The Study On Application Of PSS In Damping The Low Frequency Oscillations In Power System

With the development of economic, power system makes great progress. Electromechanical oscillations have gained an increasing concern. The aim of this paper is to damping low frequency to guarantee the power systems running safely and stability.The traditional power system stabilizer(PSS), which has the good effect of damping low-frequency oscillation, so it is used widely in the power system.The transfer function block diagram of single machine infinite bus system is introduced in this paper, including deriving the all parameters of the mode, analyzing mechanism of low-frequency oscillation. Verify fast, high magnification excitation system for power system low frequency oscillation effects. Then the PSS damping controller model is introduced, the specific forms of additional torque provided by excitation system and the PSS damping low-frequency oscillation principles is analyzed, and the phase compensation method is also used to set the parameter of PSS damping controller. Then PSS simulation can verify play an effective role of damping low frequency oscillation system.The state equation of single machine infinite bus system and multi-machine system with PSS is established respectively, we also derived the specific expression of all parameters in multi-machine system mode, which provided the theoretical basis for eigenvalue analysis and analysis of various control strategies in the power system with PSS damping controller.Finally, this paper presents an approach to implement the parameters optimization of PSS controller. With genetic algorithm (GA), this approach can ensure a good damping effect over all the main frequency band of low frequency oscillations. Furthermore, the optimization object can be flexibly modified through a weighted calculation to different frequency bands. The simulation results illustrate that this approach is valid and can be used for reference.With characteristic root analysis, determines the position of PSS installation and analyzes the system damping effect under different parameters.Based on MATLAB establish a four machine two regional system with the traditional PSS parameters and genetic algorithm of simulation analysis, the genetic algorithm to optimize the low frequency oscillation PSS parameters of the system can better damper.