A New Robust Hopf Oscillator: Towards Resilient Operation of Microgrids in Grid Connected and Islanded Modes

Virtual oscillator-based techniques have been used with grid-connected inverter to address many existing challenges. The existing Hopf oscillator (HO) based inverter system can be operated in both grid-connected and islanded modes however, it exhibits limitations, such as sensitivity to parametric uncertainties, especially in multi-inverter systems and islanded mode. This paper proposes a new modified robust HO to enhance its robustness against external disturbances and parametric uncertainties in microgrids. The proposed modified Hopf oscillator (MHO) ensures robust control against persistent disturbances. Further, to reduce the transient oscillations, such as amplitude build-up, experienced by the system during the initial state, a controller is incorporated that suppresses the disturbances through sliding-mode dynamics and provides coordinated control among the parallel-connected inverters subjected to varying grid conditions. The hybrid control (HC) ensures that the system operates efficiently and performs better dynamically. The simulated studies and the Real-Time digital simulator (OPAL-RT) based results validate the efficacy of the proposed strategy to achieve resilient control, improved stability, and robust synchronization in comparison to the existing techniques.