Power system stabilyzer PSS - PWX POWER

Power System Stabilizer PSS – PWX POWER

The PWX Power is the Power System Stabilizer that acts jointly to the Excitation and Voltage Regulation System. The system´s main function is to damp electromechanical oscillations between generators.
When using Power Stabilizer Systems (PSS), the first reference to the basic concept that we know was presented in an article by Gaden, “Etudes de Stabilité”, in 1947. The Frenchman said that in order to achieve a good damping of oscillation in the interconnected systems, instead of turning to the speed governors, the most efficient thing to do was to act through the automatic voltage regulators in a way to make the voltage in the system charges to vary in phase jointly with the frequency drift. This concept is based in the fact that voltage variations generate transitory power variations, and, being those in phase with the frequency drifts, it would generate damping torques.
The Power Stabilizer Systems PWX Power provides to the Electric System where it is installed:

  • Damping of oscillation modes: Local Mode, Intra plant Mode, Inter area Mode;
  • A more equilibrated distribution of the efforts with an adequate voltage profile;
  • Damping of the low frequency common mode of speed regulation;
  • Flexibility to adjust the gain in the slow common mode, independently of the adjustment for the inter area and local modes.

The PWX has a structure of control based in the Accelerating Power synthesized from speed and electric Power mensurations, according to the recommendation of Eletrobrás and the model adopted by IEEE (Standard 421.2 – 1990), supplying a stabilizer system additional to the voltage regulator control mesh, of which the time constants are much smaller than the time constants of the speed governor.