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arXiv 2020年

作者： Chen, Kaixuan Lin, Jin Qiu, Yiwei Liu, Feng Song, Yonghua State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100087 China Department of Electrical and Computer Engineering University of Macau 999078 China

To provide automatic generation control (AGC) service, wind farms (WFs) are required to control their operation dynamically to track the time-varying power reference. Wake effects impose significant aerodynamic interactions among turbines, which remarkably influence the WF dynamic power production. The nonlinear and high-dimensional nature of dynamic wake model, however, brings extremely high computation complexity and obscure the design of WF controllers. This paper overcomes the control difficulty brought by the dynamic wake model by proposing a novel control-oriented reduced order WF model and a deep-learning-aided model predictive control (MPC) method. Leveraging recent advances in computational fluid dynamics (CFD) to provide high-fidelity data that simulates WF dynamic wake flows, two novel deep neural network (DNN) architectures are specially designed to learn a dynamic WF reduced-order model (ROM) that can capture the dominant flow dynamics. Then, a novel MPC framework is constructed that explicitly incorporates the obtained WF ROM to coordinate different turbines while considering dynamic wake interactions. The proposed WF ROM and the control method are evaluated in a widely-accepted high-dimensional dynamic WF simulator whose accuracy has been validated by realistic measurement data. A 9-turbine WF case and a larger 25-turbine WF case are studied. By reducing WF model states by many orders of magnitude, the computational burden of the control method is reduced greatly. Besides, through the proposed method, the range of AGC signals that can be tracked by the WF in the dynamic operation is extended compared with the existing greedy controller. Copyright © 2020, The Authors. All rights reserved.

关键词： Model predictive control

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Excellent electrical properties of zinc-oxide varistors by tailoring sintering process for optimizing line-arrester configuration

Excellent electrical properties of zinc-oxide varistors by t...

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International Conference on High Voltage Engineering and Application, ICHVE

作者： Pengfei Meng Wei Cao Chao Chen Shuai Wan Heng Xu Jun Hu Jinliang He Tsinghua University Beijing China Wuhan NARI Limited Liability Company State Grid Electric Power Research Institute Wuhan China Guangdong Aikang Electric Power Co. Ltd Guangzhou China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (数字)9781728155111

ISBN: (纸本)9781728155128

We optimized the excellent electrical performance of zinc-oxide (ZnO) varistors doping of aluminum and indium by tailoring the sintering process. The surface morphology, nonlinear volt ampere properties, capacitance-voltage characteristics, and dielectric analyses were carried out. At a given aluminum and indium concentration, the average sample grain size ( d) increased as lengthening sintering time from 0.5 to 2.5 h. The voltage gradient ( E1mA) decreased from 602.4 V/mm to 356.7 V/mm. The residual voltage of the sintered varistors at the lightning impulse current ( 8/20 μs) decreased as the samples sintering holding time extended from 0.5 to 2.0 h. When the ZnO varistor was sintered for 1.5 h, the samples showed an excellent performance, with a reference voltage of 479.3 V/mm at 1 mA DC. When assembled in the line surge arresters, the obtained high-voltage-gradient ZnO varistors can decrease their length and residual voltage, which allows for better coordination of the line surge arrester with the insulators. This study has great significance to optimize line-arrester configurations and improve power-system stability.

关键词： Zinc oxide Varistors Arresters II-VI semiconductor materials Surges Insulators Dielectrics

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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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2019 IEEE Sustainable power and Energy Conference, iSPEC 2019

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

ISBN: (纸本)9781728149301

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. © 2019 IEEE.

关键词： Battery management systems

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Online detection method for internal fault of permanent magnet synchronous generator based on new type of search coil

Online detection method for internal fault of permanent magn...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Daizong Tian Yuguang Sun Wei Du Lin Gui State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing People's Republic of China

ISBN: (纸本)9781728133997

In order to overcome the limitations of traditional fault diagnosis methods, this paper studies the online detection method of internal faults for permanent magnet synchronous generators (PMSG) based on the new type of search coil. Taking a 6-phase PMSG as an example, two types of search coil are fixed in the air gap according to the pole-pair number and the armature winding structure. A calculation method for the induced EMF of the new type of search coil in the PMSG is presented, which is verified by the model machine experiment. simulation and experiments on the 6-phase PMSG show that the open-circuit voltage of the search coil was zero under normal operation, while an obvious EMF was induced in the search coil once the internal asymmetry fault occurred. And according to the period of the voltage, the fault could be distinguished between the internal fault of the stator winding and the demagnetization fault. Based on the new type of search coil, this paper provides a new way for online monitoring of internal faults of PMSGs.

关键词： Circuit faults Stator windings Harmonic analysis Magnetic fields Windings Generators Demagnetization

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The Design and Field Test of a Shunt Unified power Quality controller for Mitigating Voltage Sags

The Design and Field Test of a Shunt Unified Power Quality C...

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IEEE Student Conference on Electric Machines and systems

作者： Chang Liu Lin Xu Wei Wei Yingdong Wei Hua Yang Xueyuan Liu Yi Zhang Ying Wang Electric Power Research Institute of State Grid Sichuan Electric Power Company Chengdu China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China School of Electrical Engineering and Automation Fuzhou University Fuzhou China College of Electrical Engineering Sichuan University Chengdu China

ISBN: (数字)9781728156224

ISBN: (纸本)9781728156231

A shunt unified power quality controller (S-UPQC) is developed and has been tested in the field in order to confirm its performance at mitigating voltage sags for sensitive power consumers. The S-UPQC keeps the magnitude of the voltage supply for power consumers constant by acting as a voltage source when voltage sags occur in the power grid. In this paper, a smooth switching strategy is designed to smooth the voltage disturbance of power consumers when the power supply switches between the S-UPQC and the grid. simulation results are presented to show its high performance. A prototype of S-UPQC is developed and a field test has been conducted. During its operation, the performance of the SUPQC at mitigating voltage sags within actual power systems is confirmed.

关键词： simulation power quality Prototypes Switches Production Reliability Switching circuits

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Thermal Analysis of Internal Short-Circuit Faults in Stator Windings of Multiphase Permanent Magnet Synchronous Generator with Rectifier-load system

Thermal Analysis of Internal Short-Circuit Faults in Stator ...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Daizong Tian Yuguang Sun Wei Du Lin Gui State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing People's Republic of China

The multiphase permanent magnet synchronous generator (PMSG) with rectifier-load systems have been widely used in the mobile platforms that requires high power supply system security. Taking a 6-phase rectifier PMSG as an example, a multi-loop combined with FEM mathematical model is established to analyze the internal short-circuit of stator windings, and a series of fault experiments are carried out on a 6-phase model machine. Using the mathematical model, all the voltages and currents of stator windings are calculated out in both normal operation and various internal short-circuit faults. The simulation results are consistent with the experiment data, which verifies the correctness of the mathematical model. In addition, the simulation currents of the windings could be substituted into the 2D-FEM temperature field calculation model, then the internal temperature field distribution of the model machine under various metallic inter-turn and phase-to-phase short-circuit faults are obtained. The variation analysis of the internal temperature field corresponding to different internal faults provides a basis for the internal fault detection.

关键词： Mathematical model Stator windings Rectifiers Windings Generators Resistance Permanent magnets

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Analysis of fatigue life loss of drivetrain of doubly-fed wind turbines under short-circuit fault of power grid 8

Analysis of fatigue life loss of drivetrain of doubly-fed wi...

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8th Renewable power generation Conference, RPG 2019

作者： Shilong, Qiu Hui, Li Lijiao, Gong Bin, Wang Zhaoseng, Chai You, Wu Department of Mechanical and Electrical Engineering Shihezi University Shihezi China State Key Laboratory of Power Drivetrain Equipment and System Security Chongqing University Chongqing China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Haidian District Beijing China

ISBN: (纸本)9781839531255

The shafting drivetrain of the doubly fed wind turbine is the part with the highest failure rate. The electromagnetic torque fluctuation caused by the grid fault easily results in the torsional vibration fatigue loss of the shaft. Accordingly, the influences of drivetrain fatigue life loss under different grid faults require investigation. Firstly, the four-mass model of the drivetrain is constructed on the basis of MATLAB/Simuhnk. Secondly, the electromagnetic torque response under short-circuit fault of the grid is obtained via model simulation. Finally, the effects of different types of grid faults on the fatigue life of the drivetrain are analysed through Mlife. Results show that the electromagnetic torque fluctuation load generated by grid fault has no apparent influence on the fatigue life of the drivetrain in the short term. but the cumulative effect of short-term damage will aggravate the fatigue life loss of the drivetrain and increase the failure risk of the component. The electromagnetic torque generated by the three-phase symmetrical short-circuit is the most violent and has the maximum effect on the fatigue life of the drivetrain. © 2019 Institution of Engineering and Technology. All rights reserved.

关键词： Timing circuits

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The parameter design method of smoothing inductance based on MMC-MTDC with R-type superconducting fault current limiter

The parameter design method of smoothing inductance based on...

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The 16th IET International Conference on AC and DC power Transmission (ACDC 2020)

作者： P. Guo Z. Yuan G. Liu Y. Zhao Z. Shi Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Beijing China Shenzhen Power Supply Corporation Shenzhen China Sichuan Energy Internet Research Institute Tsinghua University Chengdu China

The rapid increase of voltage sourced converter brings the great development of the multi-terminal DC technology, both in the DC transmission and DC distribution fields. However, because of the weak impedance characteristic of the VSC-HVDC system, how to suppress and clear DC fault currents becomes a challenge. Considering the stability, the response speed and the system structure, it is not possible to apply excessive inductance at the DC side, hence, the current limiting effectiveness is relatively restricted. On the one hand, with the effective properties, Resistive type Superconducting Fault Current Limiter (R-SFCL) becomes an effective device to solve the problem of VSC-HVDC system under DC faults. On the other hand, because of dynamic energy-impedance characteristics of R-SFCL, the fixed impedance selection method at a certain time to carry out dynamic current limiting analysis is no longer applicable. Therefore, the DC fault current research and R-SFCL characteristic are comprehensively analyzed firstly in this paper. Based on that, a smoothing inductance determination method is proposed to cut off the DC fault current by DC breaker and ensure the continuous operation of remaining parts. Finally, based on a multi-terminal DC system simulation, the improvement and effectiveness of the proposed method are validated.

关键词： power transmission faults HVDC power transmission superconducting fault current limiters HVDC power convertors voltage-source convertors

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Discrete State Event-Driven Framework for simulation of Switching Transients in power Electronic systems

Discrete State Event-Driven Framework for Simulation of Swit...

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IEEE Energy Conversion Congress and Exposition

作者： Yicheng Zhu Zhengming Zhao Bochen Shi Jiahe Ju Zhujun Yu Liqiang Yuan Kainan Chen State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

Accurate and efficient simulation of device-level switching transients together with system-level dynamics in power electronic systems is challenging due to stiffness and intensive discontinuous points introduced by discrete system events. In this paper, a switching transient simulation mechanism is proposed to combine the discrete state event-driven (DSED) simulation framework and the piecewise analytical transient (PAT) model together to overcome such difficulties. Key elements of this simulation framework for switching transient simulation include: 1) a commutation-unit-based (CUB) method for switching transient simulation and 2) a time-scale-decoupling (TSD) simulation mechanism. The proposed simulation framework is applied to a 50kVA solid-state transformer (SST) to verify its accuracy and efficiency. DSED simulated and experimental waveforms are in excellent agreement. Up to 5.3-fold and 717.3-fold improvements in simulation speed are achieved at the same level of accuracy compared with Simulink simulation with ideal switch models and Saber simulation with physics-based device models, respectively.

关键词： Transient analysis Switches Integrated circuit modeling Switching circuits Mathematical model Computational modeling

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Key technologies of the operational reliability evaluation for the large-scale battery energy storage system 7

Key technologies of the operational reliability evaluation f...

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7th International Conference on Reliability of Electrical Products and Electrical Contacts, ICREPEC 2019

作者： Cheng, Lin Wan, Yuxiang Jiang, Yi Wang, Zhidong Liu, Mei State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing100084 China State Grid Economic and Technological Research Institute Corporation Limited State Grid Corporation of China Beijing102209 China

ISBN: (纸本)9789881532343

The large-scale battery energy storage system (BESS) can effectively meet the diversified needs of power grid dispatching. Therefore, the improvement of the BESS operational reliability is of great significance to ensure the operation safety of the grid. However, the BESS is composed of a large number of batteries. This fact suggests the BESS reliability depends not only on the battery operating state but also on the strategy of battery networking reconfiguration. In this paper, the analysis of the operational reliability research of largescale BESS is carried out in-depth. The research status of reliability of large-scale BESS is investigated, and some thoughts on the obstacles to the BESS operational reliability evaluation are given. The promotion of the new technology of BESS and the development of the ubiquitous Internet of Things on BESS operation reliability are analyzed. In addition, the framework of the operational reliability evaluation of a large-scale BESS is proposed. Some key technologies such as failure mechanism, equipment reliability modeling, evaluation, and optimization are summarized, providing some suggestions for the application of large-scale BESS. © 2019 by International Academic Publishers Ltd.

关键词： Electric batteries

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