The electromechanical coupling model is employed to define the all-mode shape and torsional mode shape, and deduce the linear solutions of torques. Based on the solutions of torques, mode shapes of torques and mode co...
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Cascading trips caused by flow transferring are the crucial causation of a lot of well-known blackouts. It severely threatens the security and reliability of powersystems. Flow transferring relativity factor (FTRF) i...
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Cascading trips caused by flow transferring are the crucial causation of a lot of well-known blackouts. It severely threatens the security and reliability of powersystems. Flow transferring relativity factor (FTRF) is extended from single branch removal event to multi-branches removal event. According to refraction and reflection process of flow transferring, the calculation formula of FTRF for multi-branches chain removal event is deduced. Moreover, by using the relationship of node injection currents and branch currents, a method of post-fault branch current estimation and a flow transferring identification algorithm based on WAMS to distinguish flow transferring in transient period is presented. The simulation results of 10-generator 39-bus New England system show that the proposed estimation method and the identification algorithm work well.
The lack of quantitative stability analysis software for powersystem is one of the main reasons for losing good chance to implement the emergency control and even finally resulting in the large outage. Recently, the ...
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The lack of quantitative stability analysis software for powersystem is one of the main reasons for losing good chance to implement the emergency control and even finally resulting in the large outage. Recently, the rapidly developing wide area measurement system (WAMS) gives a new way for quick on-line quantitative transient stability assessment. Starting with the single machine energy function, the relationship between the variation rate of transient unbalance energy and multi-swing stability was analyzed in detail, and the corresponding characteristic of the variation rate of transient energy was proved. Then, a new multi-swing stability assessment criterion based on WAMS was proposed. Numerical simulations were conducted on 6-machine 22-bus system of China electric power research institute to demonstrate the effectiveness of this criterion.
The interactions between AC and DC systems in the steady-state condition of powersystems are investigated. Through a sensitivity analysis, the influence of DC control parameters on the operation of AC/DC systems and ...
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The interactions between AC and DC systems in the steady-state condition of powersystems are investigated. Through a sensitivity analysis, the influence of DC control parameters on the operation of AC/DC systems and that of AC control parameters on other AC parameters with the DC system existing are discussed. The sensitivity matrices and the influence factors between AC and DC systems are analyzed from various points of view. The sensitivity analysis made in this paper is expected to be of practical significance in such problems as load flow control, parameter regulation, voltage estimation, etc.
The paper proposed a novel decentralized approach for congestion management via Optimal Resource Allocation (ORA) for the forward markets. The availab.e capacities of possible congested transmission lines are consider...
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The paper proposed a novel decentralized approach for congestion management via Optimal Resource Allocation (ORA) for the forward markets. The availab.e capacities of possible congested transmission lines are considered as commonly shared resources for bilateral and multilateral transactions in the market. Each transaction maximizes its profit using limited capacity of transmission line allocated by the ISO. Through the proposed decentralized optimization algorithms, the ISO searches the optimal allocation of the capacities of congested transmission lines to the individual transactions and finally the same market efficiency (social welfare) as centralized optimization is achieved. This decentralized approach is more suitable for power market environment since it does not require private and sensitive information submission from individual transactions to the ISO and the resource allocation decision is always feasible during iterations. The mathematical model, calculation procedure and relevant proof are presented. The computer test results from the IEEE 30 bus system show clearly the effectiveness of the approach and its consistency with the centralized optimization.
A method, based on Genetic Algorithm, for optimizing multivariable PID controllers, is being proposed. The global parameters of the PID controller are optimized here by utilizing the generic framework of genetic algor...
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A method, based on Genetic Algorithm, for optimizing multivariable PID controllers, is being proposed. The global parameters of the PID controller are optimized here by utilizing the generic framework of genetic algorithm. The only prerequisite asked for by the method is that the object function can be numerically evaluated, without any restrictions concerning the concrete form of the controlled object's model, and without requiring any analytical relationship between the object function and the control parameters as well. The method is therefore featured by superior universality. Simulation of a steam turbine generator set' s controlsystem shows that, though the decoupling effect of multivariable PID controllers, designed by the mentioned method, is somewhat inferior to the optimization of parameterized high order normal matrix design method, but has, in respect to decoupling effect, remarkable improvements in comparison with multi-loop PLD control. It has, in addition, a certain disturbance resistant capability, and robustness;is exhibiting good dynamic behavior and proves the method's feasibility.
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