Identifying Subsynchronous Oscillation Sources at Component Level of DFIGs Using Subsynchronous Modal Energy

The subsynchronous oscillation (SSO), which has greatly threatened the double-fed induction generator (DFIG) integrated power system, can be triggered by various components of the DFIG. Identifying the specific internal component that induces SSO inside the DFIG is crucial for accurately understanding and efficiently eliminating incidents. However, it is difficult to locate the SSO source to the internal component of DFIG due to their complex energy transfer relationship. To address this issue, this paper proposes an SSO source location method that can locate the SSO source to the specific internal component. Firstly, based on the generalized Hamiltonian theory, the subsynchronous modal energy (SSME) balance equation of each component within the DFIG is derived. Subsequently, the SSME transmission network of the DFIG is constructed to reflect the energy transfer relationships among the internal components explicitly. Then, practical calculation methods for the SSME of each internal component are developed. Finally, based on the SSME of the internal component, a DFIG component-level SSO source location criterion is proposed. The effectiveness of the proposed method is verified under different SSO scenarios considering subsynchronous control interaction (SSCI), phasor-locked loop (PLL)-related oscillation, and forced SSO. Comparisons with existing energy-based method illustrate the superiority of the proposed method.