George J. Cokkinides

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(PSERC) is a multi-university Center conducting research on challenges facing the electric power industry and educating the next generation of power engineers. More information about PSERC can be found at the Center's website: Notice Concerning Copyright Material PSERC members are given permission to copy without fee all or part of this publication for(More)
This paper addresses numerical oscillations encountered in power system dynamic simulation resulting from trapezoidal numerical integration rule. Two methods are presented to eliminate the numerical oscillations: trapezoidal with numerical stabilizer method and Gear’s second order method. A detailed comparison is given regarding the accuracy of the(More)
Abstract A new tool for computing and visualizing the operation of power system components and systems is presented. One component of the tool is a time domain simulator that operates in the background within a multitasking environment. Visualization and animation objects can retrieve data in real time from the time domain simulator and display a detailed(More)
This paper presents the application of the virtual test bed for visualization and animation of protective relaying problems. The development of protective relaying animation and visualization objects as well as the interfacing with the virtual test bed is described. Two examples of protective relaying animation are presented: (a) modified mho relays and (b)(More)
The most common load type consists of induction motors. The operational characteristics of these motors play an important role in the power system operation and control. More accurate models of induction machines will result in more realistic power system simulation. This is particularly important in today’s environment where power systems are operated(More)
Present state estimator performance is not 100% reliable. Specifically, there is significant probability that the state estimators may not converge to an acceptable solution. On an industry wide basis, the probability of non convergence is about 5%. The reasons for this performance have been investigated and have been reported in earlier papers. In this(More)
In a deregulated environment, independent generators and utility generators may or may not participate in the load-frequency control of the system. For the purpose of evaluating the performance of such a system, a flexible method has been developed and implemented. The method assumes that load frequency control is performed by an ISO based on parameters(More)
This paper presents the architecture as well as example applications of the Virtual Test Bed (VTB). The VTB is a simulation environment being developed as a virtual prototyping tool for modern electric power distribution systems, with emphasis on power electronics. The VTB is built around an efficient and flexible network solver, an advanced visualization(More)
The SuperCalibrator concept was introduced to take advantage of the characteristics of GPSsynchronized equipment (PMUs). Specifically, GPS-synchronized equipment has the capacity to provide precise phase measurements (to 0.01 degrees accuracy) and relatively good quality magnitude measurements (up to 0.1% accuracy). However in a practical environment this(More)