Multi-layered defense against oscillations

Abstract

Increasing shares of inverter-based resources (IBRs) in power grids are triggering complex dynamic interactions and new stability challenges. A particular challenge for system operators is poorly damped sub-synchronous oscillations (SSO) induced by adverse interaction among IBRs through the network. These oscillations are difficult to foresee, threaten system security and often force grid operators to limit the instantaneous share of IBRs. The Control and Power research group at Imperial College London are working with the Network Operability team in National Energy System Operator (NESO) in the UK to develop a multi-layered defense strategy to identify and mitigate the risk of poorly damped SSO. Starting from advanced IBR control design which is the genesis of the SSO problem, these layers are: 1) an enhanced IBR connection compliance process capture the risk of SSO more comprehensively, 2) new system strength metrices to identify parts of the grid vulnerable to SSO, 3) characterize operating point dependency of IBRs to detect incipient SSO near real-time and 4) post-event root-cause analysis for targeted and effective mitigation of SSO. Success of this research will enable secure grid operation with high fractions of renewables to facilitate net zero transition