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Zhao J.-Q.,State Grid Corporation of China | Ding H.-E.,State Grid Corporation of China | Qian K.,State Grid Corporation of China | Li H.-Q.,Jiangsu Electric Power Company | And 4 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2014

In order to promote the development of smart and lean dispatching, the new smart control center constantly introducing es new technology to deal with the challengeThis paper analyzed technical characteristics of data system and major challenges facing smart control centers. The paper also systematically introduced introduces the concept of time stamped measurements for steady state grid and then proposed proposes a key technical scheme for application of time stamped measurements for smart control centers. Finally, some key technologies including unified application support platform integrated with time sequence database, supervisory control and data acquisition (SCADA) supported by time stamped measurements, state estimation based on time stamped measurements and open data platform based on time sequence database of the scheme are studied. The research result has been applied in pilot projects of smart grid dispatching technology support system in Suzhou City and Jiangsu Province, respectively. Source


Gong F.-X.,Nanjing Southeast University | Gong F.-X.,China Realtime Database Co. | Wang Q.,Nanjing Southeast University | Zhang X.-G.,Nanjing Southeast University
Zhongguo Guanxing Jishu Xuebao/Journal of Chinese Inertial Technology | Year: 2011

A hybrid GPS/TDOA(time difference of arrival algorithm)is proposed to realize location when neither GPS nor TDOA location method has positioning ability. The algorithm first makes differential operation between GPS pseudo-range equations to eliminate the constant terminal clock bias and gets GPS hyperbola equations. Then the GPS hyperbola equations are combined with TDOA hyperbola equations from cellular networks. The equations are then linearized by Taylor Series method, and the terminal location is iteratively estimated with least squares algorithm based on the linear equations. Field experiments show that more GPS pseudo-ranges will improve the location accuracy, but more TDOA measurements will degrade the location accuracy because of the big NLOS error in TDOA. It is concluded that GPS pseudo-ranges need be fully used when implementing the proposed algorithm, and TDOA measurements should be less used after ensuring location determined. In the experiments, the maximal error is 231.52 m and the root mean squared error under the best condition is 33.80 m. Such accuracy can satisfy the location applications when the precision requirement is not high but position information is indeed needed. Source


Zhao J.-Q.,Suzhou Power Supply Company | Ji S.-P.,China Realtime Database Co. | Qian K.-J.,Suzhou Power Supply Company | Zhou Y.-Z.,Suzhou Power Supply Company | And 4 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

This paper proposes a system to detect power system events based on relational database in power dispatching automation system and real-time database. With the developed models, the system sharply detects and analyzes abnormal grid events, such as switch trip and shock load. The real-time data is taken into consideration while doing analysis, which makes results more accurate. Taking the tripping of circuit breaker as an example, the process of fast detection of the power grid events is analyzed in detail. The proposed system has been successfully applied in the support system of smart dispatch for power systems in Suzhou. Test results show that the proposed system is able to reduce the working load of operators and can therefore provide a comprehensive protection for the secure operation of power systems. Operation records also show that the developed functions of the system have been running smoothly and can meet the requirements of power system automation of large-scale regional power systems. Source


Gong F.,Nanjing Southeast University | Gong F.,China Realtime Database Co. | Wang Q.,Nanjing Southeast University | Zhang X.,Nanjing Southeast University
Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument | Year: 2011

Under certain bad conditions, the number of observed GPS satellites is less than 4 for location determination and TDOA location method in cellular networks can not get enough TDOA measurements to position the mobile. In this paper, steepest decent method is used to fuse GPS pseudo-range and TDOA observations and resolve the problem; and the method can calculate the location even when neither of the two methods has positioning ability. The algorithm first differentiates between GPS pseudo-range equations to eliminate the constant terminal clock bias and gets GPS hyperbola equations. Then the GPS hyperbola equations are combined with TDOA hyperbola equations from cellular networks to define the weighted residual objective function. The optimal solution of the objective function is obtained with steepest decent method. The proposed algorithm is compared with Taylor-least squares hybrid location algorithm in field experiments. Results show that under the same condition, the proposed hybrid algorithm can achieve higher accuracy. The algorithm can perform better with more observations of GPS pseudo-range and TDOA. With 3 GPS pseudo-ranges and 3 TDOA, using the steepest decent hybrid algorithm, the average error is 17.64 m, which meets the requirements of general navigation systems. Source


Patent
State Grid Corporation of China, Jiangsu Electric Power Company, China Realtime Database Co. and State Grid Suzhou Power Supply Company | Date: 2013-10-21

A method and an apparatus for splitting and recovering data in a power system are provided in the invention. The method includes the steps of setting a first database and a data recovery unit in a platform layer of the power system. The first database runs in a memory of the power system and is composed of the real-time image in the memory of a grid model and static parameters of a second database. The first database is used to provide the inquiry service of the grid model and static parameters for the power system. The data recovery unit is responsible for all of the associated read-write operations with the second database. After data are written into, the data recovery unit stores the data as historical data according to the time scale characters, and writes the historical data to the second database when the second database is normal.

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