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Analysis of electrical tree ageing in silicone rubber by physicochemical approach

Journal of Physics: Conference Series 2009年第1期183卷

作者： Y X Zhou Q Nie Z Z Chen R Liu State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China Department of Electrical Engineering Zhengzhou University Zhengzhou 450001 China

In this paper, the characteristics of electrical tree ageing in silicone rubber (SIR) under AC voltage were studied. The electrical tree initiation rate is 20% after the application of 6 kV AC voltage for 1000 hours. Samples are separated into three kinds according to processes of electrical tree formation: virgin samples without voltage application, non-treed samples without electrical tree formation after 1000 hours and treed samples with electrical tree formation after 1000 hours. Certain physicochemical diagnostic tests were carried out to understand the degradation of material, ascribed to long-time voltage application, using differential scanning calorimetry (DSC) and thermogravimetric-differential thermal analysis (TG-DTA). Physicochemical analyses, especially the DSC results, show that no additional phases are formed in the processes of electrical tree ageing in SIR. Reduction of the melting point and crystallinity of SIR is observed in the sequence of virgin samples, non-treed samples and treed samples. The activation energy values were calculated from the TG-DTA data. Compared to virgin samples, obvious reduction of activation energy value is observed in non-treed samples. Degradation in SIR has already occurred before electrical tree formation and charge injection and extraction by high field electrode under AC voltage is regarded as the reason.

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Test and Analysis of Conducted Disturbance Sources of the Truck Crane under Stable Conditions

Test and Analysis of Conducted Disturbance Sources of the Tr...

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International Symposium on Electromagnetic Compatibility

作者： Li Xiao Zhanqing Yu Shuiming Chen Bo Zhang Rong Zeng Chijie Zhuang Yang Zeng Xiaoying Yu Qian Zhang State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Research Institute Zoomlion Heavy Industry Science & Technology Development Co. Ltd.

ISBN: (纸本)9781467307185

The Electromagnetic Compatibility (EMC) is a major issue for the truck crane designing, due to the large dimension. The conducted disturbance sources of truck crane was measured under stable conditions, the time domain characteristics of possible conducted disturbance sources was analyzed, and typical waveforms were concluded to solve the EMC (Electromagnetic Compatibility) issue. The electromagnetic disturbance characteristics at different test points under different operation conditions were compared, and the influence of different factors was studied. The amplitude and frequency parameters of the major disturbance sources were compared with the standard immunity test pulses suggested by ISO7637-2. The differences between them indicate that the extant standard might not apply to the test of the truck crane. The presented results could form a basis for the development of a special standard for the EMC test of the truck crane and further relevant EMC research.

关键词： Truck crane EMC Conducted disturbance source Time domain characteristics Electromagnetic immunity test

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Design of a flexure-based XY positioning stage with balanced axial forces on decoupling modules

Design of a flexure-based XY positioning stage with balanced...

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International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO)

作者： Zhen Zhang Zhiqing Liu Peng Yan Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control Tsinghua University Beijing China State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang University Hangzhou China Department of Mechanical Engineering Beijing China School of Automation Science and Electrical Engineering Beihang University Beijing China School of Mechanical Engineering Shandong University Jinan China

ISBN: (纸本)9781509029464

This paper presents a novel beam flexure-based XY positioning stage with an axial force balanced design of double parallelogram decoupling modules. By mean of connecting two decoupling modules along the same actuation axis, the axial forces are evenly applied to each side of the motion stage. Therefore the in-plane rotation can be significantly restricted. Also a redundant constraint is proposed to the guidance module to restrict its rotational motions. The monolithical fabrication of the spatial configuration of the proposed mechanism can be resorted to additive manufactured technology. Numerical simulation results validate the effectiveness of the proposed XY positioning stage.

关键词： Force Actuators Joining processes Numerical simulation Nanopositioning Kinematics Stress

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印度大停电与继电保护的三大功能

印度大停电与继电保护的三大功能

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2012年中国智能电网学术研讨会

作者： DONG Xin-zhou 董新洲 CAO Run-bin 曹润彬 WANG Bin 王宾 SHI Shen-xing 施慎行 Dominik Bak State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua Universi 清华大学电力系统及发电设备安全控制和仿真国家重点实验室北京 100084

简介了印度电网在2012年7月30日和7月31日发生的两起大停电事故。两起事故均起源于同一回输电线路距离保护Ⅲ段因过负荷保护动作跳闸，并导致其他设备继电保护的不合理动作而引发连锁跳闸，造成大面积停电。印度大停电事故暴露了现有电... 详细信息

简介了印度电网在2012年7月30日和7月31日发生的两起大停电事故。两起事故均起源于同一回输电线路距离保护Ⅲ段因过负荷保护动作跳闸，并导致其他设备继电保护的不合理动作而引发连锁跳闸，造成大面积停电。印度大停电事故暴露了现有电力系统的脆弱性，尤其是继电保护在过负荷和系统振荡情况下的动作缺陷。基于对停电事故中继电保护行为的分析，提出了满足现代电网需求的继电保护三大功能：面向系统安全的系统保护功能、预防性保护功能和快速切除故障设备功能。

关键词：停电事故继电保护过负荷故障处理

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Optimal power and energy sizing of compressed air energy storage in distribution network using multiparametric programming

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IOP Conference Series: Earth and Environmental Science 2021年第1期675卷

作者： Fan Chen Zhongjie Guo Qiyou Lin Xiaodai Xue Yuguang Xie Shengwei Mei State Grid Anhui Electric Power Research Institute Hefei 230601 China State Key Lab of Control and Simulation of Power Systems and Generation Equipments (Dept. of Electrical Engineering Tsinghua University) Haidian District Beijing 100084 China State Grid Wuhu Electric Power Supply Company Wuhu 241027 China

As a new type of mechanical energy storage, compressed air energy storage (CAES) has attracted wide attention in recent years. This paper studies the optimal sizing problem of CAES in power distribution network (PDN). CAES plays a role in shaving the peak and filling the valley at demand side and thus reduces the operation cost of PDN to purchase electricity from the main grid. A multi-parametric linear programming (MP-LP) model is formulated where the power and energy capacities of CAES are regarded as parameters; the parameterized optimal value function (OVF) provides a graphical tool to describe the impact on operation cost of CAES configuration, which helps determine the planning strategy in a visual manner. The visualized results reveal not only the optimal solution, but also some useful information, like the sensitivity of operation cost to parameters. Case studies conducted on the IEEE 33-bus distribution system verifies the effectiveness of the proposed method.

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A multi-source data collection and information fusion method for distribution network based on IOT protocol

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IOP Conference Series: Earth and Environmental Science 2021年第2期651卷

作者： Yongxiang Cai Xiaobing Xiao Hao Tian Yu Fu Peng Wu Hongliu He Electric Power Research Institute of Guizhou Power Grid Co. Ltd. Guiyang China State Key Lab of Control and Simulation of Power Systems and Generation Equipments (Dept. of Electrical Engineering Tsinghua University) Beijing China Binjiang College of Nanjing University of Information Science and Technology Wuxi China

With the construction of Global Energy Internet, Intelligent distribution network has more and more characteristics of multi scene, multi service and changeable measurement and control objects. In order to realize data collection and information exchange among the intelligent terminal and energy, power grid, load, energy storage and other control resources in distribution network, we should research an architecture which can adapt to various data sources Based on dynamic self describing protocol.

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Open Architecture Design of Universal Terminal for Multiple Measurement and control Scenarios of Distribution Network

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IOP Conference Series: Earth and Environmental Science 2021年第2期651卷

作者： Ruifeng Zhang Xiaobing Xiao Hao Tian Yongxiang Cai Yu Fu Hongliu He Electric Power Research Institute of Guizhou Power Grid Co. Ltd. Guiyang China State Key Lab of Control and Simulation of Power Systems and Generation Equipments (Dept. of Electrical Engineering Tsinghua University) Beijing China Binjiang College of Nanjing University of Information Science and Technology Wuxi China

Introduce the IoT platform technology based on SDN (Software Defined Network), cloud-based, flexible management and configuration of smart terminals, and support access to millions of terminal devices and smart operation and maintenance management. The traditional monitoring system is integrated with the Internet of Things platform, and on the basis of realizing the general SCADA system monitoring function, through the side-cloud collaboration, the lean management of the distribution station area is realized.

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Design of the PID temperature controller for an alkaline electrolysis system with time delays

arXiv

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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

Electrolysis systems use proportional-integral-derivative (PID) temperature controllers to maintain stack temperatures around set points. However, heat transfer delays in electrolysis systems cause manual tuning of PID temperature controllers to be time-consuming, and temperature oscillations often occur. This paper focuses on the design of the PID temperature controller for an alkaline electrolysis system to achieve fast and stable temperature control. A thermal dynamic model of an electrolysis system is established in the frequency-domain for controller designs. Based on this model, the temperature stability is analysed by the root distribution, and the PID parameters are optimized considering both the temperature overshoot and the settling time. The performance of the optimal PID controllers is verified through experiments. Furthermore, the simulation results show that the before-stack temperature should be used as the feedback variable for small lab-scale systems to suppress stack temperature fluctuations, and the after-stack temperature should be used for larger systems to improve the economy. This study is helpful in ensuring the temperature stability and control of electrolysis systems. Copyright © 2022, The Authors. All rights reserved.

关键词： Three term control systems

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Thermal Modelling and controller Design of an Alkaline Electrolysis System under Dynamic Operating Conditions

arXiv

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arXiv 2022年

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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Measurement-driven AA-CAES Model for Distribution Network Dispatch in Coordination with Renewable generation

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IOP Conference Series: Earth and Environmental Science 2020年第1期529卷

作者： Yuguang Xie Jiayu Bai Dangwu Liu Tianwen Zheng Shengwei Mei State Grid Anhui Electric Power Research Institute Hefei 230601 China State Key Lab of Control and Simulation of Power Systems and Generation Equipments (Dept. of Electrical Engineering) Tsinghua University Beijing 100084 China State Grid Anhui Electric Power CO. LTD. Hefei 230022 China Sichuan Energy Internet Research Institute Tsinghua University Chengdu 610213 China

Advanced adiabatic compressed air energy storage (AA-CAES) could play an important role in power distribution system for mitigating the intermittency of distributed renewable generations and reducing the peak-valley difference of load demand, which requires to operate AA-CAES under off-design conditions. A power system dispatch oriented AA-CAES model was proposed based on the technically thermodynamic performance curves of compressor and expansion calibrated from experiments, highlighting the impact of AA-CAES part-lard features on charging/discharging efficiency and capacity. The proposed model is integrated with economic dispatch problem of power distribution systems, giving rise to a nonlinear program due to the state-dependent charging and discharging performances. The dispatch model is further linearized via piecewise linear approximation and special-ordered set of type 2, and its equivalent mixed integer linear formulation is presented. A modified IEEE 33-bus system is adopted to verify the effectiveness of proposed model for renewables accommodation.

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