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Field PMU Test and Calibration Method——PartⅡ:Test Signal Identification Methods and Field Test Applications

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Journal of Modern power Systems and Clean Energy 2023年第1期11卷 243-253页

作者： Sudi Xu Hao Liu Tianshu Bi State Key Lab of Alternate electric power System with Renewable Energy Sources(north china electric power university) Beijing 102206China State Grid Jangsu electric power CO. LTD Research InstituteNanjing 211103China

Synchrophasor measurement units(PMUs)provide synchronized measurement data for wide-area *** improve the effectiveness of synchrophasor-based applications,field PMUs must be tested to ensure their performance and data *** the companion paper(Part I),we proposed a field PMU test and calibration framework consisting of a PMU calibrator and analysis *** I presents the development and test of the PMU *** paper focuses on the analysis center and field test ***,the critical component of the analysis center is the signal identification module,for which the step and oscillation signal identification methods are ***,the performance evaluation criteria of PMU in these two cases are different from *** methods include a step signal detection method based on singular value decomposition(SVD),which has the capability of weak step detection to account for energy leakage of the signal during the step process,and an oscillation signal identification method based on SVD and fast Fourier transform,which can accurately extract oscillation components that benefit from the adaptive threshold setting ***,the analysis center software is implemented based on identification *** integrating the PMU calibrator in Part I with the analysis center in Part II,we can examine in depth the field PMU test applications in three test scenarios,including standard,playback,and field signal *** demonstrate the effectiveness and applicability of the proposed field PMU test methods from both Parts I and II.

关键词： Phasor measurement unit(PMU) field test signal identification oscillation

Experimental study and analysis on the rising motion of grains in a vertically-vibrated pipe

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Chinese Physics B 2015年第3期24卷 224-229页

作者：刘煜赵俊红 electric power research institute Henan Electric Power Company Luoyang College Civil Aviation Flight University of China

Previous experimental investigations have shown that when a narrow pipe is inserted into a granular bed and is vibrated vertically but the granular bed is kept still, the grains in the bed can enter the pipe and rise against gravity along the pipe and finally stabilized at a certain height. The growth velocity and final stable height of the grain column inside the pipe can be controlled by varying the vibration conditions. In this paper, we discuss those experimental findings. We establish a mathematic relation between the grain column height（h） and time（t）, and by using the relation we discuss the change of the growth velocity（ dh/ dt） and acceleration（ d^2h/ dt^2） with t and h, respectively. We also analyze the mechanism of the rising motion of the grains during vibration. Furthermore, we derive a theoretical expression for describing the final stable height（h st）, which shows that the main factors influencing the height are vibration strength（Γ）, bulk density of grains,inner diameter of the pipe, and vibration frequency, and that h st increases nonlinearly in the presence of air and linearly in a vacuum environment with increasing Γ.

关键词： granular matter vertical vibration theoretical analysis

Stall Evolution Mechanism of a Centrifugal Compressor with a Wide-Long Vaneless Diffuser

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Journal of Thermal Science 2024年第3期33卷 899-913页

作者： ZHANG Lei KANG Jiacheng LANG Jinhua AN Guangyao ZHANG Qian WANG Longyao WANG Qifang Department of power Engineering North China Electric Power UniversityBaoding071003China Hebei Key Laboratory of Low Carbon and High Efficiency power Generation Technology North China Electric Power UniversityBaoding071003China

The rotating stall mechanism is of high importance for the stability of centrifugal compressors and thermal power *** majority of research concerning this topic has concentrated on the initial stall ***,the evolution of stall cells in wide-long diffusers has not been comprehensively *** this paper,the causes of rotating stall in the wide-long diffuser and the three-dimensional evolution mechanism of stall cells during the stall process were thoroughly *** the stall induction phase,an annulus vortex structure was found in the reverse-flow zone near the hub side of the diffuser outlet,which was the initial form of stall *** whole evolution process of stall cells was divided into three phases as the flow rate *** the initial stall phase,the dynamic equilibrium was built under effects of the impeller wake and the adverse pressure *** a result,the number of stall cells was kept at seven and the size of stall cells remained *** the transition phase,the flow in the diffuser became *** cells extended to the impeller outlet,and the effect of the wake flow was strengthened *** cells started integrating and separating *** a result,the number and propagation speed of stall cells varied periodically at a constant mass flow *** the deep stall phase,the size of stall cells remained unchanged,and the number of stall cells kept at *** study has important practical guidance and engineering value for the high-efficiency design and safe operation of centrifugal compressors.

关键词： centrifugal compressor wide-long vaneless diffuser stall evolution mechanism wake flow

Resilient outage recovery of a distribution system: co-optimizing mobile power sources with network structure

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Protection and Control of Modern power Systems 2022年第1期7卷 459-471页

作者： Chenchen Li Yanna Xi Yufan Lu Nian Liu Liudong Chen Li Ju Yibin Tao State Key Laboratory of Alternate electrical power System with Renewable Energy Sources(north china electric power university) BeijingChina State Grid Beijing electric power Company BeijingChina china electric power research institute NanjingChina

Outage recovery is important for reducing the economic cost and improving the reliability of a distribution system(DS)in extreme weather and with equipment *** studies have separately considered network reconfigu-ration(NR)and dispatching mobile power sources(MPS)to restore the outage ***,NR cannot deal with the scenario of an electrical island,while dispatching MPS results in a long power *** this paper,a resilient outage recovery method based on co-optimizing MPS and NR is proposed,where the DS and traffic network(TN)are considered *** the DS,the switch action cost and power losses are minimized,and the access points of MPSs are changed by carrying out the NR *** the TN,an MPS dispatching model with the objective of mini-mizing power outage time,routing and power generation cost is developed to optimize the MPSs’schedule.A solu-tion algorithm based on iteration and relaxation methods is proposed to simplify the solving process and obtain the optimal recovery ***,numerical case studies on the IEEE 33 and 119-bus systems validate the proposed resilient outage recovery *** is shown that the access point of MPS can be changed by NR to decrease the power outage time and dispatching cost of *** results also show that the system operation cost can be reduced by considering power losses in the objective function.

关键词： Resilient outage recovery Network reconfiguration Mobile power sources Co-optimization Traffic network

Optimal Frequency Regulation Based on Characterizing the Air Conditioning Cluster by Online Deep Learning

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CSEE Journal of power and Energy Systems 2022年第5期8卷 1373-1387页

作者： Yeyan Xu Liangzhong Yao Siyang Liao Yaping Li Jian Xu Fan Cheng School of electrical Engineering and Automation Wuhan UniversityWuhan 430072China china electric power research institute Nanjing 210008China china electric power research institute Beijing 100085China

The air conditioning cluster(ACC)is a potential candidate to provide frequency regulation ***,the effective assessment of the ACC willing reserve capacity is often an obstacle for existing demand response(DR)programs,influenced by incentive prices,temperatures,*** this paper,the complex relationship between the ACC willing reserve capacity and its key influence factors is defined as a demand response characteristic(DRC).To learn about DRC along with real-time frequency regulation,an online deep learning-based DRC(ODLDRC)modeling methodology is designed to continuously retrain the deep neural network-based *** ODL-DRC model trained by incoming new data does not require massive historical training data,which makes it more ***,the coordinate operation between ODL-DRC modeling and optimal frequency regulation(OFR)is presented.A robust decentralized sliding mode controller(DSMC)is designed to manage the ACC response power in primary frequency regulation against any ACC response *** ODL-DRC model-based OFR scheme is formulated by taking the learning error into ***,the ODL-DRC model can be applied to minimize the total operational cost while maintaining frequency stability,without waiting for a well-trained *** simulation cases validate the superiority of the OFR based on characterizing the ACC by online learning,which can capture the real DRC and simultaneously optimize the regulation performance with strong robustness against any ACC response uncertainty and learning error.

关键词： Air conditioning demand response characteristic online deep learning optimal frequency regulation sliding mode control

Wind power prediction based on variational mode decomposition multi-frequency combinations

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Journal of Modern power Systems and Clean Energy 2019年第2期7卷 281-288页

作者： Gang ZHANG Hongchi LIU Jiangbin ZHANG Ye YAN Lei ZHANG Chen WU Xia HUA Yongqing WANG institute of Water Resources and Hydro-electric Engineering Xi’an University of TechnologyXi’an 710048China State Grid Gansu electric power Company Gansu Electric Power Research InstituteLanzhou 730050China State Grid Shaanxi electric power Company Shaanxi Electric Power Research InstituteXi’an 710054China

Because of the uncertainty and randomness of wind speed, wind power has characteristics such as nonlinearity and multiple frequencies. Accurate prediction of wind power is one effective means of improving wind power integration. Because the traditional single model cannot fully characterize the fluctuating characteristics of wind power, scholars have attempted to build other prediction models based on empirical mode decomposition(EMD) or ensemble empirical mode decomposition(EEMD) to tackle this problem. However, the prediction accuracy of these models is affected by modal aliasing and illusive components. Aimed at these defects, this paper proposes a multi-frequency combination prediction model based on variational mode decomposition(VMD). We use a back propagation neural network(BPNN),autoregressive moving average(ARMA)model, and least square support vector machine(LS-SVM) to predict high, intermediate,and low frequency components,respectively. Based on the predicted values of each component, the BPNN is applied to combine them into a final wind power prediction ***,the prediction performance of the single prediction models(ARMA,BPNN and LS-SVM)and the decomposition prediction models(EMD and EEMD) are used to compare with the proposed VMD model according to the evaluation indices such as average absolute error, mean square error,and root mean square error to validate its feasibility and accuracy. The results show that the prediction accuracy of the proposed VMD model is higher.

关键词： Wind power prediction Variational mode decomposition Multi-frequency combination prediction Back propagation neural network Autoregressive moving average model Least square support vector machine

High-frequency Resonance Analysis and Impedance Reshaping Control of MMC-HVDC System Based on Frequency Coupling Impedance Model

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Journal of Modern power Systems and Clean Energy 2024年第2期12卷 646-657页

作者： Juanjuan Wang Wei Chen Yuekun Liu Chuang Fu Yunming Ye Junjie Feng School of electric power South China University of TechnologyGuangzhouChina Guangdong power Grid Co. Ltd.GuangzhouChina electric power research institute China Southern Power GridGuangzhouChina

In recent years, high-frequency resonance (HFR) events occurred in several modular multilevel converter based high-voltage direct current (MMC-HVDC) projects. The time delay of an MMC-HVDC system is the critical factor that induces HFR. The frequency coupling affects the impedance characteristics of an MMC and further deteriorates system stability. Therefore, in this paper, a multi-input multi-output admittance model of an MMC-HVDC system is developed to analyze its frequency characteristics. The effects of current loop, power loop, phase-locked loop, and operating point on the MMC frequency coupling degree are analyzed in detail. Meanwhile, to further suppress HFR in the MMC-HVDC system, an enhanced impedance reshaping control strategy based on the equivalent single-input single-output impedance model is proposed. Finally, the accuracy of the enhanced impedance model and the effectiveness of the impedance reshaping control are verified by electromagnetic transient simulations in PSCAD.

关键词： Modular multilevel converter based high-voltage direct current(MMC-HVDC) high-frequency resonance frequency coupling impedance model impedance reshaping control

A Robust Superhydrophobic Smart Coating with Reversible Thermochromic and Photochromic Property

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Journal of Bionic Engineering 2022年第6期19卷 1589-1600页

作者： Peng Wang Xuesong Zhang Zhihao Wang Tao Chen Honglian Zhang Wei Duan Huilong Han School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBaoding071000China Hebei Key Laboratory of electric Machinery Health Maintenance and Failure Prevention North China Electric Power UniversityBaoding071003China

Both thermochromic and photochromic coating have attracted many attentions due to their widely applications,but the low stability is a big *** by the lotus leaf,to endow the chromic coating with superhydrophobicity is a possible *** this research,a dual response coating was prepared by adding photochromic and thermochromic particles *** prepared sample demonstrated at least four-state color switching,which can be successfully used in tactile imaging,multi-color fabric,erasable record,and security *** superhydrophobicity was achieved by introducing vinyl-terminated polydimethylsiloxane,which not only offers low surface energy but also can cross-link with the particles to increase the ***,the prepared sample maintained superhydrophobicity after various kinds of destruction(such as sandpaper abrasion,corrosive liquid attack,ultrasonic treatment,UV irradiation,and high-speed drops/turbulent jets impact).Even though the superhydrophobicity can be destroyed by plasma etching,it can be recovered after 12 h at room temperature.

关键词： Bionic coating Superhydrophobic Thermochromic Photochromic Robust

Thermodynamics of Cascaded Waste Heat Utilization from Flue Gas and Circulating Cooling Water

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Journal of Thermal Science 2023年第6期32卷 2166-2178页

作者： LI Yuanyuan CHEN Xin JIANG Shan LU Gui State Key Laboratory of New Energy power Systems North China Electric Power UniversityBeijing102206China Department of Water Resources China Institute of Water Resources and Hydropower ResearchBeijing100038China School of Energy power and Mechanical Engineering North China Electric Power UniversityBeijing102206China

A detailed thermal power plant model was developed to evaluate power plant waste heat usage in terms of the operating parameters,energy consumption,water consumption,and pollutant *** model was used to analyze the bypass flue gas energy cascade utilization design which provides excellent energy savings and emission *** paper then presents a design to use the low-temperature waste heat and to extract water from the flue *** low-grade heat can be recovered from a coal-fired unit using absorption heat pumps to increase the air *** method significantly reduces the turbine steam extraction in the low pressure stages which increases the turbine power and reduces the coal *** design has a small heat transfer temperature difference between the air preheater and the air warmer,resulting in a smaller exergy *** power output of the present design was 1024.28 MW with a coal consumption savings of 3.69 g·(kWh)^(−1).In addition,the present design extracts moisture out of the flue gas to produce 46.48 t·h^(−1)of *** main goal of this work is to provide a theoretical analysis for studying complex thermal power plant systems and various energy conservation and CO_(2)reduction options for conventional power plants.

关键词： integrated thermal power plant model low-grade waste heat energy cascade utilization exergy losses absorption heat pumps