Framework of real-time grid stabilization technology for suppression of sub-synchronous oscillations

Abstract

In this paper, we propose a new framework to address the issues of sub synchronous oscillations (SSOs) in power grids with high renewable (e.g., wind and photovoltaic) penetration. Inverters are used for integrating these renewables into power grids and these sources are known as inverter-based resources (IBRs). The high penetration of IBR causes SSO phenomena due to its fast dynamics, non-linearity, and interaction with the grid. SSOs in voltage and current cause instabilities in the power grid, which may lead to blackouts in the worst case. To assess SSOs, time domain simulations are performed during planning by grid operators, but they are time consuming process therefore not applicable to real-time applications considering variable output power generation from IBRs. Therefore, real-time control of SSO management (detection and suppression) by precise control of output power is required. In the proposed framework first, models of IBR are linearized at several small output levels by its impedance modelling in frequency domain in advance or off-line. Second, stability analysis is done based on impedance of grid and impedance of IBRs. To verify the concept of the proposed framework, we simulated SSOs in IEEE testbed by modelling and aggregating a 400-MW wind farm connected to a series-compensated transmission line in PSCAD.