A Comparative Analysis of Prominent Virtual Synchronous Generator Strategies Under Different Network Conditions
Chalitha Liyanage, Inam Ullah Nutkani, Lasantha Meegahapola
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., <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X/R</i> 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 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X/R</i> ratios, fault conditions, and dynamic loads. Hence, they are more suitable for distribution grids and load centres with a high share of dynamic loads.