The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
K.c. Liu - One of the best experts on this subject based on the ideXlab platform.
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A load flow and fuzzy linear programming based External Network modeling approach
IEEE Transactions on Power Systems, 1994Co-Authors: C.n. Lu, K.c. Liu, Rong-ceng Leou, M. UnumAbstract:A new External Network modeling approach is proposed in this paper. This approach is based on load flow solutions and a fuzzy linear programming formulation. The idea of the proposed method is to find an acceptable solution that matches most closely to the knowledge there is for the External Network. Uncertainties of the External Network data are modeled by using fuzzy set theory. Test results have shown that the proposed method provides a stable and flexible tool for finding an estimated real-time Network solution. Contingency analysis performed on the obtained models has indicated that the External Network solutions are acceptable.
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An External Network modeling for on-line security analysis
Conference Papers Power Industry Computer Application Conference, 1Co-Authors: K.c. Liu, S. VemuriAbstract:A state-estimation-based External power Network modeling approach is proposed. The proposed approach is designed to improve the numerical stability and provide an External Network model for online security analysis. An initial load flow study that provides a preliminary solution for the External Network is followed by a state estimation using pseudo-measurements and proper weighting factors. Methods for handling multiple observable islands in the External Network modeling process are described, and simulation tests are carried out on a practical system with realistic complexity. The proposed method provides a way of dispersing External data errors to the remote portions of the External Network. Information for error detection and identification is available from the proposed method. It is believed that continual update of the External Network model using real-time data available from neighboring utilities in conjunction with the identification and removal of erroneous data assumptions could lead to a more accurate and realistic External Network for use during online contingency analysis. >
Chen Xu-guo - One of the best experts on this subject based on the ideXlab platform.
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Development and Application of Real-Time External Network Equivalent System for Sub-Transmission Networks
Power system technology, 2005Co-Authors: Chen Xu-guoAbstract:An External Network equivalent model must follow the change of operation modes of the External Network in order to ensure computing precision of EMS application software in area Network control center.To improve the practicability of EMS software in area Network control center,a new system,which can automatically create an online External Network equivalent model for EMS/DTS usage of area Networks,is realized.According to IEC61970 CIM standard,the system gets the whole Network model and its real-time data from the existing EMS of provincial control center,then the system automatically creates an External Network equivalent model and sent to area control centers by WAN according to IEC61970 CIS/CORBA standard for further use of area Network control center EMS/DTS.External Network model can be flexibly made in the equivalent system.Partial buffer system in the External Network can be set up automatically or selected manually to balance the equivalent calculation precision and speed.This system runs automatically in online mode,and provides External Network equivalent model and corresponding real-time data all the time for area Network.This system has been put into practical operation and the operation results show that the correctness of EMS/DTS calculations in area control center is greatly improved by this equivalent system.
George N. Korres - One of the best experts on this subject based on the ideXlab platform.
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A partitioned state estimator for External Network modeling
IEEE Transactions on Power Systems, 2002Co-Authors: George N. KorresAbstract:This paper presents a partitioned state estimation (SE) method for real-time External Network modeling. The method utilizes an unreduced model of the External Network and it is based on the SE approach. Since the External Network model must not contaminate the internal system state and power mismatches at boundary buses should be minimal, the boundary measurements (tie-line flows and boundary injections) should be critical. Any type of real-time measurements (power flows and injections) can be used. The entire system state is computed by a two-pass method based on measurement model partitioning. The method is based on the fast decoupled model and it can be easily implemented by modifying an existing SE program. Partitioned observability and bad data processing schemes have been developed for the internal and External Networks. The External system model can be dynamically updated when changes on topological or analog measurements happen. The method is tested on the IEEE 14-bus system and a 2040-bus system. Contingency analysis is performed and the results are compared with those of load flow (LF) studies which consider the same contingencies.
Yannick Phulpin - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of Network Equivalents for Voltage Optimization in Multi-Area Power Systems
IEEE Transactions on Power Systems, 2009Co-Authors: Yannick Phulpin, M. Begovic, Marc Petit, Jean-baptiste Heyberger, Damien ErnstAbstract:The paper addresses the problem of decentralized optimization for a power system partitioned into several areas controlled by different transmission system operators (TSOs). The optimization variables are the settings for taps, generators' voltages and compensators', and the objective function is either based on the minimization of reactive power support, the minimization of active power losses, or a combination of both criteria. We suppose that each TSO assumes an External Network equivalent for its neighboring areas and optimizes without concern for the neighboring systems' objectives its own optimization function.We study, in the context where every TSO adopts the same type of objective function, the performance of an iterative scheme, where every TSO refreshes at each iteration the parameters of its External Network equivalents depending on its past internal observations, solves its local optimization problem, and then, applies its “optimal actions” to the power system. In the context of voltage optimization, we find out that this decentralized control scheme can converge to nearly optimal global performance for relatively simple equivalents and simple procedures for fitting their parameters.
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External Network Modeling for MVAr Scheduling in Multi Area Power Systems
2007Co-Authors: Yannick Phulpin, M. Begovic, Marc PetitAbstract:Multi area power systems work most often with a poor inter-regional coordination about reactive power concerns. Transmission system operators typically do not possess a detailed knowledge about voltage profile across interconnected power systems. In this context, reactive power scheduling may be inefficient and inter-regional reactive power flows become a decisive issue. This inefficiency, associated with economic constraints and increasing stress on interconnection lines, may lead to conflicts, which could be partially avoided with a better scheduling strategy. In addition to inter-utility agreements, part of the solution could be to use appropriate External Network modeling. Different modeling are thus presented in this paper and illustrated with an IEEE 118 bus system with 2 separately controlled regions, whose scheduling objective is to minimize active power losses. The regional scheduling process is described and the state of the interconnected power system is compared with a global optimization. Finally, the influence of the External Network modeling parameters and the accuracy of their forecast is commented.
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External Network Modeling forMVAr Scheduling inMulti AreaPowerSystems
2007Co-Authors: Yannick Phulpin, M. BegovicAbstract:Multiareapowersystems workmostoften witha poorinter-regional coordination aboutreactive powerconcerns. Transmission system operators typically donotpossess adetailed knowledge aboutvoltage profile acrossinterconnected power systems. Inthiscontext, reactive powerscheduling may be inefficient andinter-regional reactive powerflowsbecomea decisive issue. Thisinefficiency, associated witheconomic constraints andincreasing stress oninterconnection lines, may leadtoconflicts, whichcouldbepartially avoided withabetter scheduling strategy. Inaddition tointer-utility agreements, part ofthesolution couldbetouseappropriate External Network modeling. Different modeling arethuspresented inthis paperand illustrated withan IEEE 118bussystemwith2 separately controlled regions, whosescheduling objective istominimize active powerlosses. Theregional scheduling process isdescribed andthestate oftheinterconnected powersystemiscompared withaglobal optimization. Finally, theinfluence oftheExternal Network modeling parameters andtheaccuracy oftheir forecast iscommented.
Chen Fang - One of the best experts on this subject based on the ideXlab platform.
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Operational Reliability Assessment of an Interconnected Power System Based on an Online Updating External Network Equivalent Model with Boundary PMU
Electronics, 2019Co-Authors: Dabo Zhang, Shuai Lian, Weiqing Tao, Jinsong Liu, Chen FangAbstract:Information between interconnected power systems is difficult to share in real time, due to trade secrets and technical limitations. The regional power grid cannot timely detect the impact of changes in the operation mode of the External power grid on the regional reliability, due to faults, load fluctuations, power generation plan adjustments, and other reasons. How to evaluate the reliability of a regional power system under the conditions of information isolation is a difficult problem for the security of interconnected power systems. Aiming at this problem, an operational reliability evaluation method for an interconnected power system is proposed herein, which does not depend on External Network information directly, but only uses boundary phasor measurement unit (PMU) measurement data and internal Network information. A static equivalent model with sensitivity consistency was used to simplify the External Network to ensure the accuracy of the reliability calculation of interconnected power systems. The boundary PMU measurement data were used to update the External Network equivalent model online. The algorithm flow of the operation reliability assessment for the interconnected power grid is given. The results of an example based on the IEEE-RTS-96 test system show that the proposed method can track the equivalent parameters of the External Network without depending on the actual topological information, and calculate the reliability index of the internal Network accurately.
