A Comparative Analysis of Prominent Virtual Synchronous Generator Strategies Under Different Network Conditions

Abstract

The virtual synchronous generator (VSG) is the most widely used grid-forming inverter (GFMI) control technique. The VSG can provide enhanced ancillary services and improved dynamic response compared to conventional synchronous generators and grid-following inverters (GFLIs). Developing an improved understanding of VSG strategies is vital to deploy them in the appropriate context in power grids. Therefore, this paper provides a rigorous comparative performance analysis of prominent VSG strategies (e.g., ISE-Lab, synchronverter, Kawasaki Heavy Industries (KHI) model, and power synchronisation control (PSC)) under different network conditions (e.g., X/R ratios, network faults, and load types). Dynamic simulation studies have been carried out using a simplified test system to assess the performance of VSG models. Furthermore, comprehensive mathematical models of VSGs have been derived in order to verify the simulation results through a frequency domain stability analysis. Moreover, the offline simulation platform results have been validated in real-time using the IEEE-39 bus network on the OPAL-RT platform. According to the analysis, the synchronverter-based VSGs perform much better under low X/R ratios, fault conditions, and dynamic loads. Hence, they are more suitable for distribution grids and load centres with a high share of dynamic loads.

Keywords

• Dynamic loads
• frequency stability
• grid forming inverter (GFMI)
• system strength
• virtual synchronous generator (VSG)
• virtual inertia