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Energy analysis of power system low frequency oscillation of resonance mechanism

Some power oscillations occurring in the actual power system, which are not induced by negative damping mechanism, has been explained well using this resonance mechanism of power system low frequency oscillation. The resonance mechanism in power system is explained from the energy point of view in this paper. The rotor energy functions of two-machine system and multi-machine system were deduced, and then the low frequency oscillation resonance mechanism of two-machine system was established. The energy characteristics of low frequency oscillation of resonance mechanism in two- machine system were analyzed through the simulations in Matlab. Finally, Southern Power Grid of Hebei province was taken as a multi-machine case. Its electromechanical oscillation modes were obtained using Small Signal Analysis Tool (SSAT), the relative rotor speed and generator power angle were obtained from the Power System Simulator/Engineering (PSS/E) simulation results and the energy of generator rotor was calculated using deduced energy function of multi-machine system. Its result causes the physical process of power oscillation to be clearer, and is helpful to well understand the power system low frequency oscillation of resonance mechanism.