19-04-2011, 12:39 PM
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Introduction
Power systems stabilizers (PSS) have been widely used as supplementary controllers to provide extra damping for the synchronous generators in electrical power systems.
The Single Machine Infinite Bus (SMIB) system is chosen as it is such a simple configuration which is extremely useful in understanding concept of power system stabilizer (PSS).
The Parametric uncertainty in power systems has been handled using quantitative feedback theory (QFT).
The robustness of the feedback controller has been investigated on a single machine infinite bus model
Stability
Power system stability
The oscillatory response of a power system during the transient period following a disturbance is damped and the system settles in a finite time to a new steady state operating condition, the system is stable
Stability is considered in its three aspects
Transient Stability
Dynamic Stability
Steady State Stability
Over years, considerable efforts have been devoted to improve power system stability is various ways
These attempts can be divided into three board groups.
• Generator excitation control
• Generator input power control
• System operating condition and configuration control
Excitation controllers:
Excitation controllers have been used widely in power systems for decades
The main objective is to achieve in acceptable voltage profile at the consumer terminal and to control the reactive power flow in the network
High gain, short time constant and high ceiling voltage excitation control are among the characteristics of this control loop.
Achieving this with Automatic Voltage Regulators (AVR) is possible to a large extent in the case of single machine system under dynamic conditions