Studies On Generator Damping Evaluation And Oscillation Source Location Based On Energy Flow

In the new situation of increased interconnection of the power grid and large-scale integration of renewable energy,the probability of forced oscillations in the power system has significantly increased,posing a serious threat to the safe and stable operation of the power grid.As the power source,the generator is most likely to cause forced oscillations in the system,and locating the oscillation source generator is an important step in suppressing forced oscillations.At the same time,generator damping is the main component of system damping,and studying the damping characteristics of the generator not only enables online monitoring of generator damping,but also helps in locating the forced oscillation source.Based on the analysis of dissipating energy,this paper proposes a strategy for locating the disturbance source generator.A detailed analysis of the energy dissipation of generator components is carried out,and an evaluation method for the damping contribution of generator components is proposed to achieve online evaluation of generator damping and equipment-level oscillation source localization.The specific research content is as follows.(1)A detailed analysis is conducted on the composition and transformation characteristics of forced oscillation energy flow,and a dissipating energy flow localization method based on wide-area measurement information is constructed based on the energy function of power system.The theoretical derivation and analysis of the relationship between dissipating energy,damping torque,and damping ratio clarify the consistency between dissipating energy and system damping,which lays a theoretical foundation for tracking and localizing the oscillation source and online evaluation of component damping.(2)A two-stage localization strategy based on complex dissipating energy flow and generator frequency response function is proposed.Firstly,in response to the limitations of the dissipating energy flow method,a method for calculating complex dissipating energy flow is constructed to determine the oscillation area and locate the potential source generator based on the energy flow direction,which solves the problem of reduced localization accuracy due to impedance influence.On this basis,the frequency response function of the source generator is constructed in turn.By comparing the power spectral density of the predicted current and measured current of the source generator,the interference of negative damping sources can be effectively eliminated,and the precise localization of the forced oscillation source can be achieved.Finally,simulation tests on a4-machine 2-area system and a 16-machine 80-node system verify the feasibility and accuracy of this forced oscillation source localization strategy.(3)A damping evaluation method for the generator and its components based on dissipating energy is proposed to achieve generator damping evaluation and equipment localization for oscillation sources.An energy function for generator components based on electrical parameters is constructed,and the calculated energy dissipation value is used to estimate the generator damping coefficient,which is then used to evaluate the size of the generator damping.At the same time,the damping contribution of generator components is analyzed using the damping coefficient,and the oscillation source equipment is located based on the size of the damping contribution.Simulation verification is conducted on a two-machine system and a 16-machine 80-node system,analyzing the changes in generator damping characteristics under forced oscillations of wide frequency range and different locations,and proving the effectiveness of the evaluation method for generator component damping contribution.Furthermore,based on the results of the third chapter’s oscillation source generator localization,a fine localization of oscillation source generator control equipment is achieved.