Estimation of Equivalent SCR for Offshore Wind
For power system engineers designing offshore wind farms, this provides a more accurate ESCR estimation method that accounts for converter dynamics, improving stability analysis in weak grids.
This paper introduces a novel hybrid EMT-TPN method to estimate the equivalent short-circuit ratio (ESCR) at the offshore point of connection for offshore wind power plants, addressing limitations of traditional SCR metrics by incorporating converter dynamics. The method accurately captures ESCR variations with cable lengths, shunt reactors, and grid strength, and demonstrates correlation with voltage stability, highlighting STATCOM support in weak grids.
The integration of offshore wind power plants (OW-PPs) into weak grids can pose stability challenges due to the interaction between inverter-based resources (IBRs), Flexible AC Transmission Systems (FACTS) and the grid. In this context, long HVAC transmission systems, relatively common for OWPPs, can exacerbate the stability challenges. Therefore, this paper introduces a novel methodology for estimating the equivalent short-circuit ratio (ESCR) at the offshore point of connection (PoC), combining analytical two-port network (TPN) modeling with electromagnetic transient (EMT) simulations. The approach derives the Thevenin equivalent impedance for passive and active components, enabling accurate ESCR computations without complex derivations. Limitations of traditional SCR metrics are addressed by incorporating the dynamics of the converters, such as static synchronous compensators (STATCOMs), into a hybrid EMT-TPN method for synthesizing equivalent impedances. The process is then verified on the CIGRE OWPP benchmark and is found to capture ESCR variations with cable lengths, shunt reactors, and grid strength. Additionally, the results emphasize the correlation between the ESCR and voltage stability, highlighting the role of STATCOMs in supporting voltage stability in weak grids. This modular framework aids in OWPP design and stability analysis for converter-dominated systems.