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Li Q.,Guangdong Power Dispatching Center | Qian F.,NARI Group | Gu Q.,NARI Group
Dianwang Jishu/Power System Technology | Year: 2010

In general, power system dispatching adopts partitioned network monitoring mode and detailed power network models are built only for dispatching systems at different levels, and the rest part of power network external to the monitored part is represented by equivalent network, so there is obvious discrepancy between the equivalent mode and actual rest part. To meet the demand of different power network application and analysis systems, a power grid model integrated service system is designed, which not only possesses three core function modules, i. e., model splicing, measurement merging and graphic display, but also the application functions such as custom-made model, transient model matching and applied analysis of power network are extended, in addition, a unified Web service interface for the third party system is provided. Practical application shows that the designed system can meet the requirements for power network models and data from various power application systems.

Li Q.,Guangdong Power Dispatching Center | Xiang F.,Chongqing University | Yan W.,Chongqing University | Lu J.,Guangdong Power Dispatching Center | And 3 more authors.
Dianwang Jishu/Power System Technology | Year: 2011

Based on multi-interval information measured by phasor measurement units (PMU) and supervisory control and data acquisition (SCADA) system located at both sides of a single transmission line, five least squares constraints optimization models for parameter estimation of single transmission line are built, in which the measurement equations are composed of following measurements: the active power, reactive power and votlage amplitude are measured by SCADA at both sides of transmission line; the phasors of votlage and current are measured by PMUs; and the phase differences of voltage and current between both sides of transmission line are virtually measured by PMUs. The constraint equationa are composed of upper and lower physical constraints of parameter variables. The parameter estimation is solved by lsqnonlin optimization function in Matlab. Based on simulated measurement information of multi typical transmission lines the applicable conditions of all built models are simulated. Simulation results show that the impedance parameters of transmission line can be effectively estimated by four of the built models, which contains PMU measurement, under heavier load and longer length of transmission line.

Guo W.,South China University of Technology | Wen F.,Zhejiang University | Ledwich G.,Queensland University of Technology | Liao Z.,South China University of Technology | And 2 more authors.
IEEE Transactions on Power Delivery | Year: 2010

When a fault occurs on a section or a component in a given power system, if one or more protective relays (PRs) and/or circuit breakers (CBs) associated do not work properly, or in other words, a malfunction or malfunctions happen with these PRs and/or CBs, the outage area could be extended. As a result, the complexity of the fault diagnosis could be greatly increased. The existing analytic models for power system fault diagnosis do not systematically address the possible malfunctions of PRs and/or CBs, and hence may lead to incorrect diagnosis results if such malfunctions do occur. Given this background, based on the existing analytic models, an effort is made to develop a new analytic model to well take into account of the possible malfunctions of PRs and/or CBs, and further to improve the accuracy of fault diagnosis results. The developed model does not only estimate the faulted section(s), but also identify the malfunctioned PRs and/or CBs as well as the missing and/or false alarms. A software system is developed for practical applications, and realistic fault scenarios from an actual power system are served for demonstrating the correctness of the presented model and the efficiency of the developed software system. © 2010 IEEE.

Gao Y.,Tsinghua University | Wen B.,Guangdong Power Dispatching Center | Wu W.,Tsinghua University | Li Q.,Guangdong Power Dispatching Center | And 2 more authors.
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2012

The status of grid EMS (Energy Management System) research is summarized and the requirements of smart grid for EMS are analyzed, based on which, a N-EMS( New generation of EMS) with SOA (Service-Oriented Architecture) is proposed. Three application functions on its unified support platform are introduced: real-time dispatch control, dispatch planning and dispatch management, and its key technologies are discussed: multi-Agent based federated architecture, real-time modeling, whole-process gradient forewarning and preventive control, wide-range coordinative and unified dispatch, multi-time-scale coordinative active power dispatch, and multi-layer functional service configuration.

Yang Y.,South China University of Technology | Wen F.,Zhejiang University | Li L.,Guangdong Power Dispatching Center | Wang K.,Guangdong Power Dispatching Center | Gao C.,Guangdong Power Dispatching Center
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

Aiming at the problem to calculate available transfer capability (ATC) of power system with high wind power capacity, reasonably account for the risks associated with wind generation, two risk-controlling strategies, including specifying the smallest acceptable probability for power flow limits not violated and the total generation purchasing cost limit not violated, are introduced into the ATC calculation for enhancing the ability of the obtained ATC scheme against security and economic risks. First, an optimal power flow based chance constrained programming model, with security and economic risk control strategies taken into account, is developed. Next, the security and economic risks associated with the power flow limit and generation cost limit violations respectively are evaluated by the combined use of cumulants and Gram-Charlier series. Finally, the multi-objective differential evolution algorithm is employed for solving the developed optimization model. The IEEE 118-bus system is served for demonstrating the essential features of the developed model and method. © 2012 State Grid Electric Power Research Institute Press.

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