Tutorial: From Frequency Scan to Immittance Based Stability Theory...

Tutorial: From Frequency Scan to Immittance-Based Stability Theory: Frequency-Domain Methods for IBR and Future Power Systems Featured Presenter: Dr. Jian Sun, Professor in the Department of Electrical, Computer and Systems Engineering, Rensselaer Polytechnic Institute (RPI);  Director of the Center for Future Energy Systems (CFES) About the Tutorial: Frequency scan has been used to identify subsynchronous resonance (SSR) involving generators since 1970’s. The method is intuitive and easy to use but remained for a long time an ad hoc numerical procedure. This changed with the establishment of the small-signal sequence immittance theory of which frequency scan is a simplified application. The more general definition and mathematical development of immittance-based frequency-domain models at both the component and system level as well as stability analysis based on such models opened new applications and provided a general framework to address stability challenges in renewable generation, HVDC transmission, and future power systems. This presentation gives an overview of the immittance-based stability theory and its successful application to solve IBR-grid interconnection problems such as high-frequency resonance of HVDC converters, supersynchronous resonance of wind and PV inverters in weak grids, as well as various subsynchronous problems. New developments to address system-wide stability concerns of future grids dominated by IBR are also reviewed.