Novel Model Predictive Control Method to Eliminate Common-mode Voltage for Three-level T-type Inverters Considering Dead-time Effects

Wang, Xiaodong,Zou, Jianxiao,Dong, Zhenhua,Xie, Chuan,Li, Kai,Guerrero, Josep M. The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.5

This paper proposes a novel common-mode voltage (CMV) elimination (CMV-EL) method based on model predictive control (MPC) to eliminate CMV for three-level T-type inverters (3LT2Is). In the proposed MPC method, only six medium and one zero voltage vectors (VVs) (6MV1Z) that generate zero CMV are considered as candidates to perform the MPC. Moreover, the influence of dead-time effects on the CMV of the MPC-based 6MV1Z method is investigated, and the candidate VVs are redesigned by pre-excluding the VVs that will cause CMV fluctuations during the dead time from 6MV1Z. Only three or five VVs are included to perform optimization in every control period, which can significantly reduce the computational complexity. Thus, a small control period can be implemented in the practical applications to achieve improved grid current performance. With the proposed CMV-EL method, the CMV of the $3LT^2Is$ can be effectively eliminated. In addition, the proposed CMV-EL method can balance the neutral point potentials (NPPs) and yield satisfactory performance for grid current tracking in steady and dynamic states. Simulation and experimental results are presented to verify the effectiveness of the proposed method.

Joint distribution of wind speed and direction in the context of field measurement

Wang, Hao,Tao, Tianyou,Wu, Teng,Mao, Jianxiao,Li, Aiqun Techno-Press 2015 Wind and Structures, An International Journal (WAS Vol.20 No.5

The joint distribution of wind speed and wind direction at a bridge site is vital to the estimation of the basic wind speed, and hence to the wind-induced vibration analysis of long-span bridges. Instead of the conventional way relying on the weather stations, this study proposed an alternate approach to obtain the original records of wind speed and the corresponding directions based on field measurement supported by the Structural Health Monitoring System (SHMS). Specifically, SHMS of Sutong Cable-stayed Bridge (SCB) is utilized to study the basic wind speed with directional information. Four anemometers are installed in the SHMS of SCB: upstream and downstream of the main deck center, top of the north and south tower respectively. Using the recorded wind data from SHMS, the joint distribution of wind speed and direction is investigated based on statistical methods, and then the basic wind speeds in 10-year and 100-year recurrence intervals at these four key positions are calculated. Analytical results verify the reliability of the recorded wind data from SHMS, and indicate that the joint probability model for the extreme wind speed at SCB site fits well with the Weibull model. It is shown that the calculated basic wind speed is reduced by considering the influence of wind direction. Compared to the design basic wind speed in the Specification of China, basic wind speed considering the influence of direction or not is much smaller, indicating a high safety coefficient in the design of SCB. The results obtained in this study can provide not only references for further wind-resistance research of SCB, but also improve the understanding of the safety coefficient for wind-resistance design of other engineering structures in the similar area.

Novel Model Predictive Control Method to Eliminate Common-mode Voltage for Three-level T-type Inverters Considering Dead-time Effects

Xiaodong Wang,Jianxiao Zou,Zhenhua Dong,Chuan Xie,Kai Li,Josep M. Guerrero 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.5

This paper proposes a novel common-mode voltage (CMV) elimination (CMV-EL) method based on model predictive control (MPC) to eliminate CMV for three-level T-type inverters (3LT²Is). In the proposed MPC method, only six medium and one zero voltage vectors (VVs) (6MV1Z) that generate zero CMV are considered as candidates to perform the MPC. Moreover, the influence of dead-time effects on the CMV of the MPC-based 6MV1Z method is investigated, and the candidate VVs are redesigned by pre-excluding the VVs that will cause CMV fluctuations during the dead time from 6MV1Z. Only three or five VVs are included to perform optimization in every control period, which can significantly reduce the computational complexity. Thus, a small control period can be implemented in the practical applications to achieve improved grid current performance. With the proposed CMV-EL method, the CMV of the 3LT²Is can be effectively eliminated. In addition, the proposed CMV-EL method can balance the neutral point potentials (NPPs) and yield satisfactory performance for grid current tracking in steady and dynamic states. Simulation and experimental results are presented to verify the effectiveness of the proposed method.

Numerical Analysis on Buffeting Performance of a Long-Span Four-Tower Suspension Bridge Using the FEM Model

Hao Wang,Zidong Xu,Min Yang,Tianyou Tao,Jianxiao Mao,Hui Gao 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.3

The multi-tower suspension bridge (MTSB), which is a considerable choice for the cross-river and even cross-sea bridges, has attracted intensive attentions by researchers in recent years. However, the static and dynamic performance of the MTSB becomes more complicated due to its super long spans and the multiple middle towers. The wind-induced vibration becomes the critical issue when constructs the MTSBs due to their low rigidity. In this work, a finite element model (FEM) of a MTSB with four towers and three spans is presented. Several major parameters such as the stiffness of the main girder and the middle towers, the sag-to-span ratios, the self-excited forces, and the spectral model of turbulence are selected to investigate their effects on buffeting performance of the MTSB. Results show that the rigid main girder can decrease the buffeting displacements in lateral and torsional directions, while the vertical buffeting displacement significantly decreases with the increasing stiffness of middle towers. In addition, the buffeting displacements of the main girder increase with the decreasing sag-to-span ratio. Besides, it can be concluded that the self-excited forces should be considered and the turbulent power spectrum should be carefully chosen in analyzing buffeting responses of the MTSB.

Joint distribution of wind speed and direction in the context of field measurement

Hao Wang,Tianyou Tao,Teng Wu,Jianxiao Mao,Aiqun Li 한국풍공학회 2015 Wind and Structures, An International Journal (WAS Vol.20 No.5

The joint distribution of wind speed and wind direction at a bridge site is vital to the estimation of the basic wind speed, and hence to the wind-induced vibration analysis of long-span bridges. Instead of the conventional way relying on the weather stations, this study proposed an alternate approach to obtain the original records of wind speed and the corresponding directions based on field measurement supported by the Structural Health Monitoring System (SHMS). Specifically, SHMS of Sutong Cable-stayed Bridge (SCB) is utilized to study the basic wind speed with directional information. Four anemometers are installed in the SHMS of SCB: upstream and downstream of the main deck center, top of the north and south tower respectively. Using the recorded wind data from SHMS, the joint distribution of wind speed and direction is investigated based on statistical methods, and then the basic wind speeds in 10-year and 100-year recurrence intervals at these four key positions are calculated. Analytical results verify the reliability of the recorded wind data from SHMS, and indicate that the joint probability model for the extreme wind speed at SCB site fits well with the Weibull model. It is shown that the calculated basic wind speed is reduced by considering the influence of wind direction. Compared to the design basic wind speed in the Specification of China, basic wind speed considering the influence of direction or not is much smaller, indicating a high safety coefficient in the design of SCB. The results obtained in this study can provide not only references for further wind-resistance research of SCB, but also improve the understanding of the safety coefficient for wind-resistance design of other engineering structures in the similar area.

Identification of moving train loads on railway bridge based on strain monitoring

Hao Wang,Qingxin Zhu,Jian Li,Jianxiao Mao,Suoting Hu,Xinxin Zhao 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.23 No.3

Moving train load parameters, including train speed, axle spacing, gross train weight and axle weights, are identified based on strain-monitoring data. In this paper, according to influence line theory, the classic moving force identification method is enhanced to handle time-varying velocity of the train. First, the moments that the axles move through a set of fixed points are identified from a series of pulses extracted from the second derivative of the structural strain response. Subsequently, the train speed and axle spacing are identified. In addition, based on the fact that the integral area of the structural strain response is a constant under a unit force at a unit speed, the gross train weight can be obtained from the integral area of the measured strain response. Meanwhile, the corrected second derivative peak values, in which the effect of time-varying velocity is eliminated, are selected to distribute the gross train weight. Hence the axle weights could be identified. Afterwards, numerical simulations are employed to verify the proposed method and investigate the effect of the sampling frequency on the identification accuracy. Eventually, the method is verified using the real-time strain data of a continuous steel truss railway bridge. Results show that train speed, axle spacing and gross train weight can be accurately identified in the time domain. However, only the approximate values of the axle weights could be obtained with the updated method. The identified results can provide reliable reference for determining fatigue deterioration and predicting the remaining service life of railway bridges.

Wind characteristics at Sutong Bridge site using 8-year field measurement data

Xu, Zidong,Wang, Hao,Wu, Teng,Tao, Tianyou,Mao, Jianxiao Techno-Press 2017 Wind and Structures, An International Journal (WAS Vol.25 No.2

Full-scale wind characteristics based on the field measurements is an essential element in structural wind engineering. Statistical analysis of the wind characteristics at Sutong Cable-stayed Bridge (SCB) site is conducted in this study with the recorded long-term wind data from structural health monitoring system (SHMS) between 2008 and 2015. Both the mean and turbulent wind characteristics and power spectra are comprehensively investigated and compared with those in the current codes of practice, such as the measured wind rose diagram, monthly maximum mean wind speed, turbulence intensity, integral length scale. Measurement results based on the monitoring data show that winds surrounding the SCB site are substantially influenced by the southeast monsoon in summer and strong northern wind in winter. The measured turbulence intensity is slightly higher than the recommended values in specifications, while the measured ratio of lateral to longitudinal turbulence intensity is slightly lower. An approximately linear relationship between the measured turbulence intensities and gust factors is obtained. The mean value of the turbulence integral length scale is smaller than that of typical typhoon events. In addition, it is found that the Kaimal spectrum is suitable to be adopted as the power spectrum for longitudinal wind component at the SCB site. This contribution would provide important wind characteristic references for the wind performance evaluation of SCB and other civil infrastructures in adjacent regions.

Multi-cue Integration Object Tracking Based on Blocking

Lichuan Gu,Chengji Wang,Jinqin zhong,Jianxiao Liu,Juan Wang 보안공학연구지원센터 2014 International Journal of Security and Its Applicat Vol.8 No.3

Economic Optimization Operation Approach of Integrated Energy System Considering Wind Power Consumption and Flexible Load Regulation

Meng Qinglin,Xu Jing,Ge Leijiao,Wang Zhongguan,Wang Jianxiao,Xu Liang,Tang Zhipeng 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1

Due to the fuctuation of wind power output and the "heat to power" mode in the heating period, the wind abandonment phenomenon in coastal areas in winter is increasingly serious. From the perspective of integrated energy system in coastal areas, this paper frst builds an optimal operation model of integrated energy system in coastal areas with the minimum daily total operating cost and the minimum amount of abandoned wind, and constrains the output condition of the corresponding equipment. Then, the mechanism of the adjustable characteristics of seawater desalination load is analyzed, the adjustment range of seawater desalination load is calculated, and the integrated energy system optimization operation method in coastal areas is designed considering the desalination load. Finally, the winter scene of a coastal area in northern China is taken as an example to conduct simulation verifcation. The results show that the total daily operation cost of the system is reduced by 4.6% and the wind power consumption rate is increased by 2.87% after considering the load regulation efect of seawater desalination, which efectively verifes that the integrated energy system operation strategy designed plays a signifcant role in improving the system operation economy and promoting the consumption of new energy.

Polyacrylonitrile fiber with strongly acidic electrostatic microenvironment: Highly efficient and recyclable heterogeneous catalyst for the synthesis of heterocyclic compounds

Jian Xiao,Gang Xu,Lu Wang,Pengyu Li,Wenqin Zhang,Ning Ma,Minli Tao 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.77 No.-

Four categories of sulfonic acid functionalizedfiber catalysts with different surface microenvironmentswere synthesized by covalent grafting using polyacrylonitrilefiber (PANF) as the support. After the effectof acid structure on catalytic activity has been investigated by Friedlander reaction, PANEOSF was chosenfor the synthesis of quinolines and coumarin derivatives with high yields and extensive substrate scope(51 examples) in ethanol or water. The effect of electrostatic microenvironment and solvent has beendiscussed, and a “release-catch-release-catch” catalytic pattern was proposed accordingly. PANEOSF canbe easily recycled for 20 times without any decrease of catalytic activity.