Application of power system energy structures to track dominated oscillation paths and generator damping contribution during low-frequency oscillations

The high penetration of renewable energy into power systems and expansion of interconnected power grid frequently and uncontrollably result in low-frequency oscillation. Low-frequency oscillation is potentially dangerous for power systems. However, acquiring dominated oscillation paths and generator damping properties are quite helpful for system operators when taking appropriate measures to suppress these oscillations. In this study, a method for the online tracking of dominated oscillation paths and generator damping contribution during low-frequency oscillations is proposed on the basis of the damping loss factor (DLF) and two improved forms of power system energy structure (PSES). DLF in elasticity mechanics is introduced to quantitatively establish the relationship between dissipation energy and damping ratio for each mode. On the basis of the PSES framework, the dissipation energy composition during low-frequency oscillation is analyzed. Then, based on the dominance of the aperiodic component in the dissipation energy, two improved forms of PSES are derived with different distributions of dissipation energy. Subsequently, based on the DLF and improved forms of PSES, two dissipation energy-based indexes are proposed to realize the online tracking of dominated oscillation paths and evaluate the generator damping contribution (including renewable energy generators) during low-frequency oscillations. Finally, the accuracy of the proposed method is verified by simulating the “16-machine, 5-area” system as a practical power system in China.