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Öğe An efficient method to compute singularity induced bifurcations of decoupled parameter-dependent differential-algebraic power system model(ELSEVIER SCIENCE INC, 2005) Ayasun, S; Nwankpa, CO; Kwatny, HGIn this paper, we present an efficient method to compute singular points and singularity induced bifurcation points of differential-algebraic equations (DAEs) for a multimachine power system model. The algebraic part of the DAEs brings singularity issues into dynamic stability assessment of power systems. Roughly speaking, the singular points are points that satisfy the algebraic equations, but at which the vector field is not defined. In terms of power system dynamics, around singular points, the generator angles (the natural states variables) are not defined as a graph of the load bus variables (the algebraic variables). Thus, the causal requirement of the DAE model breaks down and it cannot predict system behavior. Singular points constitute important organizing elements of power system DAE models. This paper proposes an iterative method to compute singular points at any given parameter value. Generator angles are parameterized through a scalar parameter in the constraint manifold and identification of singular points is formulated as a bifurcation problem of the algebraic part of the DAEs. Singular points are determined using a second order Newton-Raphson method. Moreover, the decoupled structure of the DAE model is exploited to find new set of parameters and parameter increase pattern which will result in a set of equilibria including singularity induced bifurcations. The simulation results are presented for a 5-bus power system and singular and singularity induced bifurcation points are depicted together with equilibria to visualize static and dynamic stability limits. (c) 2004 Elsevier Inc. All rights reserved.Öğe Computation of singular and singularity induced bifurcation points of differential-algebraic power system model(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2004) Ayasun, S; Nwankpa, CO; Kwatny, HGIn this paper, we present an efficient algorithm to compute singular points and singularity-induced bifurcation points of differential-algebraic equations for a multimachine power-system model. Power systems are often modeled as a set of differential-algebraic equations (DAE) whose algebraic part brings singularity issues into dynamic stability assessment of power systems. Roughly speaking, the singular points are points that satisfy the algebraic equations, but at which the vector field is not defined. In terms of power-system dynamics, around singular points, the generator angles (the natural states variables) are not defined as a graph of the load bus variables (the algebraic variables). Thus, the causal requirement of the DAE model breaks down and it cannot predict system behavior. Singular points constitute important organizing elements of power-system DAE models. This paper proposes an iterative method to compute singular points at any given parameter value. With a lemma presented in this paper, we are also able to locate singularity induced bifurcation points upon identifying the singular points. The proposed method is implemented into voltage stability toolbox and simulations results are presented for a 5-bus and IEEE 118-bus systems.Öğe Electric Machinery Diagnostic/testing system and Power Hardware-in-the-Loop studies(IEEE, 2003) Ayasun, S; Vallieu, S; Fischl, R; Chmielewski, TThis paper presents an Electric Machinery Diagnostics (EMDS) system that improves on the traditional methods of either using simulation of a power system and its component or scaled down physical models to diagnose faults in Hardware Under Test (HUT). The EMDS couples actual power hardware to a virtual simulation of the power system through a Sim-Stim Interface (SSI) which sources and sinks power to the HUT, performing Power Hardware-in-the-Loop (PHIL), as shown in Fig. 1. Since the goal of the EMDS is to perform fault diagnosis when the HUT is connected to a physical system, then SSI must be transparent in terms of losses, bandwidth and dynamic range. By its very nature, the SSI adds complexity to the system by the introduction of its internal components (such as sensors, AID and D/A converters, power amplifiers and operational software). This paper gives the key issues that enables the EMDS to perform PHIL diagnostic studies enabling one to test power equipment as if the device is connected to the actual power system without risking damage to both the equipment and the actual system.Öğe Induction motor tests using MATLAB/Simplink and their integration into undergraduate electric machinery courses(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2005) Ayasun, S; Nwankpa, COThis paper describes MATLAB/Simulink implementation of three induction motor tests, namely dc, no-load, and blocked-rotor tests performed to identify equivalent circuit parameters. These simulation models are developed to support and enhance electric machinery education at the undergraduate level. The proposed tests have been successfully integrated into electric machinery courses at Drexel University, Philadelphia, PA, and Nigde University, Nigde, Turkey.
