iosr-JEEE   Volume-10 ~ Issue-4 ~ July-August 2015

Abstract: Industrial loads are mostly inductive and hence operate at low power factor. Several methods including the installation of capacitor banks are available for improving power factor in order to reduce the kilovolt ampere (kVA) demand of the load and power loss from the power supply system. However, literatures have shown that improvement of power factor has effect on switching transients which is dangerous for industrial loads and operating personnel. In this work, we investigated the effect of improving the power factor of a power system beyond 0.8 (lagging) on switching transient levels using FUMMAN industry power network as a case study. A power factor measuring tool was modelled using the mathematical relation between power factor, reactive power and active power.

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Abstract: A comparative study of monotonic and non monotonic phase LTI systems using analytical design of PID controller, by means of gain cross over frequency and phase margin specifications, is presented in the paper. The proposed methodology ensures minimum phase margin inside desired bandwidth giving accurate performance to step response for closed loop system. Concept of phase margin needs to be redefined when uncontrolled process presents minimum phase inside bandwidth. For comparative study, bode stability criterion, nyquist stability criterion and unit step response is used.

Keywords: Improved analytical controller , linear system compensation, monotonic and non-monotonic phase LTI system.

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Abstract:This paper presents the sliding mode controller design to regulate the speed control of the direct-current(DC)
motor. In this, The sliding surfaces used to derive the different control schemes presented in this work are based on an integraldifferential equation acting on the tracking-error expression. A new approach for the design of sliding mode controllers based
on first-order-plus-dead time model of the system, is developed. This approach results in a fixed structure controller with a set of
tuning equations as a function of the characteristic parameters of the model. The controller performance is judged by simulation
on model of the DC motor

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