed that the high -penetration distribution power supply connects the diversified electric energy dual -layer scheduling method of the new power system. After mastering the current adjustment of the load and credible contribution information of the power grid, this paper builds a multi -purpose power system diversified power dual-layer scheduling model based on multi -target optimization. The upper layer scheduling target of this model is to optimize the quality of diversified electricity. The lower layer scheduling goal is to maximize the economic benefits of the new power system. The minimum value method can be solved to achieve the upper and lower target functions. The system schedules the optimal solution to ensure that under the access to high penetration distributed power supply, to ensure the maximization goal of the economic benefits of the power grid, it reasonably dispatches the displacement of the distributed power supply, and realizes the optimization of the diversified power quality of the new power system. The experimental results show that under the scheduling of this method, the voltage offset of the photovoltaic grid system is reduced by 0.60 MV. The operating cost of the new power system is also effectively controlled. Compared with that before the scheduling, this method is available. © 2024 IEEE.

关键词： distributed power multi-layer collaboration new power system optimal scheduling

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Fast monte carlo simulation of dynamic power systems under continuous random disturbances

Fast monte carlo simulation of dynamic power systems under c...

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2020 IEEE power and Energy Society General Meeting, PESGM 2020

作者： Qiu, Yiwei Lin, Jin Chen, Xiaoshuang Liu, Feng Songy, Yonghua Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Beijing100084 China The University of Macau Department of Electrical and Computer Engineering 999078 China

ISBN: (纸本)9781728155081

Continuous-time random disturbances from the renewable generation pose a significant impact on power system dynamic behavior. In evaluating this impact, the disturbances must be considered as continuous-time random processes instead of random variables that do not vary with time to ensure accuracy. Monte Carlo simulation (MCs) is a nonintrusive method to evaluate such impact that can be performed on commercial power system simulation software and is easy for power utilities to use, but is computationally cumbersome. Fast samplings methods such as Latin hypercube sampling (LHS) have been introduced to speed up sampling random variables, but yet cannot be applied to sample continuous disturbances. To overcome this limitation, this paper proposes a fast MCs method that enables the LHS to speed up sampling continuous disturbances, which is based on the Itô process model of the disturbances and the approximation of the Itô process by functions of independent normal random variables. A case study of the IEEE 39-Bus System shows that the proposed method is 47.6 and 6.7 times faster to converge compared to the traditional MCs in evaluating the expectation and variance of the system dynamic response. © 2020 IEEE.

关键词： Random processes

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Adaptive Time Period Aggregation for Day-ahead Unit Commitment

Adaptive Time Period Aggregation for Day-ahead Unit Commitme...

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2022 Tsinghua-IET Electrical Engineering Academic Forum, TDF 2022

作者： Yu, Zekuan Zhong, Haiwang Yan, Xinfei Department of Electrical Engineering Tsinghua University Beijing China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Beijing China

ISBN: (数字)9781839537998

ISBN: (纸本)9781839537998

The growing penetration of renewables calls for finer temporal resolutions of the day-ahead unit commitment (DA-UC) problem in order to accommodate the fluctuations and improve the performance of UC schedules, leading to the expansion of the DA-UC problem scale. However, due to its high computational burden, the viability of adopting larger UC models in practice becomes a challenge. In this paper, an adaptive time period aggregation strategy and a corresponding DA-UC model are proposed to reduce the model scale while preserving feasibility and accuracy. The aggregation strategy integrates the statistical characteristics of net demand with the operational characteristics of thermal units to effectively capture the consistency in on/off statuses. Case study based on the IEEE 118-bus system validates that, combined with a post-processing procedure, the proposed strategy and model can provide near-optimal UC schedules with approximately 5 times acceleration for various demand profiles, enhancing computational efficiency. © 2022 IET Conference Proceedings. All rights reserved.

关键词： Computational efficiency

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The Optimal Design of the Second-Order Generalized Integrator Phase-Locked Loop Under power Voltage Distortion Conditions 5

The Optimal Design of the Second-Order Generalized Integrato...

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5th IEEE Conference on Energy Internet and Energy System Integration, EI2 2021

作者： Zhang, Xin Gong, Lijiao Wang, Bin Si, Jindong College of Mechanical and Electrical Engineering Shihezi University Shihezi China Shihezi China State Key Laboratory of Safety Control and Simulation of Power Systems and Power Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781665434256

Phase-locked loop (PLL) based on traditional second-order generalized integrator (SOGI) cannot obtain the voltage, frequency and phase information accurately when there are multiple harmonic interference and DC offset in grid voltage. To solve this problem, this paper proposes an improved PLL that can suppress harmonic and eliminate DC component to extract the synchronous signal accurately. First of all, based on the derivation of distorted grid voltage expression, the problem offluctuation in extracting synchronous signal from three-phase unbalanced voltage with harmonic by traditional PLL is analyzed. Then, the design of improved PLL is proposed, which is composed of an improved second-order generalized integrator and a frequency correction component which can suppress harmonics and eliminate disturbances under the condition of grid voltage distortion, and has self-adaptability in large frequency offset. Determine the control parameters to ensure that the proposed PLL structure has a better rejection to harmonic distortion than previous approaches, and realize accurate tracking of grid fundamental frequency synchronization information. Finally, the behavior of the proposed system is verified with MATLAB/Simulink simulation and Hardware-in-Loop Experimental Platform which prove the proposed PLL can realize the synchronous tracking performance of grid frequency and phase quickly and accurately in the non-ideal grid environment, and the results are consistent with the theoretical analysis. © 2021 IEEE

关键词： Phase locked loops

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