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Voltage sag is among the major power quality disturbances that can cause substantial loss of product and also can attribute to malfunctions, instabilities and shorter lifetime of the load. Accurate voltage sag source location can help to minimize the loss and problems caused by voltage sag in a power distribution system. This paper presents a development of a current component index (CCI) algorithm to locate the source of voltage sag in a power distribution system. The product of the RMS current and the power factor angle at the monitoring point is employed for the sag source location. A graph of this product against time is plotted. The voltage sag source location is determined by examining the magnitude of the current component index at the beginning of the sag. If the magnitude of the CCI during sag is higher than the magnitude of CCI before sag, it indicates that the voltage sag source is in front of the monitoring point. On the other hand if the magnitude of the CCI during sag is lower than the magnitude of CCI before sag, it indicates that the voltage sag source is in behind the monitoring point. The proposed method has been verified by simulations on a radial distribution system. Comparative studies with other method namely, the slope of the line fitting parameters of current and voltage method were also conducted in order to highlight the strength of the proposed method [ABSTRACT FROM AUTHOR]

Most of electrical power utilities in the world are required to ensure that electrical energy requirement from the customer is served smoothly in accordance to the respective policy of the country. Despite serving the power demands of the country, the power utility has also to ensure that the electrical power is generated within minimal cost. Thus, the total demand must be appropriately shared among the generating units with an objective to minimize the total generation cost for the system in order to satisfy the economic operation of the system. Economic dispatch is a procedure to determine the electrical power to be generated by the committed generating units in a power system so that the total generation cost of the system is minimized, while satisfying the load demand simultaneously. This paper presents the economic power dispatch problems solved using Ant Colony Optimization (ACO) technique. ACO is a meta-heuristic approach for solving hard combinatorial optimization problems. In this study, the proposed technique was tested using the standard IEEE 26-Bus RTS and the results revealed that the proposed technique has the merit in achieving optimal solution for addressing the problems. Comparative studies with other optimization technique namely the artificial immune system (AIS) were also conducted in order to highlight the strength of the proposed technique. [ABSTRACT FROM AUTHOR]

The article discusses the concept of universal adaptive control by considering a simple class of scalar systems and also motivates the use of switching functions for this class. An alternative to the Nussbaum functions, that arise naturally in the feedback law if the sign of the high-frequency gain of the system to be stabilized is unknown, are considered. Switching functions and unbounded switching functions are discusses. The paper then gives a brief overview of how the switching functions described in the study are related and used to solve the universal adaptive control problem for different classes of systems.