Sub-Synchronous Modal Energy-Based Method for Locating SSO Sources in Power Systems With DFIGs
Xi Chen, Xi Wu, Han Yang, Chenyu Wu, Bin Wang
Abstract
Equipment safety and system stability are increasingly threatened by sub-synchronous oscillations (SSOs) for the mounting proportion of doubly-fed induction generators (DFIGs) in power systems, which calls for accurate and timely identification of SSO sources. In this article, a sub-synchronous modal energy (SSME)-based approach is proposed for locating SSO sources in power systems with DFIGs. Firstly, the sub-synchronous modal energy balance equation of a power system with DFIGs is derived via generalized Hamiltonian theory. Then, each component of the SSME balance equation is analyzed to illustrate that the flow direction of SSME serves as a suggestive criterion for identifying SSO sources. Considering the SSME of subsystems can be easily obtained online with measurement data, a novel SSO source location method is proposed based on the SSME of subsystem. Finally, the performance of the SSME-based method is demonstrated under both forced and negative-damping SSO scenarios. Simulation results validate the effectiveness of the proposed SSO source location method as well as its improvement in accuracy compared with conventional energy-based method.