The Research Of Power System Low Frequency Oscillation On Resonance Mechanism

Low frequency oscillation is an important problem which always affects the security and stabilization of power system. This dissertation concentrates on the research of power system low frequency oscillations of resonance mechanism. The effects of system's influential factors on oscillations, resonance oscillations in multi-machine power systems and the reasons of resonance oscillations are comprehensively studied in this paper. The main contributions of this dissertation are listed as following: 1. In accordance with the resonance mechanism of low frequency oscillations, the characters of oscillations and the effects of system's influential factors on oscillations are analyzed in this paper. 2. Low frequency oscillation resonance mechanism of two-machine system was established in this paper. The relations between natural oscillation frequency and damping of two-machine system were analyzed. Four-machine two-area system and southern network of Hebei province were taken as the research object. Low frequency oscillation of resonance mechanism in multi-machine power systems is analyzed using PSS/E. 3. The effects of variations of steam turbine's original and final parameters on output machine power were discussed. The interactions between turbine's thermal system and power system are considered. Then the reason of low frequency oscillation of resonance mechanism is found from thermal system of steam turbine. 4. The pressure-power model of turbine is established. The relation between the variations of turbo-pressure and power system resonance oscillation has been discussed. A conclusion from the simulation is drawn that the variations of turbo-pressure might cause power system low frequency oscillation of resonance mechanism.