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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.


Li B.,State Grid Electric Power Research Institute of China | Wen B.,Guangdong Power Dispatching Center | Xu T.,State Grid Electric Power Research Institute of China | Yu Z.,Guangdong Power Dispatching Center | And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2011

Provincial and district grids are two important levels of grid in China's dispatching system. Higher requirements are made on the coordination of security and stability defense between the provincial and district grids. By referring to the actual need of grid operation and trend of grid development, a discussion is made on the general objective, item by item objectives for the coordination between provincial and district grids, the coordination between the two levels of grid, the coordination in all stages, and the three essentials for coordination. A coordinated defense framework for secure and stable operation is proposed. The development of the online comprehensive defense system for the integration of the provincial and district grids is tackled. The framework is of great significance for deepening understanding on the requirement of the coordination technology and for enhancement of the level of coordination between provincial and district grids. © 2011 State Grid Electric Power Research Institute Press.


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.


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.


Zheng J.,Zhejiang University | 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: 2011

Some uncertainties associated with wind power generators are expressed with probability measures, and the probabilistic load flow is calculated by the combined use of cumulants and Gram-Charlier series. Three risk-controlling strategies, including specifying the smallest acceptable probability for each branch power flow limit not violated, that for the whole system, and the security margin of branch power flows in the whole system, are introduced into the transmission system planning for enhancing the ability of the system against security/reliability risks. A security risk index is then defined by integrating the probability of system power flow limits not violated and the security margin of branch power flows in the whole system. A multi-objective transmission system planning model is next developed with the transmission investment and the security risk index as the objective functions, and in this way the security/reliability and economics associated with transmission system planning schemes could be well compromised. A cost-benefit index is employed to evaluate the performance of transmission system planning schemes. The model developed is solved by the well-established genetic algorithm, and the feasibility and effectiveness are demonstrated by 18-bus and 46-bus test systems. ©2011 State Grid Electric Power Research Institute Press.


Yang Y.,South China University of Technology | Wen F.,Zhejiang University | Li L.,Guangdong Power Dispatching Center | Wang K.,Guangdong Power Dispatching Center | Yang X.,Guangdong Power Dispatching Center
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2011

How to reasonably account for the mutually constrained relationship among transmission capacities of different areas, so as to implement optimized and coordinated utilization of the whole network capacity and hence to maintain the secure and reliable operation of a power system, is an important problem to be resolved in the decision-making procedure of available transfer capability (ATC). Given this background, a multi-objective programming based framework is presented for coordinated decision-making of transmission capacities among different areas, so as to ensure that the obtained schemes do not exceed the capability of the network supplying the given load and avoid the significant decrease of the ATC in the whole system due to the excessive employment of the transmission capacity in a given area. First, an optimal power flow based chance constrained programming model for the optimal coordinated decision-making of transmission capacity is developed, with the sum of the power in the interconnection lines among different areas as the objective function and the system security limits as constraints, and hence in the maximum transmission capacity such obtained an adequate amount of capacity margin has been retained. Next, a stochastic load flow embedded multi-objective differential evolution algorithm is employed for solving the developed optimization model. Finally, the IEEE 118-bus system is served for demonstrating the essential features of the developed model and method. © 2011 State Grid Electric Power Research Institute Press.


Zheng J.,Zhejiang University | Wen F.,Zhejiang University | Li L.,Guangdong Power Dispatching Center | Wang K.,Guangdong Power Dispatching Center | Gao C.,Guangdong Power Dispatching Center
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2013

The principle of optimal EPP (Efficiency Power Plant) placement is proposed and with the consideration of the optimal EPP placement, a two-level planning model based on two-level planning theory is developed for transmission system, of which, the upper model takes the minimum total cost of transmission system and EPP investment as its objective while the lower model takes the minimum cost of EPP investment as its objective. With the interaction between two levels, the transmission system planning scheme is finally determined by the upper model. A hybrid algorithm combining genetic algorithm and primal-dual interior method is adopted to solve the proposed planning model. Results of case study for 18-bus and 46-bus systems verify the feasibility and efficiency of the proposed model and algorithm.


Zheng J.,Zhejiang University | 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: 2013

An energy storage system (ESS) can provide ancillary services such as frequency regulation and reserves, as well as smooth the fluctuations of wind power outputs, and hence improve the security and economics of the power system concerned. The combined operation of a wind farm and an ESS has become a widely accepted operating mode. Hence, it appears necessary to consider this operating mode in transmission system expansion planning, and this is an issue to be systematically addressed in this work. Firstly, the relationship between the cost of the NaS based ESS and its discharging cycle life is analyzed. A strategy for the combined operation of a wind farm and an ESS is next presented, so as to have a good compromise between the operating cost of the ESS and the smoothing effect of the fluctuation of wind power outputs. Then, a transmission system expansion planning model is developed with the sum of the transmission investment costs, the investment and operating costs of ESSs and the punishment cost of lost wind energy as the objective function to be minimized. An improved particle swarm optimization algorithm is employed to solve the developed planning model. Finally, the essential features of the developed model and adopted algorithm are demonstrated by 18-bus and 46-bus test systems. © 2013 State Grid Electric Power Research Institute Press.


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.

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