Nonlinear Modal Decoupling: a new approach to real-time power system stability analysis and control (Slides)

With the increasing penetration of IBRs, a power system can exhibit more complex dynamics such as nonlinear oscillations, near-resonances and unanticipated instabilities. Conventional small-signal and transient stability analyses for power systems will no longer be adequate. For real-time stability analysis and control of a future power system modeled by a network of many nonlinear oscillators, this talk introduces a new methodology named “Nonlinear Modal Decoupling” that inversely constructs as many decoupled nonlinear oscillators as the system’s oscillation modes of interests. Such decoupled oscillators together provide a fairly accurate representation of the system’s stability and oscillatory behaviors under both small and large disturbances. Each decoupled oscillator, although nonlinear, has one degree of freedom and can easily be analyzed and controlled using a direct method to ensure the stability of the original system regarding its corresponding mode. When any oscillator foresees a transition from sustained oscillation to instability in real time from wide-area measurements, a newly proposed IBR-based distributed controller can quickly stabilize the power system.