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An unsupervised hourly weather status pattern recognition and blending fitting model for PV system fault detection

Applied Energy 2022年 319卷

作者： Jiaqi Qu Zheng Qian Yan Pei Lu Wei Hamidreza Zareipour Qiang Sun School of Instrumentation and Optoelectronic Engineering Beihang University Beijing China School of Electronics and Information Engineering Beihang University Beijing China The Department of Electrical and Computer Engineering University of Calgary Calgary Canada State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

Detecting PV system faults in a timely fashion is important to ensure the safe operation of equipment and reduce their impact on the economy of the PV systems. It is necessary to further improve the time-sensitive performance evaluation of the system. However, the hourly weather scenario segmentations are seldom considered during the hour-level online monitoring process. Therefore, a hybrid method based on unsupervised hourly weather status pattern recognition and blending fitting model is proposed for hourly fault detection to improve the performance evaluation of PV systems. The proposed solution includes three parts, firstly, in the data preprocessing stage, the measured power with the errors and noise under normal operation situation caused by the environment changes is corrected by monthly linear fitting. Secondly, an unsupervised hourly weather status pattern recognition method is constructed using the measured radiation data, including unsupervised clustering and the Multiclass-GBDT-LR classification process. Finally, after eliminating the anomalies and errors, the blending fitting model of the hourly sub-weather status is established. Through the analysis of power plants in Australia and China, the proposed solutions are validated and evaluated to be superior to existing data-driven solutions in terms of fitting accuracy, detection validity, and response time. Numerical results of case studies indicate that the developed methodology under sub-weather has improved the detection accuracy up to 97.71% and 99.29% compared to benchmark models.

关键词： Photovoltaic systems performance Hourly fault detection Unsupervised hourly weather status pattern recognition Blending fitting model

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Flexible unbalanced control with peak current limitation for virtual synchronous generator under voltage sags

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Journal of Modern power systems and Clean Energy 2018年第1期6卷 61-72页

作者： Tianwen ZHENG Laijun CHEN Yan GUO Shengwei MEI State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Qinghai Key Lab of Efficient Utilization of Clean Energy New Energy Photovoltaic Industry Research Center Qinghai University

Virtual synchronous generator(VSG)is gridfriendly for integrating distributed generations(DGs)since it can emulate the operation mechanism of traditional synchronous generator(SG).However,the traditional VSG control strategy,which is mainly suitable for balanced voltage conditions,may lead to power oscillations,current unbalance and even overcurrent under unbalanced voltage *** overcome this difficulty,a flexible unbalanced control with peak current limitation for VSG under unbalanced operating conditions is *** on the basic VSG control algorithm,the control strategy integrates two novel control modules,which are current reference generator(CRG)and power reference generator(PRG).The proposed control strategy can flexibly meet different operation demands,which includes current balancing,constant active or reactive *** the injected currents are kept within safety values for a better utilization of the VSG power ***,the experimental platform is *** results demonstrate the validness and effectiveness of the proposed control strategy.

关键词： Virtual synchronous generator Unbalanced control Current reference generator power reference generator Voltage sags

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Coordinated Wholesale and Retail Market Mechanism for Providing Demand-side Flexibility

Coordinated Wholesale and Retail Market Mechanism for Provid...

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Sustainable power and Energy Conference (iSPEC)

作者： Gang Luo Yujun He Chen Zhao Xuan Zhang Shaohua Lin Yue Zhao Dispatch and Control Center Guangdong Power Grid Co. Ltd Guangzhou China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

With the trend of electricity market deregulation for recent decades, the consumers at demand-side are progressively encouraged to trade the power in competitive market environment. Conventionally, only large-scale consumers participate directly in the wholesale market that adopts spot energy pricing. Most small-scale consumers are involved in the retail market that offers non-varying tariff predefined by retailers or utility companies. In this work, we investigate a framework of coordinated wholesale and retail market structure that enables consumers in the retail market to reflect the spot price and improve the power system flexibility for the high penetration of renewables. Then, market behaviors of demand-side participants with the proposed market mechanism and some related business models are discussed. The following participation modes for consumers could be opted including: direct trade, trade agented by retailers or organized in virtual power plant (VPP). For a pool-based trade at demand-side, a bi-level market clearing mechanism at transmission and distribution levels is explained. This mechanism seeks to optimize the global demand profile for hosting renewables while solving the operating constraint of loads and local networks. This study can offer constructive advises to promote further development of China's electricity market.

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Research on Equalization Effect of Dynamic Reconfigurable Battery Management system

Research on Equalization Effect of Dynamic Reconfigurable Ba...

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Sustainable power and Energy Conference (iSPEC)

作者： Yuxiang Wan Lin Cheng Yi Jiang Zhidong Wang Mei Liu State Key Lab. of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China State Grid Economic and Technological Research Institute Corporation Limited State Grid Corporation of China Beijing China

ISBN: (纸本)9781728149318

The battery differences not only affect the reliability and security of battery packs but also accelerate the decline of the packs' life. Although battery management systems (BMS) and equalization circuit can be used to balance the differences, only the whole battery pack can be protected with high-cost and complex circuits. Dynamic reconfigurable battery management system (DRBMS) based on networked control has a simple principle and can shield the differences of battery cells. This paper designs experiments for the dynamic reconfigurable battery network technology and makes a contrast with the traditional BMS. Through the analysis of voltage, SOC difference and dynamic resistance during charging and discharging, the results show that DRBMS has better voltage and capacity equalization effect than BMS. The cells of paralleled battery packs can be fully charged/released in DRBMS. It is also verified that DRBMS is applicable on decommissioned bus battery packs which are of larger differences and the ladder utilization.

关键词： dynamic reconfigurable battery management equalization effect decommissioned battery battery difference Battery Pack Battery management systems configurability Dynamic resistance Equalization Batteries network control

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Analysis of Adaptive Re-closure in AC-DC Hybrid power system

Analysis of Adaptive Re-closure in AC-DC Hybrid Power System

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International Conference on Advanced power system Automation and Protection (APAP)

作者： Min Xie Wei Zhang Ludeng Liu Xin Jia Bin Wang Xinzhou Dong Dispatching and Controlling Center of Anhui Electric Power Company State Grid Hefei China Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University China

ISBN: (数字)9781728117225

ISBN: (纸本)9781728117232

The beat frequency characteristic of the recovery voltage of fault phase in the case of single-phase grounding transient fault happening to line with the shunt reactors is analyzed. Besides, the paper analyzes the reason of no beat frequency phenomenon of transient fault happening to line without shunt reactor. The AC power networks with metallic grounding fault and arc grounding fault are analyzed by simulation. The recovery voltage of single-phase grounding fault in AC/DC hybrid power grid is studied by PSCAD. The new problems of the adaptive re-closure in AC-DC hybrid power system are discussed. Then the follow-up ideas to solve several existing problems are also presented.

关键词： Circuit faults Inductors Shunts (electrical) Transient analysis Integrated circuit modeling Grounding Capacitance

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Research on inter-turn short circuit of armature windings in the multiphase synchronous generator-rectifier system

Research on inter-turn short circuit of armature windings in...

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作者： Sun, Yuguang Wang, Shanming Huang, Ziguo Mu, Shujun State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

The multiphase synchronous generator-rectifier system could provide an ideal DC power source for more electric aircraft (MEA). When the inter-turn short-circuit fault occurs in phase windings of the generator, a large short-circuit current would be introduced inside the armature windings, which could cause severe damages to the system for overheat in the windings and irons as well as huge electromagnetic forces on the end coils. To improve the reliability of the MEA, this study researches on the inter-turn fault of the multiphase generator-rectifier system, including the theoretical analysis, numerical simulation and experimental verification. A 12-phase system is taken for example, and a multi-loop mathematical model is built up to calculate all voltages and currents in the multiphase synchronous generator-rectifier system with armature inter-turn fault. Many factors are thoroughly considered in the model, including the location and short-turns of fault, space harmonics of air-gap magnetic field and the changing circuit topology of the system. The mathematical model is verified by fault experiment results. Moreover, the electric characteristics of the fault are summarised, which could provide a quantitative basis for early detection of the inter-turn faults in the multiphase generator-rectifier system. © 2018 Institution of Engineering and Technology. All rights reserved.

关键词： More electric aircraft

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Modeling and simulation analysis of dual-rotor vibration system with multiple faults

Modeling and simulation analysis of dual-rotor vibration sys...

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Society for Machinery Failure Prevention Technology Conference 2018: Intelligent Technologies for Equipment and Human Performance Monitoring, MFPT 2018

作者： Yang, Yizhou Liu, Chao Jiang, Dongxiang Yang, Wenguang State Key Lab. of Control and Simulation of Power Systems and Generation Equipment Department of Thermal Engineering Tsinghua University Beijing100084 China

Dual-rotor system is an important rotor form in rotating machinery like gas turbine engine. Its complex structure results in rich dynamical behaviors and more probability to failure. The modeling and simulation of the dual-rotor system can help to understand its dynamic characteristics and provide theoretical support for the design, operation and maintenance. In this paper, a dynamic model of a dual-rotor system with multiple rotor faults is established. The dual-rotor vibration model without any fault is built by finite element method, where the two shafts are connected by an inter-shaft bearing and nonlinear models of rolling element bearing and squeeze film damper are considered. The numerical integration method of Newmark-β is used to obtain the steady-state vibration response of the system. Then rotor faults are introduced to the system model, including unbalance, misalignment, looseness and rub-impact. The steady-state responses of single faults in the dual-rotor system are analyzed and typical fault features are obtained. Then coupling characteristics between different rotor faults, and the influences of the squeeze film dampers on the dynamic characteristics and fault features of the system are studied. © 2018 Proceedings of the 9th International Symposium on Imprecise Probability.

关键词： Rotating machinery

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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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CCF early warning method of LCC-HVDC based on XGBoost algorithm

CCF early warning method of LCC-HVDC based on XGBoost algori...

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8th Renewable power generation Conference (RPG 2019)

作者： Zhizhong Li Bin Wang Haigang Wang Bin Yu Min Xie Shi Chen Xinzhou Dong Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China State Grid Anhui electric power company Hefei 230061 China

ISBN: (数字)9781839531248

ISBN: (纸本)9781839531255

The lack of analytical mechanism of continuous commutation failure (CCF) process hinders the development of CCF early warning algorithm and further obstructs the coordination strategy of relay protection between AC and DC size in hybrid grid. However, summarizing the protection threshold of CCF in the form of electrical quantity analytically under different fault types is a nontrivial pattern recognition problem. To overcome the difficulty of directly analysing the electromagnetic process of CCF, a statistical learning modelling approach is adapted to propose a CCF warning system, in which XGBoost algorithm was used as the backbone to regress on the relationship between AC/DC electrical quantities and the possibility of the occurrence of CCF. The design of the feature vector in XGBoost-based classifier considers not only the analytical expression of key electrical quantity during single commutation failure but also the important state variable of control system. Additionally, a special data windowing method was proposed to enrich of information encoded by the feature vector while ensuring the speed requirement posed by the protection system. Validation on multi-fault scenes simulation shows that the proposed early warning system can trigger warning signal correctly with sufficiently small measured data required, proving the practicability in engineering practice.

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Accommodating Renewable Energy Sources into the Modern power system via a General Coordinated Mechanism

Accommodating Renewable Energy Sources into the Modern Power...

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IEEE power and Energy Society General Meeting

作者： Jing Yu Ye Guo Hongbin Sun Shenzhen Environmental Science and New Energy Technology Engineering Laboratory Tsinghua-Berkeley Shenzhen Institute Tsinghua University Shenzhen China State Key Lab of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China

In order to better accommodate renewable energy sources (RESs), a general coordinated mechanism for modern power system has been proposed, which is simultaneously appropriate for economic dispatch and market clearing under the current structure of wholesale markets. In which, the system operator can achieve a global optimum under uncertainties by investing independent aggregators (IAs) with better autonomies on trade-offs between expected profits and risks. Meanwhile, IAs with RESs are free to model their internal uncertainty in a heterogeneous manner and integrate the local information into tailored bids without revealing privacy. Moreover, a parametric-programming-based distributed (PPD) algorithm is designed to support the once-daily communication mechanism. The case studies validated the performance of the proposed mechanism.

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