Xue G.,Shanghai JiaoTong University |
Zhang Y.,Shanghai JiaoTong University |
Zhu D.,Shanghai Municipal Electric Power Company
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2013
A low-voltage unipolar-type DC microgrid composed of PVA(PhotoVoltaic Array), FC(Fuel Cell) and SC(Super-Capacitor) is studied and its operational control strategy considering the characteristics of DGs is researched. The open-circuit-voltage proportional-coefficient method is used to track the maximum power of PVA. The slope limiter is employed to limit the rate of FC power change for preventing the fuel starvation and improving its performance and lifetime. The sliding mode control is applied to SC for its rapid charging and discharging to stabilize the DC bus voltage. A system model is established with MATLAB/Simulink and the simulative results show that, the proposed control strategy increases the energy utilization efficiency and improves the power quality of system.
Xing L.,Shanghai JiaoTong University |
Zhang P.,Shanghai JiaoTong University |
Fang C.,Shanghai Municipal Electric Power Company |
Zhang Y.,Shanghai Municipal Electric Power Company
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2013
With the development of smart grid technology, it is now more convenient for the implementation of demand-side response and the integration of all kinds of distributed energy resources. This paper first analyses the respective functions and coordination relationships of distributed generation, load and energy storage in the microgrid optimal operation, and regards them as the generalized demand side resources, then a more flexible optimization framework based on the concept of "source-load-storage" is built up. In order to reduce the dimensions of the optimal operation problem, this paper then puts forward a solving model which combines the heuristic rules and particle swarm algorithm. The heuristic rules are used to generate the optimal strategies for storages and loads, while the multiple-objective PSO is employed to optimize the power resources. To achieve both stability and accuracy in the optimal control, the receding horizon optimization technology is adopted. Finally, the simulation cases with different combinations of various demand side resources taken into account are presented, showing the effectiveness of the method proposed. © 2013 State Grid Electric Power Research Institute Press.
Zhu Z.,Shanghai Municipal Electric Power Company |
Gu Z.,Shanghai Municipal Electric Power Company |
Wu J.,Shanghai Municipal Electric Power Company |
Gui S.,State Grid Electric Power Research Institute of China
Dianwang Jishu/Power System Technology | Year: 2012
In allusion to low resource utilization of power system data recovery center and complex flow of data recovery business, a concrete thinking of leading cloud computing into data recovery is proposed. The feasibility and necessity of applying cloud computing in power system application is discussed, and a cloud computing resource management platform (CCRMP) is designed and implemented. The architecture of CCRMP and corresponding key technologies are researched, and the economic and management benefits brought by CCRMP are analyzed. By means of virtualization of server and storage, resource consolidation and modeling, resources allocation engine and so on, the heterogeneous resource consolidation on CCRMP, resource allocation on demand, dynamic online resource allocation, dynamic migration of application and workflow management is implemented. Combining with mirror technology of virtual machine CCRMP can back up the verification environment for the rapid deployment and data validation in the future. At present, CCRMP is practically applied in power system data recovery center and the problems to be faced with in the center are solved, and CCRMP makes data recovery business turning from original manual operation mode into standardized and automatic mode with IT support.
Liu J.-T.,China Electric Power Research Institute |
Wang Z.-H.,Shanghai Municipal Electric Power Company |
Wang K.,China Electric Power Research Institute
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013
Two-level voltage source converter (2Level-VSC) with IGBTs directly in series and modular multi-level converter (MMC) are two kinds of the most mainstream converters used in flexible HVDC. Their external features are similar; however, their characteristics of loss are different, which affects their economy and applicable workplace. Based on the device parameters provided by the manufacturer, a general loss calculation model is proposed which is applicable to calculating the losses of both the converters. Through analyzing the working status of devices of the two kinds of converters, loss calculation methods of the two are analyzed in detail. Finally, loss characteristics of 2Level-VSC and MMC are analyzed quantitatively through examples. The results show that loss characteristics of the two kinds of converters are different, and the efficiency of MMC is higher than that of the 2Level-VSC with IGBTs directly in series under different conditions.
Gan Z.,Shanghai Municipal Electric Power Company |
Li Z.-T.,Huazhong University of Science and Technology
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011
The islanding operation of distribution generation possibly does harm to the power system, customers and maintenance staffs. Therefore, the operating state of the distributed generation should be monitored appropriately. If the DG is islanded, the islanding must be detected quickly and the DG should be isolated from the main grid. Based on the conventional passive islanding detection methods, of which the typical ones are ROCOF and VS, a novel islanding detection method is proposed based on the advantages of ROCOF and VS and by means of appropriate coordination and setting of the existing ROCOF and VS methods. By virtue of PSCAD/EMTDC, a power system model including DG and integrating into the main grid is set up. A variety of power shortage conditions are simulated and the proposed scheme is verified. Test results demonstrate that this scheme is valid to detect the islanding. Furthermore, the correctness and reliability of the proposed method in various extreme condition are analyzed.
Li X.,Shanghai Municipal Electric Power Company |
Da F.,Nanjing Automation Research Institute
Image and Vision Computing | Year: 2012
This paper presents an efficient 3D face recognition method to handle facial expression and hair occlusion. The proposed method uses facial curves to form a rejection classifier and produce a facial deformation mapping and then adaptively selects regions for matching. When a new 3D face with an arbitrary pose and expression is queried, the pose is normalized based on the automatically detected nose tip and the principal component analysis (PCA) follows. Then, the facial curve in the nose region is extracted and used to form the rejection classifier which quickly eliminates dissimilar faces in the gallery for efficient recognition. Next, six facial regions which cover the face are segmented and curves in these regions are used to map facial deformation. Regions used for matching are automatically selected based on the deformation mapping. In the end, results of all the matching engines are fused by weighted sum rule. The approach is applied on the FRGC v2.0 dataset and a verification rate of 96.0% for ROC III is achieved as a false acceptance rate (FAR) of 0.1%. In the identification scenario, a rank-one accuracy of 97.8% is achieved. © 2012 Elsevier B.V.
Ming Y.,Shanghai Municipal Electric Power Company
2010 China International Conference on Electricity Distribution, CICED 2010 | Year: 2010
With the wide spread of HV switch cabinet in the electric system, how to effectively monitor the insulation inside the cabinet to avoid the fault is an important subject which all technicians are confronted with. The principle of the TEV measurement and its application in electric system are introduced to demonstrate the effectiveness of this method in the online test of partial discharge in the HV switch cabinet with the real case. © 2010 Chinese Soc for Elec Eng.
Wu K.,North China Electrical Power University |
Zhou H.,North China Electrical Power University |
An S.,North China Electrical Power University |
Huang T.,Shanghai Municipal Electric Power Company
Energy Conversion and Management | Year: 2015
An optimal coordinate operation control method for large-scale wind-photovoltaic (PV)-battery storage power generation units (WPB-PGUs) connected to a power grid with rated power output was proposed to address the challenges of poor stability, lack of decision-making, and low economic benefits. The "rainflow" calculation method was adopted to establish the battery cycle life model and to calculate quantitatively the life expectancy loss in the operation process. To minimize unit cost of power generation, this work optimized the output period of the equipment and strategy of battery charging and discharging with consideration of working conditions, generation equipment characteristics, and load demand by using the enhanced gravitational search algorithm (EGSA). A case study was conducted on the basis of data obtained using WPB-PGU in Zhangbei, China. Results showed that the proposed method could effectively minimize the unit cost of a WPB-PGU under different scenarios and diverse meteorological conditions. The proposed algorithm has high calculation accuracy and fast convergence speed. © 2014 Elsevier Ltd. All rights reserved.
East China University of Science, Technology and Shanghai Municipal Electric Power Company | Date: 2014-09-25
Disclosed is a method of measurement and determination on fracture toughness of structural materials at high temperature, comprising: preliminary assessing the ductility of a material based on a high-temperature uniaxial tensile test and the fracture characteristic; designing and manufacturing a CT specimen; conducting a monotonic loading fracture test on the CT specimen at high temperature; modifying a load-displacement curve output by a testing machine; determining a passivation coefficient M for the crack of the structural material; reversely recursing instant load-displacement data pairs corresponding to the instant crack length; calculating a J_R crack extension resistance curve of the tensile test; examining the validity of the J_R crack extension resistance curve and the fracture toughness J_(IC); calculating the fracture toughness per equivalent of the structural material K_(IC). The present invention overcomes the difficulty of placing an extensometer inside a high-temperature furnace.
State Grid Electrical Power Institute, Nanjing Nanrui Group and Shanghai Municipal Electric Power Company | Date: 2012-09-27
An equipment overload successive approximation adaptive control method based on centralized real-time decisions is provided. The method estimates in real time permissible current for long-term running of equipment and continuous running time according to current and temperature actual measurement information of the equipment. Control modes are decided according to the continuous running time of the equipment instead of current. On the basis of mixed integer nonlinear programming algorithm, a target function which aims to control the total cost and minimize comprehensive indexes of proportions of load control quantities of different regions is adopted, discreteness and cost of a control measure are taken into consideration, flow restraint of an electric system is measured, a centralized optimization decision and successive approximation control strategy are adopted, coordination to real-time scheduling operation control and emergency control for overload of equipment of the electric system is realized.