Nonlinear Modal Decoupling Based Power System Transient Stability Analysis
For power system engineers, this work offers a new method for transient stability analysis that accounts for nonlinear modal interactions, though it is an initial application on small to medium systems.
This paper applies nonlinear modal decoupling (NMD) to realistic power system models for transient stability analysis, deriving decoupled nonlinear oscillators to assess stability. Case studies on 3-machine 9-bus and 48-machine 140-bus systems demonstrate the approach's potential.
Nonlinear modal decoupling (NMD) was recently proposed to nonlinearly transform a multi-oscillator system into a number of decoupled oscillators which together behave the same as the original system in an extended neighborhood of the equilibrium. Each oscillator has just one degree of freedom and hence can easily be analyzed to infer the stability of the original system associated with one electromechanical mode. As the first attempt of applying the NMD methodology to realistic power system models, this paper proposes an NMD-based transient stability analysis approach. For a multi-machine power system, the approach first derives decoupled nonlinear oscillators by a coordinates transformation, and then applies Lyapunov stability analysis to oscillators to assess the stability of the original system. Nonlinear modal interaction is also considered. The approach can be efficiently applied to a large-scale power grid by conducting NMD regarding only selected modes. Case studies on a 3-machine 9-bus system and an NPCC 48-machine 140-bus system show the potentials of the approach in transient stability analysis for multi-machine systems.