Fan Y.,Nanjing Southeast University |
Fan Y.,Jiangsu Key Laboratory of Smart Grid Technology and Equipment |
Zhang L.,Nanjing Southeast University |
Huang J.,Wuhu Power Supply Company |
Han X.,Jiangsu Electrical Power Design Institute
IEEE Transactions on Industrial Electronics | Year: 2014
This paper is to propose a new self-decelerating permanent-magnet (PM) in-wheel motor for low-speed and high-torque drive of electric vehicles (EVs). This motor uses sensorless control and integrates advantages of magnetic gear and those of PM machine together while gear inner rotor is removed. The key is the magnetic gear, which can reduce the size of the motor and achieve the similar torque amplification provided by a mechanical gearbox and does not require maintenance or cause breakdown issues. The topology and the operating principle of the proposed in-wheel motor are analyzed; the effects of flux modulated by the magnetic gear and the static characteristics are investigated by using the finite-element analysis. To solve the problems of mechanical sensors, an improved sliding model observer for sensorless control is studied. Then, the evaluation of the system performances is conducted by the simulation based on the MATLAB/Simulink and the experiment based on a prototype. Both the simulation and the experimental results show that the system can provide low-speed high-torque driving for EVs without mechanical gears and sensors. © 1982-2012 IEEE.
Zong L.,Nanjing Southeast University |
Zong L.,Jiangsu Electrical Power Design Institute |
Li Y.,Nanjing Southeast University |
Wang B.,Nanjing Southeast University
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012
In view of the need of accurately grasping the characteristics of the user's requirement for power consumption in the process of the demand side management (DSM), these characteristics are finely mined with respect to the dimensions of time, genre and response. The power consumption characteristics are finely analyzed from multiple dimensions by combining the advantages of the system clustering and fuzzy clustering, introducing and improving the secondary clustering algorithm, with the corresponding load characteristic vectors extracted for the clustering analysis. The results show that the improved algorithm is simple and effective, and capable of mining more effective information for the demand side as well as selecting potential users appropriate for DSM. It will provide specific information, such as outage capacity, outage time, and assist to estimate risks and benefits for the DSM subject. © 2012 State Grid Electric Power Research Institute Press.
Zhu C.,Nanjing Southeast University |
Mei J.,Nanjing Southeast University |
Wang C.,Jiangsu Electrical Power Design Institute |
Zheng J.,Nanjing Southeast University
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2013
In intelligent substations, current digital sampled data are presented by electronic current transducers(ECTs) to the differential protection device. When the ECTs' sampling rates are not all the same, it is compelled to convert different sampling rates to the same one. In this paper, the concept of low-delay finite impulse response filter is presented. Furthermore, a low-pass filter for signal decimation and interpolation link cascade is designed based on the constrained least squares method, which has realized the fast response of any rational multiple rate conversion. A model of 500kV transformer system model is built for simulation analysis. Compared with the traditional low-pass filter based on the Chebyshev approximation principle, output data response of the designed filter is faster by 37.5%. And peak instantaneous error is controlled within 3.683%, which can effectively reduce the output delay and improve the operating speed of the differential protection.
Jia Y.,Xi'an Jiaotong University |
Zhao J.,Xi'an Jiaotong University |
Zhao J.,Jiangsu Electrical Power Design Institute |
Fu X.,Xi'an Jiaotong University
IEEE Transactions on Power Electronics | Year: 2014
A direct grid current control strategy for LCL-filtered grid-connected inverters is proposed in this paper. The conventional current control strategies are analyzed and compared, and then the necessity of direct grid current control is presented to mitigate the grid voltage disturbance. In the proposed control strategy, the virtual resistance based on the capacitance current is used to realize active damping, zero compensation is brought in to enhance the stability, and the proportional resonant (PR) controller under two-phase static coordinate is designed to track the ac reference current as well as to avoid the strong coupling brought by the coordinate transformation. Under the distortion grid voltage, the PR plus harmonic compensator (PR+HC) structure is adopted to restrain the distortion of the grid current. Finally, the proposed control strategy is verified by the experimental results. © 1986-2012 IEEE.
Lu D.,Jiangsu Electrical Power Design Institute |
Sun C.,Jiangsu Electrical Power Design Institute |
Wang X.,Jiangsu Electrical Power Design Institute
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2011
According to the requirements of smart substation for online monitoring, a technical scheme of online monitoring system on unified analysis platform based on IEC61850 is proposed, which standardizes the output of different data acquisition frontends. The input data of frontends are the unified as 4~20 mA standard signals or the acceptable signals of integrated smart components. The smart device model based on integrated smart component or composed of smart unit and online monitoring unit is established, which uploads the motoring information and control information separately. The frame of integrated online monitoring system based on IEC61850 standard for smart substation is designed.
Liu Y.-P.,Jiangsu Electrical Power Design Institute
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010
The support system composed of double arched beams and bored piles in foundation pits has many advantages, such as better whole stability, smaller displacement of pile top, larger excavation space, shorter construction period and lower cost, compared with other systems of large and deep foundation pits. A foundation pit of the building with a three-storeyed basement is taken as a study case. The problem of less construction space and complex surrounding environment is effectively solved. More economic benefits are obtained and the cost is further reduced by the application of local reinforcement and two piles united into one pile.
Jian B.,Chongqing University |
Wang G.-B.,Jiangsu Electrical Power Design Institute |
Xie X.,Chongqing University
Gongcheng Lixue/Engineering Mechanics | Year: 2014
Based on the analysis of the seismic performance of 16 partially prestressed concrete (PPC) frame structures designed according to China current codes, the quantitative index of PPC frame performance levels and the reliability of a design displacement in Direct Displacement-Based Design (DDBD) had been analyzed. After three performance levels of basic integrity, life safety and collapse prevention defined, crack width, bearing capacity had been suggested as a quantitative reference index and the corresponding interstory drift ratio as a final quantitative index. At the same time, taking the interstory drift ratio corresponding to a quantitative index as resistances and corresponding to expected earthquakes as effects, a simplified method had been put forward, in which reliability can be taken into account in DDBD and associated to the reliability level of current codes. In this method, the error arose from the coefficient of variation can be avoid greatly and different requirements can be satisfied under an identical performance level.
Huang J.,Jiangsu Electrical Power Design Institute |
Wang X.,Nanjing University of Aeronautics and Astronautics
Advanced Composites Letters | Year: 2011
Composite tubes with different cross-sectional shapes, including quarter circle, half circle and three-quarter circle, are axially crushed to study the boundary effects on the energy absorption of cylindrical shells and develop a semi-empirical analysis method for the crashworthy design of composite structures. It is observed experimentally that all specimens crush from the chamfered end and exhibit stable progressive crushing with similar macroscopic failure modes. Experimental results indicate that the load-displacement curves of all specimens are similar to those of full-circle tubes. And the quarter-circle tubes show the lowest energy absorption capability, while the half-circle tubes and three-quarter-circle tubes show almost the same energy absorption capability. It is found that quarter-circle thermoset tubes without and with one free edge provide 19% and 13% higher energy absorption capability than the quarter-circle thermoset tubes with two free edges; while quarter-circle thermoplastic tubes without and with one free edge provide 6% and 2% higher energy absorption capability than the quarter-circle thermoplastic tubes with two free edges, respectively. It is also found that the semi-empirical analysis method based on crush data and boundary effects of the quarter-circle tubes can accurately predict the energy absorption capability of half-circle or full-circle tubes.
Pan X.,Jiangsu Electrical Power Design Institute
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2012
It is necessary to describe the statistical properties of wind speed using three-parameter Weibull distribution for offshore wind energy resource assessment and utilization. According to the functional relation between parameters and probability-weighted moments (PWM), the functions were fitted with the shape parameter and PWM using logistic curve. Two formulae of parameter estimation were studied out based on low-order insufficient and exceeding PWM. Accuracy test results show that these formulae had higher precision in large-scale range. Through comparative analysis with high-order PWM method for example, the author believes the low-order PWM methods in this paper are worth popularizing. ©2012 Chinese Society for Electrical Engineering.
Huiming L.,North China Electrical Power University |
Zhao Z.,Jiangsu Electrical Power Design Institute
ICCASM 2010 - 2010 International Conference on Computer Application and System Modeling, Proceedings | Year: 2010
Real-Time Database is the result of the integration of traditional database technologies and real-time systems, and it's the core of the supervisory information system (SIS). It acts as an essential role in industrial fields and thus is very significant and valuable to research and practice. Historical data is regularly sampled from real-time database system and stored in history database. The user can access data from history database if necessary. Preservation of the historical data is a very important function of real-time database system. Historical data processing concerns the integrity of real-time database system. And the design of real-time database influences system performance. The historical data process in Real-Time Database is introduced in detail, and the implement action of disk history database is described. © 2010 IEEE.