DefinePK

Abstract

The increasing magnitude and difficulty of interconnected power systems due to competitive energy markets, economy and population development have created the need to operate the power systems close to their capacity limits. This leads sometimes to stability problems or poor dynamic behaviours like power oscillations. These oscillations can cause a reduction of the system components lifetime, expensive operations of the electrical grids and in the worst case, risks of partial system collapses. On the other hand, in the synchronous generator, the damping that the field and damper windings provide to the rotor oscillations is weakened due to excitation control system action. The reason for this is that in the rotor circuits appear additional currents induced by the voltage regulation and those currents oppose to the currents induced by the rotor speed deviations. Therefore, an additional stabilizing signal was needed and the Power System Stabilizer (PSS) was developed with this aim. The PSS is a feedback controller, part of the control system for a synchronous generator, which provides an additional signal that is added to the input summing point at the Automatic Voltage Regulator AVR. The PSS main function is to damp generator rotor oscillations. By adding the stabilizing signal the PSS is expected to produce an electric torque component that counteracts the mechanical dynamics. The produced electric torque component should be in phase with the deviations of the generator rotor speed in order to be able to damp the oscillations. The simulation of the proposed model was carried out using specialized power system analysis toolbox (PSAT).