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Learning the continuous-time optimal decision law from discrete-time rewards

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National Science Open 2024年第5期3卷 130-147页

作者： Ci Chen Lihua Xie Kan Xie Frank Leroy Lewis yilu liu Shengli Xie School of Automation Guangdong University of TechnologyGuangdong Key Laboratory of IoT Information TechnologyGuangzhou 510006China Key Laboratory of Intelligent Information Processing and System Integration of IoT Ministry of EducationGuangzhou 510006China School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore 639798Singapore 111 Center for Intelligent Batch Manufacturing Based on IoT Technology Guangzhou 510006China UTA Research Institute the University of Texas at ArlingtonFort Worth 76118USA Department of Electrical Engineering and Computer Science University of TennesseeKnoxville 37996USA Oak Ridge National Laboratory Oak Ridge 37830USA Guangdong-HongKong-Macao Joint Laboratory for Smart Discrete Manufacturing Guangzhou 510006China

The concept of reward is fundamental in reinforcement learning with a wide range of applications in natural and social *** an interpretable reward for decision-making that largely shapes the system's behavior has always been a challenge in reinforcement *** this work,we explore a discrete-time reward for reinforcement learning in continuous time and action spaces that represent many phenomena captured by applying physical *** find that the discrete-time reward leads to the extraction of the unique continuous-time decision law and improved computational efficiency by dropping the integrator operator that appears in classical results with integral *** apply this finding to solve output-feedback design problems in power *** results reveal that our approach removes an intermediate stage of identifying dynamical *** work suggests that the discrete-time reward is efficient in search of the desired decision law,which provides a computational tool to understand and modify the behavior of large-scale engineering systems using the optimal learned decision.

关键词： continuous-time state and action decision law learning discrete-time reward dynamical systems reinforcement learning

Optimized Allocation Method of the VSC-MTDC System for Frequency Regulation Reserves Considering Ancillary Service Cost

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CSEE Journal of Power and Energy Systems 2022年第1期8卷 53-63页

作者： Kaiqi Sun Huangqing Xiao yilu liu University of Tennessee Knoxville College of Engineering Ringgold standard institution KnoxvilleTennesseeUnited States

In recent years,the interconnection of asynchronous power grids through the VSC-MTDC system has been proposed and extensively studied in light of the potential benefits of economical bulk power exchanges and frequency regulation reserves *** paper proposes an optimized allocation method for sharing frequency regulation reserves among the interconnected power systems and the corresponding frequency regulation control of the VSC-MTDC system under emergency frequency deviation ***,the frequency regulation reserve classification is *** the classification,the available frequency response capacity reserves of each interconnection are divided into commercial reserves and regular *** the commercial reserves are procured through long-term contracts,the regular reserves are purchased based on market prices of frequency regulation ***,based on the proposed frequency regulation reserve classification,a novel frequency regulation control is then introduced for the VSC-MTDC *** control method could minimize the costs of the disturbed power grid for the needed frequency response supports from the other power *** verifications are performed on a modified IEEE 39 bus system and a highly reduced power system model representing the North American *** simulation verification indicates that the developed frequency regulation control significantly reduced ancillary service costs of the disturbed power grid.

关键词： Frequency regulation control optimized reserve allocation response reserve classification VSC-MTDC

Automated Two-stage Conversion of Hourly Optimal DC Flow Solution to AC Power Flow

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CSEE Journal of Power and Energy Systems 2023年第1期9卷 28-36页

作者： Adedasola A.Ademola Shutang You yilu liu Bredesen Centre and Centre of Ultra-Wide Area Resilient Electrical Energy Transmission NetworksUniversity of TennesseeKnoxvilleTN 37996 USA Centre of Ultra-Wide Area Resilient Electrical Energy Transmission Networks University of TennesseeKnoxvilleTN 37996 USA

Conversion of hourly dispatch cases derived using DC optimal power flow(DCOPF)to AC power flow(ACPF)case is often challenging and requires arduous human analysis and *** paper proposes an automated two-stage approach to solve ACPF formulated from DCOPF dispatch *** first stage involved the use of the conventional Newton Raphson method to solve the ACPF from flat start,then ACPF cases that are unsolvable in the first stage are subjected to a hotstarting incremental method,based on homotopy continuation,in the second *** tasks such as the addition of reactive power compensation and tuning of voltage setpoints that typically require human intervention were automated using a criteriabased selection method and optimal power flow *** datasets with hourly dispatches for the 243-bus reduced WECC system were used to test the proposed *** algorithm was able to convert 100%of the first set of dispatch cases to solved ACPF *** the second dataset with suspect dispatch cases to represent an extreme conversion scenario,the algorithm created solved ACPF cases that satisfied a defined success criterion for 77.8%of the dispatch *** average run time for the hotstarting algorithm to create a solved ACPF case for a dispatch was less than 1 minute for the reduced WECC system.

关键词： AC power flow DC power flow hot-starting algorithm homotopy continuation power flow convergence reactive power compensation voltage setpoint tuning

Machine learning-based fast frequency response control for a VSC-HVDC system

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CSEE Journal of Power and Energy Systems 2021年第4期7卷 688-697页

作者： Kaiqi Sun Huangqing Xiao Shengyuan liu yilu liu University of Tennessee KnoxvilleTN 37996USA University of Tennessee KnoxvilleTN 37996USA and also with the Oak Ridge National LaboratoryOak RidgeTN 37831USA

HVDC system can realize a very fast frequency response to the disturbed system under a contingency because its active power control is decoupled from the frequency ***,most of existing HVDC frequency control strategies are coupled with system primary frequency control and secondary frequency *** the traditional system frequency control is dominated by the thermal generators,the advantage of the fast response of the HVDC system is not made fully *** development of a frequency response estimation based on a machine learning algorithm provides another approach to improve the frequency response capability of the HVDC *** from other frequency deviation tracking strategies,a machine learning based HVDC frequency response control can directly increase the power flow of a HVDC system by estimation of the system generator or load *** this paper,a fast frequency response control using a HVDC system for a large power system disturbance based on the multivariate random forest regression(MRFR)algorithm is *** simulation is carried out with an integrated power system model based on the North American *** simulation results indicate that the proposed MRFR based frequency response control can significantly improve the frequency low point during an event,while stabilizing the frequency in advance.

关键词： Frequency response control multivariate random forest regression VSC-HVDC system

Cross-seam Hybrid MTDC System for Integration and Delivery of Large-scale Renewable Energy

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Journal of Modern Power Systems and Clean Energy 2021年第6期9卷 1352-1362页

作者： Kaiqi Sun Huangqing Xiao Jiuping Pan yilu liu University of Tennessee the Oak Ridge National Laboratory School of Electric Power Engineering South China University of Technology Hitachi ABB Power Grids Research

To better utilize the diversity of renewable energies in the U. S., this paper proposes a cross-seam hybrid multi-terminal high-voltage direct current(MTDC) system for the integration of different types of renewable energies in the U. *** on a developed station-hybrid converter design, the proposed hybrid MTDC system further investigates the connection methods of renewable energies and develops novel flexible power flow control strategies for realizing uninterrupted integration of renewable energies. In addition, the frequency response control of the hybrid MTDC system is proposed by utilizing the coordination between the converters in the hybrid MTDC *** feasibility of the hybrid MTDC system and the performance of its corresponding control strategies are conducted in the PSCAD/EMTDC simulation. The simulation results indicate that the proposed hybrid MTDC system could realize the uninterrupted integration of renewable energies and flexible power transmission to both coasts of U.S.

关键词： Multi-terminal high-voltage direct current(MTDC)system cross-seam interconnection integration of large-scale renewable energies flexible power flow control frequency response control

Controlled Islanding Strategy Considering Uncertainty of Renewable Energy Sources Based on Chance-constrained Model

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Journal of Modern Power Systems and Clean Energy 2022年第2期10卷 471-481页

作者： Shengyuan liu Tianhan Zhang Zhenzhi Lin yilu liu Yi Ding Li Yang the School of Electrical Engineering Zhejiang UniversityHangzhou 310027China the Department of Electrical Engineering and Computer Science University of TennesseeKnoxvilleTN 37996USA the School of Electrical Engineering Shandong UniversityJinan 250061China Electrical and Electronics Systems Research Division Oak Ridge National LaboratoryOak RidgeTN 37830USA

Controlled islanding plays an essential role in preventing the blackout of power *** there are several studies on this topic in the past,no enough attention is paid to the uncertainty brought by renewable energy sources(RESs)that may cause unpredictable unbalanced power and the observabilit>T of power systems after islanding that is essential for back-up black-start ***,a novel controlled islanding model based on mixed-integer second-order cone and chance-constrained programming(MISOCCP)is proposed to address these ***,the uncertainty of RESs is characterized by their possibility distribution models with chance constraints,and the requirements,e.g.,system observability,for rapid back-up black-start measures are also ***,a law of large numbers(LLN)based method is em-ployed for converting the chance constraints into deterministic ones and reformulating the non-convex model into convex ***,case studies on the revised IEEE 39-bus and 118-bus power systems as well as the comparisons among different models are given to demonstrate the effectiveness of the proposed *** results show that the proposed model can result in less unbalanced power and better observability after islanding compared with other models.

关键词： Controlled islanding second-order cone chance-constrained programming renewable energy source(RES) black-start observability.

基于GPC方法的碳排放核算和减排对策研究——以河北省为例

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河南师范大学学报（自然科学版） 2024年第5期52卷 74-83,I0006,I0007页

作者：赵芮熙高小峰李欣豫刘羿鹭邹晓龙河北师范大学商学院石家庄050024 重庆大学环境与生态学院重庆400044 吉林大学公共外交学院长春130012

碳排放核算对评估城市碳排放量和制定减排目标有重要作用.为开发完整、及时的城市级清单,通过自下而上的方法,运用城市碳排放核算工具指南(GPC),同时结合国内和国际参数,以河北省为例,开展包含范围一、范围二、范围三的核算研究.结果表... 详细信息

碳排放核算对评估城市碳排放量和制定减排目标有重要作用.为开发完整、及时的城市级清单,通过自下而上的方法,运用城市碳排放核算工具指南(GPC),同时结合国内和国际参数,以河北省为例,开展包含范围一、范围二、范围三的核算研究.结果表明:根据现有数据核算河北省2019年的碳排放量为175073万tCO_(2)-eq,范围一达到128802万tCO_(2)-eq.与相邻省份相比,河北省碳排放强度最高(4.99tCO_(2)-eq/(万元GDP)),人均CO_(2)排放量仅次于内蒙古自治区,达到每年23.06tCO_(2)-eq.基于以上核算与对比,对清单测算及减排提出如下建议:统一数据分类方案、澄清统计边界原则、丰富统计数据类别、建立企业碳排放报告制度.

关键词：碳排放核算 GPC 能源消耗减排对策

Impact of Simultaneous Activities on Frequency Fluctuations:Comprehensive Analyses Based on Real Measurement Data from the FNET/GridEye

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CSEE Journal of Power and Energy Systems 2021年第2期7卷 421-431页

作者： Shengyuan liu Shutang You Chujie Zeng Yinfeng Zhao Wenxuan Yao yilu liu Zhenzhi Lin Department of Electrical Engineering and Computer Science University of TennesseeKnoxvilleTN 37996USA Department of Electrical Engineering and Computer Science University of TennesseeKnoxvilleTN37996USA College of Electrical Engineering Zhejiang UniversityHangzhou 310027China

Simultaneous human activities,such as the Super Bowl game,would cause certain impacts on frequency fluctuations in power *** the help of FNET/GridEye measurements,this paper aims to give comprehensive analyses on the frequency fluctuations during Super Bowl LIV held on Feb.2,2020,so as to better understand several phenomena caused by simultaneous activities which will help system operations and ***,recent developments of the FNET/GridEye are briefly ***,the frequency fluctuations of the Eastern Interconnection(El),western electricity coordinating council(WECC),and electric reliability council of Texas(ERCOT)power systems during Super Bowl LIV are ***,frequency fluctuations of Super Bowl Sunday and ordinary Sundays in 2020 are ***,the differences of frequency fluctuations among different years during the Super Bowl and their change trends are also ***,several possible explanations,including the simultaneity of electricity consumption at the beginning of commercial breaks and the halftime show,the increasing usage of the Internet,and the increasing size of TV screens,are illustrated in detail in this paper.

关键词： Frequency fluctuation FNET/GridEye simultaneous activities Super Bowl synchrophasor measurement

Attack Detection for Spoofed Synchrophasor Measurements Using Segmentation Network

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CSEE Journal of Power and Energy Systems 2022年第5期8卷 1327-1337页

作者： Wei Qiu Chengcheng Li Qiu Tang Kaiqi Sun yilu liu Wenxuan Yao College of Electrical and Information Engineering Hunan UniversityChangsha 410082China Department of Electrical Engineering and Computer Science University of TennesseeKnoxvilleTN37996USA Oak Ridge National Laboratory Oak RidgeTN37831USA

Synchrophasor measurements are essential to realtime situational awareness of the smart grid but vulnerable to cyber-attacks during the process of transmission and *** ensure data security and mitigate the impact of spoofed synchrophasor measurements,this work proposes a novel object detection method using a Weight-based One-dimensional Convolutional Segmentation Network(WOCSN)with the ability of attack behavior identification and time *** WOCSN,automatic data feature extraction can be achieved by onedimensional convolution from the input signal,thereby reducing the impact of handcrafted features.A weight loss function is designed to distribute the contribution for normal and attack ***,attack time is located via the proposed binary method based on pixel ***,the actual synchrophasor data collected from four locations are used for the performance evaluation of the ***,combined with designed evaluation metrics,the time localization ability of WOCSN is validated in the scenarios of composite attacks with different spoofed intensities and time-sensitivities.

关键词： Data security spoofed synchrophasor measurements weight-based one-dimensional convolutional segmentation network(WOCSN)