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Real-time charging optimization method considering vehicle charging prediction

Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第9期38卷 61-68页

作者： Li, Zhengshuo Guo, Qinglai Sun, Hongbin Xin, Shujun Department of Electrical Engineering Tsinghua University Beijing100084 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing100084 China

With large-scale electric vehicles (EVs) integrated into the power system, how to optimize EV charging power in real time to avoid incremental peak load and achieve valley-filling will be important. The regular real-time charging optimization as well as the vehicle charging prediction method is reviewed at first. Since vehicle charging (especially vehicle fleet charging) is predictable, a new real-time charging optimization model is proposed on the basis of the regular method with the consideration of the prediction model of incoming EVs. The new model is solved with receding horizon optimization, obtaining the current optimized charging power of plugged EVs. Through case study with various prediction accuracies, it can be seen that the proposed method always approaches the optimal solution to valley-filling. Moreover, compared with regular method, the proposed method would make a greater improvement of optimization result in the case of more diverse EV plug-in time. ©2014 state Grid Electric power Research Institute Press.

关键词： Forecasting

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Autonomous-synergetic energy management system family for smart grids: concept, architecture and cases

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Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第9期38卷 1-5and14页

作者： Sun, Hongbin Zhang, Boming Wu, Wenchuan Guo, Qinglai Department of Electrical Engineering Tsinghua University Beijing100084 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing100084 China

Energy management system (EMS), known as the brain of power grid, utilizes information flow to control energy flow so as to keep power grid operation efficient and secure. Conventionally, the EMS is a centralized one with both information collecting and decision-making centralized. This architecture is facing a serious challenge in mass information collecting and faster decision, especially in smart grid environment. A new concept of distributed autonomy and centralized synergy is proposed and the EMS family covering all sections of smart grids (e.g. source, grid and demand) is concretized. Both commonness and individuality of these EMS family members are discussed. Several new members of EMS family including wind farm EMS, substation EMS and electric vehicle (EV) aggregator EMS are presented, to demonstrate their autonomous characteristic. Interaction among EMS family members is introduced to coordinate the members so as to implement source-grid-demand synergy to form an EMS family network. Several examples of interaction among the EMS family, such as interactions between transmission and distribution, between substations and control center, and between wind farm and EV aggregator, are introduced. ©2014 state Grid Electric power Research Institute Press.

关键词： Energy management systems

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Applications and Prospects of Online Insulation Monitoring Technique Based on Broadband Frequency Response for Transformers in Voltage Source Converter System 2nd

Applications and Prospects of Online Insulation Monitoring T...

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Conference Proceedings of 2022 2nd International Joint Conference on Energy, Electrical and power Engineering

作者： Lu, Geye Zheng, Dayong Zhang, Pinjia State Key Lab of Security Control and Simulation of Power Systems and Large Scale Generation Equipment Tsinghua University Beijing100084 China

ISBN: (纸本)9789819943333

power electronic converters are widely applied in new power system. Converter transformers have a critical risk in safe and reliable operation due to the insulation ageing. At present, conventional transformer insulation monitoring methods are limited to low sensitivity, invasive sensors and sophisticated evaluation. The goal of this paper is to improve the performance of online insulation monitoring for converter transformers based on broadband frequency response. The significance of application promotion, the disadvantages of existing methods and the challenges from offline to online implementation are clarified. A novel technique based on inherent harmonics in voltage source converter system is investigated, which provides the prospect in improving the online monitoring performance with high reliability and non-invasiveness nature. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Insulation

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Degradation state assessment of rolling bearing based on variational mode decomposition and energy distribution 16th

Degradation state assessment of rolling bearing based on var...

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16th International Conference on Fracture and Damage Mechanics, 2017

作者： Han, Te 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

ISBN: (纸本)9783035711684

Degradation state assessment of bearing is an important part of prognostic and health management (PHM) in rotating machinery. Generally, the energy distribution of frequency band is sensitive to degradation state for rolling bearing. Hence, a novel assessment method based on variational mode decomposition (VMD) and energy distribution is proposed in this work. Firstly, the VMD is used to decompose raw vibration signal into several components with different scales and frequency bands. These components is capable of reflecting the local characteristic of vibration signal. Then, the energy distribution of these components is utilized as feature vector. Finally, the different bearing states can be classified by the scatter plots of the first several principal components after principal component analysis (PCA). The analysis of an experimental dataset demonstrates the effectiveness of this methods. The comparative analysis shows the VMD is superior to traditional empirical mode decomposition (EMD) methods. © 2017 Trans Tech Publications, Switzerland.

关键词： Variational mode decomposition

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Rolling bearing fault feature extraction of casing vibration signal

Rolling bearing fault feature extraction of casing vibration...

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Society for Machinery Failure Prevention Technology Annual Conference 2017: 50 Years of Failure Prevention Technology Innovation, MFPT 2017

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

The health of rolling bearing plays an important part in the operation of rotating machinery like gas turbine engine. Health monitoring and fault diagnosis of rolling bearings based on vibration signals have been through great development these years. But when sensors are set on the casing instead of the bearing pedestal, and the surrounding structure is very complex, the diagnosis problem becomes much more complicated, which brings more challenges to the signal processing. In this paper, a set of signal processing methods are used to enhance and extract the impact features from casing vibration signals, and to realize the detection of rolling bearing faults. Aself-adaptive decomposition method called intrinsic time-scale decomposition (ITD) is applied to decompose the vibration signal into a series of proper rotation components and a monotonic trend, helping to extract dynamic features of the signal. Teager-Kaiser energy operator is a simple algorithm calculating the energy of a signal and is very sensitive to transient impact faults. As the fault feature transmitted to the casing is relatively week, autoregressive model (AR) and minimum entropy deconvolution (MED) are to enhance the non-stationary impact components. Experiments are taken on the rotor-bearing-casing test rig with minor defects in themain shaft bearing. Testing on the casing vibration signal, this fault feature enhancing and extracting method shows its remarkable ability in rolling bearing fault diagnosis.

关键词： Feature extraction

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Research and simulation on voltage stability control strategy for AC port of power electronic transformer 16

Research and simulation on voltage stability control strateg...

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16th IET International Conference on AC and DC power Transmission, ACDC 2020

作者： Shen, Yu Nie, Haozhe Cai, Weiqian Yuan, Liqiang Zhang, Chunpeng Zhao, Zhengming State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9781839533914

With wide application of power electronic equipment in power system, voltage stability and power supply reliability need to be improved. In this paper, voltage sag caused by AC port load increase and the influencing factors are studies with a typical power electronic transformer topology as example. A calculation method which can estimate the port voltage sag performance according to the load impedance is proposed. In order to maintain the port voltage stability in the process of load increase, a voltage stability control strategy is proposed based on the double-loop control by increasing the voltage feedforward, which can improve the power supply quality and stability of power electronic transformer. Finally, the MATLAB/Simulink simulation results show that the proposed scheme is accurate and effective. © 2020 Institution of Engineering and Technology. All rights reserved.

关键词： MATLAB

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Secondary voltage control considering rapid dynamic reactive power compensation

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Dianli Xitong Zidonghua/Automation of Electric power systems 2015年第2期39卷 53-60页

作者： Wang, Xuran Guo, Qinglai Sun, Hongbin Wang, Bin Zhang, Mingye Zhang, Boming Department of Electrical Engineering Tsinghua University Beijing100084 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing100084 China

This paper presents a secondary voltage control system considering rapid dynamic var compensators, such as static var compensator/static synchronous compensator (SVC/STATCOM). In order to take full advantage of the rapid adjustment feature of SVC/STATCOM in static voltage control and transient voltage stability, two independent control stages are dealt with. In the first stage, SVC/STATCOM and conventional var compensators are incorporated in the coordinate secondary voltage control model to bring the rapid adjustment feature of SVC/STATCOM into full play. In the second stage, a quadratic programming model is designed to do the optimal control of the dynamic reactive power reserves. The reactive power compensation of the slow dynamic var compensators is substituted for that of SVC/STATCOM, and the dynamic reactive power reserves level is improved. Through coordination between sequence and space, all kinds of reactive power compensators are made full use of in the secondary voltage control and transient voltage stability prevention control. Nordic system test results show that the system can greatly improve the response speed of traditional secondary voltage control while avoiding the conflict between SVC/STATCOM and the traditional reactive power compensators. At the same time, the system is able to carry out effective preventive control of transient voltage stability and improve the recovery effect of system voltage after the disturbance. ©, 2015 state Grid Electric power Research Institute Press.

关键词： Reactive power

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The harmonic characteristics analysis of offshore wind farms transmitted by the submarine cable based on time domain simulation 6

The harmonic characteristics analysis of offshore wind farms...

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2021 6th International Symposium on Advances in Electrical, Electronics and Computer Engineering, ISAEECE 2021

作者： Li, Jingyi Yang, Jianjun Shi, Zhaohui Wang, Ke Li, Haozhi Xie, Xiaorong Li, Fangfeng Key Laboratory of Far-shore Wind Power Technology of Zhejiang Province Hangzhou Zhejiang311122 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Haidian District Beijing100084 China

The harmonic amplitude may exceed the limit when the large scale of wind farm is connected to the weak AC system through AC submarine cable. The harmonic with high amplitude will endanger the safety of power equipment, and even affect the normal integration of large-scale wind farm. This paper takes an actual offshore wind power connected to the system through AC submarine cable as an example. On the basis of building the model of the system in the PSCAD/EMTDC simulation software. The simulation calculation is systematically carried out. The effect of multiple factors on the harmonic characteristics is analyzed. The preliminary explanation for the harmonic amplitude out of limit is given for the actual large scale of wind farm connected to the weak AC system through AC submarine cable. © Published under licence by IOP Publishing Ltd.

关键词： Time domain analysis

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A robust interval economic dispatch method accommodating large-scale wind power generation. Part one: Dispatch scheme and mathematical model

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Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第20期38卷 33-39页

作者： Li, Zhigang Wu, Wenchuan Zhang, Boming Department of Electrical Engineering Tsinghua University Beijing100084 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing100084 China

Large-scale wind power integration imposes technical challenges to the power system operation and scheduling. Traditional deterministic generation dispatch methods cannot ensure system operation security because they don't incorporate wind power uncertainties appropriately. A new robust dispatch scheme based on the wind power prediction interval is introduced for intra-day active power dispatch, in which wind farms are controlled with the maximum-power-point-tracking strategy mostly. This scheme is featured with flexibility and practicality. In combination with this scheme, a robust interval economic dispatch model is formulated as a robust optimization method and further simplified as a quadratic programming, taking the response of AGC regulation into consideration. Finally, Monte Carlos simulations are conducted on a modified IEEE 24-bus system to compare performance of the proposed approach and the traditional one, and the robustness, reliability and economy of the robust dispatch scheme is verified. © 2014 state Grid Electric power Research Institute Press

关键词： Quadratic programming

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Automatic voltage control for ultra-high voltage AC neighboring grids

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Dianli Xitong Zidonghua/Automation of Electric power systems 2013年第21期37卷 99-105页

作者： Wang, Bin Guo, Qinglai Sun, Hongbin Tang, Lei Zhang, Boming Wu, Wenchuan Department of Electrical Engineering Tsinghua University Beijing 100084 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing 100084 China

The connection of ultra-high voltage (UHV) transmission line has brought a challenge to the voltage operation and control of its neighboring power system. Facing engineering practice, this paper proposes an automatic voltage control (AVC) method for the UHV neighboring grids. The reactive voltage operation and control characteristics of UHV neighboring grids are analyzed, including the tremendous impact of UHV active power flow change on the bus voltage in UHV neighboring grids, the large voltage fluctuation, and the tight coupling among power plants and substations, etc. The smart voltage optimal control technology is proposed and implemented by taking into consideration these characteristics and the coordinated control among tightly coupled power plants and substations in the UHV neighboring grids. This method can reduce the irrational reactive power flow and bypass the unnecessary discrete device action, while ensuring voltage security. The proposed method is put into closed-loop field operation in China for its validated efficiency and practicability. ©2013 state Grid Electric power Research Institute Press.

关键词： Smart power grids

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