Experimental Study on Frequency Support of Variable Speed Wind Turbine Based on Electromagnetic Coupler

You, Rui,Chai, Jianyun,Sun, Xudong,Bi, Daqiang,Wu, Xinzhen The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1

In the variable speed Wind Turbine based on ElectroMagnetic Coupler (WT-EMC), a synchronous generator is coupled directly to the grid. Therefore, like conventional power plants, WT-EMC is able to inherently support grid frequency. However, due to the reduced inertia of the synchronous generator, WT-EMC is expected to be controlled to increase its output power in response to a grid frequency drop to support grid frequency. Similar to the grid frequency support control of Type 3 or Type 4 wind turbine, inertial control and droop control can be used to calculate the WT-EMC additional output power reference according to the synchronous generator speed. In this paper, an experimental platform is built to study the grid frequency support from WT-EMC with inertial control and droop control. Two synchronous generators, driven by two induction motors controlled by two converters, are used to emulate the synchronous generators in conventional power plants and in WT-EMCs respectively. The effectiveness of the grid frequency support from WT-EMC with inertial control and droop control responding to a grid frequency drop is validated by experimental results. The selection of the grid frequency support controller and its gain for WT-EMC is analyzed briefly.

A reliability assessment model for journal bearing based on natural degradation and random shocks

Yourui Tao,Jun Zhao,Shizhe Feng 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.11

In actual working conditions, journal bearing often suffers from natural degradation such as corrosion, wear, etc., and random shocks from the external environment. It is a problem of competitive failure of journal bearing caused by natural degradation and random shocks. A competition failure model with random shock is established. First, a degradation experimented system consisting of journal bearing bench, electromagnetic vibration bench and data acquisition was constructed. Then a reliability assessment model of journal bearing is established, the effect of external shocks is taken into the model. Finally, the element concentration of journal bearing lubrication is used as characteristic quantity. The analytical expression of journal bearing reliability is derived. The results showed that the proposed reliability model can accurately describe the wear process of bearing. The influence of impact strength on reliability is analyzed. The bearing is more likely to fail with the increase of impact strength. The extension proposed can be effectively applied to condition monitoring and reliability evaluation of journal bearing in the paper.

The multi-objective optimization design for the magnetic adsorption unit of wall-climbing robot

Zhihao Zhao,Yourui Tao,Jia Wang,Junyu Hu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.1

The motion stability and mass of the magnetic crawler wall-climbing robot usually affects the working performance of robot. In this study, the structure of the magnetic adsorption unit (MAU) is optimized based on the virtual prototyping technology to improve the working performance of robot. Firstly, the dynamic simulation model of the robot considering magnetic variation is established, and the model is verified by experiments. Based on the model, the objective function of the optimization model is established by DOE and surrogate model method. Then, through the force analysis of the robot, the minimum adsorption force required by each MAU is obtained, which is used as the constraint condition of the optimization model. Finally, the NSGA-II is used to solve the optimization model, and the results show that the vibration amplitude is reduced by 6.49 %, and the mass of the MAU is reduced by 9.66 %.

Kinematic response of industrial robot with uncertain-but-bounded parameters using interval analysis method

Jinhui Wu,Xu Han,Yourui Tao 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.1

The uncertain parameters of the deviation in link dimensions and joint clearances caused by manufacturing and assembling errors have a strong impact on the degree of accuracy of the industrial robot. Understanding how these uncertain parameters influence the kinematic response of the industrial robot is critical for design. In this paper, the interval method is used for analysing the kinematic response of the industrial robot with uncertain-but-bounded parameters. The interval used for describing the uncertain parameters is estimated by the grayscale theory. The Denavit-Hartenberg (D-H) method is used for establishing the kinematic model of a 6-degree-of-freedom industrial robot. The kinematic response of the industrial robot calculated by the interval method with uncertain parameters is compared with the results obtained by the probabilistic approach. The comparison results show that the upper or lower bound obtained by interval method is far away from the ideal kinematic response than that obtained by the probabilistic approach. That is a true portrayal of the essence of interval method and probabilistic approach. The research contributes to choose the tolerance zone of uncertain parameters, such as the link dimensions and joint clearances, during the design process of industrial robots.

Performance Degradation Model and Reliability Evaluation of Brush DC Motor for the Intelligent on–Off Valve

Yang Tianhao,Li Shanhu,Duan Shuyong,Tao Yourui,Han Xu 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.3

Application of the intelligent on–off valve reduces heat loss. As the critical control component of the intelligent on–off valve, the health state of the brush DC motor directly impacts whether the intelligent on–off valve can perform the regular operation. Therefore, the reliability evaluation of the brush DC motor is of great significance to the whole heat supply network. In this study, the failure mechanism of the brush DC motor is analyzed, and the absolute value of steady-state current variation is taken as the performance degradation characteristic parameter. According to the performance degradation characteristic parameter, the performance degradation model based on the Wiener process is established, and the inverse power rate acceleration model is introduced into the Wiener process to derive the reliability function of the motor. Based on the actual operating conditions that the motor in the intelligent on–off valve needs to start and stop frequently, an accelerated life test based on start-stop is designed. The error analysis result shows that the error between the expected start-stop times predicted by the proposed and the actual average failure start-stop times is only 2.14%. The proposed degradation model is more accurate than the motor's traditional performance degradation model.

Lycium barbarum Polysaccharide Inhibits Lipid Oxidation and Protein Degradation in Tan Sheep Meatballs during Frozen Storage

Jiangyong Yu,Mei Guo,Guishan Liu,Jingjing Zhang,Naiyun Fan,Xiaorui Li,Yourui Sun,Jiangtao Yuan,Rui Huang 한국축산식품학회 2022 한국축산식품학회지 Vol.42 No.4

The aim of the present study was to evaluate the effectiveness of Lycium barbarum polysaccharide (LBP) on lipid oxidation and protein degradation in Tan sheep meatballs during the frozen period. The meatballs were treated with LBP at 0.01%, 0.02%, and 0.03% and stored at –18±1℃ for 0, 3, 6, 9, and 12 weeks. The effects of LBP treatment were investigated using the contents of total volatile basic nitrogen (TVB-N), texture profile (TP), thiobarbituric acid reactive substances (TBARS), colour, and pH values, compared with 0.02% butylated hydroxytoluene treatment and the blank control. The results showed that LBP treatment significantly decreased TBARS content compared with the control, which confirmed LBP to be a highly effective component in preventing lipid oxidation of Tan sheep meatballs during frozen storage, and protein degradation in Tan sheep meatballs had a significant inhibition effect because of TVB-N value reduction. In addition, the colour, TP and pH values of meatballs treated with LBP were improved dramatically. To further determine the quality changes of the blank control and all treated groups during storage, the comprehensive score evaluation equation based on principal component analysis was obtained: Y=0.51632Y1+0.29589Y2 (cumulative contribution rate=81.221%), and the 0.02% LBP-treated group had a higher comprehensive score than the other groups, and the quality of LBP-treated meatballs was better as well. In summary, LBP may reduce or inhibit lipid oxidation and protein degradation, and enhance overall quality and shelf-life in prepared meat products.

A Feeder Impedance Identification Based Droop Control Method for Accurate Reactive Power Sharing in Islanded Microgrids

Jianyong Zhao,Jian Li,Heng Nian,Lei Yang,Bao Gai,Zaiping Pan,Yourui Xu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

Due to the unmatched feeder impedance, the conventional voltage and frequency droop control method is unable to accurately allocate the output reactive power of DG units in proportion to their power ratings. To solve this issue, this paper has proposed a feeder impedance identification based droop control method. Firstly, the relationship among the reactive power sharing, reactive power droop slope and feeder impedance in islanded microgrids is illustrated. An online feeder impedance identification method is subsequently adopted to modify the reactive power droop slope of DG unit. In this way, the effect of unmatched feeder impedance on reactive power sharing is eliminated without communication among DG units. Experimental results implemented on an islanded microgrid apparatus have validated the feasibility of the proposed droop control method.