Investigation of Power System Stabilizer PSS-3B in a Large Hydro Generating Unit

Abstract

Rotor angle and voltage stability are the most important aspects in stability studies of a power system. Ignorance of any of them will lead the system towards instability and subsequently to grid collapse. In this paper, disturbances caused by the rotor angle stability, such as oscillations in power delivery, deviation in rotor speed are discussed and the effect of power system stabilizer for damping of those oscillations are investigated. To realize the scenario, a synchronous generator connected with an infinity grid is considered as the test system and is modeled in Power System Computer Aided Design software. ST5B static excitation system is deployed to provide the field flux of the synchronous generator and the PSS3B power system stabilizer provides an additional stabilizing signal to the excitation system required for the improvement of the damping performance of the machine. To observe the dynamics of the machine, a fault was introduced at the middle of the transmission line. As the operating point changes in abnormal conditions, conventional PSS is unable to provide satisfactory performance. To overcome this drawback, PSS parameters were tuned by implementing the Down-hill simplex algorithm. It helped in reducing rotor angle oscillations and improving voltage stability as well. The behavior of the machine is presented in the results section to prove the superiority of the soft computing method over the conventional one.