DESIGN OF POWER SYSTEM STABILIZERS BASED ON THE MODEL OF SINGLE MACHINE INFINITE BUS POWER SYSTEM

Abstract

Problem of damping electromechanical oscillations in electric power systems
is not new. Since the 1950s, when power systems started to get bigger and ever
more stressed, engineers have been looking for synchronous generator controllers
that could improve damping of oscillations. The most popular tool for power
system stability enhancement is the power system stabilizer (PSS) which provides
an auxiliary control loop to the main automatic voltage regulator (AVR). PSS
structure usually follows one of IEEE standards [1]. PSSs are usually of the single-
input type with constant parameters (time-invariant) but two-input stabilizers
are used too. PSS design is usually based on the compensation of plant
frequencycharacteristics, optimization of defined quality indices, or shifting poles
of the considered system to appropriate locations.The problem of the poorly
damped low-frequency (0.1 - 2Hz) oscillations of power systems has been a
matter of concern to power engineers, because they limit the power transfer
capability in power systems. The power systems stability is also affected by these
poorly damped oscillations and can lead to the system instability. The paper
presents a design PSSs to enhance power systems stability and improve power
transfer capability. MATLAB dynamic model was developed for a power system
and lead-lag PSS structure is considered in the model. Damping torque technique
is applied to tune the PSS parameters. The results of this technique have been
verified by eigenvalue analysis and time-domain simulations. The simulations
results show that the system time responses under different operating conditions
are well damped with the designed PSS.