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Analysis on Differential protection Sensitivity of Traction Transformers Based on Different Conversion Modes

IOP Conference Series: Earth and Environmental Science 2020年第1期617卷

作者： Liu Xiaobao Zheng Yuping Long feng Wu Tonghua Pan Shuyan An Lin State Key Laboratory of Smart Grid Protection and Control Nari Group Corporation Nanjing Jiangsu 211106 China

With the rapid development of high-speed rail technology in China, the traction transformers of various types have been used more and more extensively. The differential protection of traction transformers has different differential conversion modes [1-2] which are different in their sensitivities. In this paper, taking the YNV traction transformer as an example, by comparing the sensitivities of two different common differential conversion modes and through analysis, it shows that the sensitivities of differential protection are slightly different. The sensitivities of differential protections based on different principles depend on the retention degree of differential current to the positive sequence, negative sequence and zero sequence components in the internal fault current. The sensitivity of phase current minus zero sequence differential is the highest when single-phase grounded, which completely retains all the sequence components in the internal fault current. The sensitivity of interphase differential protection is the highest when interphase fault occurs. The widely used phase current differential and phase current minus zero sequence differential do not reflect the zero-sequence component of internal fault current, which provides the basis for field fault analysis and setting.

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LCC-HVDC supplementary controller design based on global fast terminal sliding mode control 2

LCC-HVDC supplementary controller design based on global fas...

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2nd IEEE International Conference on Energy Internet, ICEI 2018

作者： Liu, Qipu Sun, Guoqiang Nong, Weizhi Lin, Zijie Tang, Xiaochen Yang, Jia College of Energy and Electrical Engineering Hohai University Nanjing China State Key Laboratory of Smart Grid Protection and Control NARI Group Corporation Nanjing China

ISBN: (纸本)9781538641316

Conventional LCC-HVDC is a non-linear, tightly coupled system. Since the performance of PI control varies from different operation conditions, the optimal of parameter tuning is only achieved under steady state. To improve dynamic performance and stability of system, A novel HVDC nonlinear supplementary controller based on Terminal sliding mode theorem has been proposed. First, the steady state mathematical model of the LCC-HVDC system is built, the approach of state feedback exact linearization is adopted to change the nonlinear model into a linear one, the decoupled relationship between the control variables are investigated;then based on sliding mode control method, the constant current and constant voltage control in rectifier and inverter has been achieved, respectively. The variables converge to equilibrium point fast and exactly. Finally, the strategy is demonstrated through Matlab/Simulink software, the simulation results show that the controller is capable of tracing the reference, and the robustness with respect to parameters' perturbations is satisfied. The controller contributes significantly toward improving transient performance comparing to conventional PI control and restraining commutation failure. © 2018 IEEE.

关键词： controllers

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Status evaluation of smart substation measurement and control device

Status evaluation of smart substation measurement and contro...

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第二届先进电子材料、计算机与材料工程国际学术会议（AEMCME 2019）

作者： Zhang Min Shen Jian Chen Li Zhou Bin Zhou Shao Liang Hou Zhe NARI Group Corporation (State Grid Electric Power Research Institute) State Key Laboratory of Smart Grid Protection and Control NARI Technology Corporation Co. Ltd

In power system, measurement and control device plays an important role in maintaining an ideal level of reliability. Therefore, the reliability of the measurement and control device should be evaluated to fully understand the cause of its failure. A new evaluation model is proposed, which relates the fault of measurement and control system with the four main reasons of device hardware fault, software fault, auxiliary equipment fault and human fault. In addition, the model can also comprehensively consider other aspects of the measurement and control system, such as human error in testing and software upgrade, effectiveness of daily operation monitoring, degree of dependence on self-inspection, local backup and misoperation. These studies have a lot of significance to the reliability of the control system, and also can effectively improve the stability of the system.

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A hybrid model based on convolutional neural network and long short-term memory for short-term load forecasting

A hybrid model based on convolutional neural network and lon...

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IEEE Power and Energy Society General Meeting

作者： Jixiang LU Zhihong YANG Qipei ZHANG Mengfu TU Technology Research Center NARI Group Corporation Nanjing China State Key Laboratory of Intelligent Power Grid Protection and Operation Control Nanjing China

To better mine the effective information contained in massive data and improve the accuracy of short-term load forecasting, this paper proposes a hybrid model based on convolutional neural network and long short-term memory network (CNN-LSTM) for short-term load forecasting (STLF), which takes massive historical load data, meteorological data, date information, and peak-valley electric price data as input by constructing continuous feature maps with time sliding window. Convolutional neural network (CNN) is used to extract features and reshape them into vectors. The feature vectors are constructed in temporal and fed into long short-term memory network (LSTM) which is used to predict STLF. To the best of our knowledge, this is the first work to predict STLF using deep learning in both spatial and temporal domains. It is shown that the forecasting accuracy can be notably improved by CNN-LSTM hybrid model method. The effectiveness of the proposed method is validated through extensive comparison studies on a real-world dataset.

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A Measurement Method for Wide-frequency Harmonic Signal in Power grid Based on Window Interpolation FFT and RLS-Adaline Neural Network

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Journal of Physics: Conference Series 2021年第1期1920卷

作者： Jiawei Peng Shuguo Pan Wenxiu Wang Min Zhang Jian Shen Wang Gao Chenglin Xia School of Instrument Science and Engineering Southeast University Nanjing Jiangsu 210096 China School of Electronic and Information Engineering Jinling Institute of Technology Nanjing Jiangsu 211169 China Nari Technology Co. Ltd Nanjing Jiangsu 211106 China State Key Laboratory of Smart Grid Protection and Control Nanjing Jiangsu 211106 China

With the increase of non-linear loads in power grid and the development of power electronics, the growing serious harmonic pollution has put forward higher requirements for the accuracy and real-time performance of the measurement method. For this problem, this paper proposes a wide-frequency harmonic signal measurement method based on window interpolation FFT and adaptive neural network. After the window function is selected, the frequency of harmonic is estimated by double-spectrum-line interpolation algorithm based on three-term third derivative Nuttall window, and then the smoothed frequencies are input into RLS-Adaline neural network to estimate the amplitude and phase of each harmonic. The simulation results show that the proposed method has higher measurement accuracy and stability under few data conditions and low signal-to-noise ratios than conventional window interpolation algorithms. High accuracy measurement of harmonics with short time window in the range of 0∼2.5kHz is effectively realized.

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Workload-Aware Scheduling for Data Analytics upon Heterogeneous Storage

Workload-Aware Scheduling for Data Analytics upon Heterogene...

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IEEE International Conference on Big Data and Cloud Computing (BdCloud)

作者： Zhuzhong Qian Yuan Gao Mingtao Ji Hui Peng Peng Chen Yibo Jin Sanglu Lu State Key Laboratory for Novel Software Technology Nanjing University Nanjing China NARI Research Institute NARI Group Corporation(State Grid Electric Power Research Institute) Nanjing System R&D Center NARI Technology Co. Ltd. Nanjing State Key Laboratory of Smart Grid Protection and Control NARI Group Corporation Nanjing

ISBN: (数字)9781728143286

ISBN: (纸本)9781728143293

A trend in nowadays data centers is that equipped with SSD, HDD, etc., heterogeneous storage devices are widely deployed to meet diverse demands of various big data workloads. Since the reading performance of various storage devices are quite different, traditional concurrent data fetching easily incurs unbalanced use among devices. As a result, the straggler in terms of the data fetching, derived from the unbalanced use, directly increases the overall latency of data analytics. To avoid such unbalanced use on fetching large volume of data concurrently from storage devices, we formulate Workload-Aware Scheduling problem for Heterogeneous storage devices (WASH), the goal of which is to minimize the maximum data fetching time for parallel data analytical tasks. We design a randomized algorithm (rWASH) to select a proper source device for each task based on delicate calculated probabilities, which can be proved concentrated on its optimum with high probability. Extensive experiments show that rWASH reduces the average data fetching time for tasks by up to 55% over the state-of-the-art algorithms.

关键词： Task analysis Performance evaluation Data analysis Scheduling Data centers Probability Hardware

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Reliability analysis of security and stability control system with typical structure in power grids

Reliability analysis of security and stability control syste...

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IEEE General Meeting Power& Energy Society

作者： Xijian Dong Chanan Singh Heping Jia Bijun Li State Key Laboratory of Smart Grid Protection and Control NARI Group Corporation Nanjing China Texas A&M University College Station USA State Grid Economic and Technological Research Institute Co. LTD. Beijing China

The security and stability control system (SSCS) is the second line of defense for prevention of security breach and control of power systems in China. With the development of smart grid technologies, it has been becoming more complex with an increasing trend of reliability requirements. In this paper, a typical application of SSCS in the power grid and its optimized design for ensuring its correct action are introduced. The Markov process model is developed to evaluate the availability of the proposed SSCS. The concept and algorithm of integrity for the SSCS are proposed with the consideration of equipment availability and functional reliability. Combined with the conclusion of the integrity calculation, useful suggestions for the design of SSCS are provided.

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B2DASH: Bandwidth and buffer-based dynamic adaptive streaming over HTTP 3rd

B2DASH: Bandwidth and buffer-based dynamic adaptive streamin...

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3rd International Conference on Machine Learning and Intelligent Communications, MLICOM 2018

作者： Du, Peihan Wang, Jian Wang, Xin Xu, Zufeng Nanjing University Nanjing China 61428 unit of the Chinese People’s Liberation Army Beijing China State Key Laboratory of Smart Grid Protection and Control NARI Group Corporation 19 ChengxinRoad Nanjingjiangsu211000 China

ISBN: (纸本)9783030005566

Currently, video streaming technology is widely used for entertainment, advertising, social networking and so on. Dynamic adaptive streaming over HTTP (DASH) has largely replaced the previous release of streaming video using UDP. Many researchers have proposed algorithms to improve DASH performance. There are two types of methods: bandwidth-based and buffer-based. Both methods have pros and cons. In this article, we propose a DASH algorithm that takes both bandwidth and buffer into account. And we imitate the method of network congestion control to adjust bitrate of the video segment. The algorithm was implemented and tested, and compared with the state-of-the-art DASH algorithm–BOLA. The results showed that B2DASH outperformed BOLA for both the average bitrate and buffer rise time. © ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering 2018.

关键词： Adaptive algorithms

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Vertically integrated outdoor in-site line protection based on SoC technique

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Global Energy Interconnection 2018年第2期1卷 179-186页

作者： Tonghua Wu Yuping Zheng Yutao Qiu Xiaoping Zhang Gang Yao Jimin Chai Xiaofan Hou College of Energy and Electrical Engineering Hehai University NARI Group Corporation/State Grid Electric Power Research Institute State Key Laboratory of Smart Grid Protection and Control State Grid Zhejiang Electric Power Corporation Electrical and System Engineering University of Birmingham

By focusing on the problems of speed, reliability, operation and maintenance in the practical application of line protection in conventional and smart substations, we propose system architecture and a technical scheme for in-site(similar in meaning to on-site or near-process) line protection based on vertical integration and outdoor installation. The functions of the single-bay merging unit, relay protection, and intelligent terminal are vertically integrated to reduce the number and types of devices, simplify the configuration, reduce signal transmission, and shorten the protection action time. In addition, this vertically integrated device is applied to provide data acquisition and control execution support for substation-area protection, security and stability of devices, and other substation-area devices. The vital performance outputs are tested and compared. Finally, the experimental results verify that the proposed scheme is feasible and the technology is advanced.

关键词： Line protection In-site relay protection Merging unit Vertical integration

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Optimized Decision Making for Power grid Safety Correction Based on Sub-regional Load control

Optimized Decision Making for Power Grid Safety Correction B...

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IEEE Information Technology and Mechatronics Engineering Conference (ITOEC)

作者： Yi WANG Xin SHAN Guoqiang ZHA tate Key Laboratory of Smart Grid Protection and Control Nanjing China

ISBN: (纸本)9781538653746

In the case of large-scale power loss fault in the operation of UHV AC-DC hybrid power grid, it is impossible to adjust the grid correction control problem by the unit output adjustment. Fully utilize the adjustable capacity of the load control to achieve safety correction control to meet the load control aid decision-making requirements of existing dispatching system. According to the characteristics of the dispatching system in accordance with the sub-regional load as the target of unified implementation of load control, this paper proposes a safety correction optimized aid decision-making calculation method based on sub-regional load control, with the sub-regional load as the control object and the minimum sub-regional load as the target. Consider the system power flow constraint, the sub-regional controllable load constraint and the key monitoring section safety constraints, the continuous power flow method and the line planning method are combined to solve the problem. The proposed method has the characteristics of simple model, easy solution and good convergence. It shows the effectiveness of the proposed method in the actual power grid. 1

关键词： Power grids Load flow Load flow control Load modeling Sensitivity Optimization Safety

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