Comparative evaluation of dynamic performance of virtual synchronous machine and synchronous machines

Increasing penetration of converter-interfaced renewable generation has led to significant operational challenges for power systems. Such challenges are mainly caused by the different capabilities and dynamic responses of the converters compared with synchronous machines, e.g. converters do not naturally provide inertia to the system and contribute limited fault level with very different fault characteristics. Virtual Synchronous Machines (VSM) and Synchronous Condensers (SCs) are both considered as promising solutions to address the challenges in operating converter-dominated power systems. This paper presents comprehensive studies for evaluating and comparing the dynamic performance of VSM, SC and Synchronous Generators (SGs), under a range of grid contingency events, which include short circuit faults, frequency disturbances, voltage depression, etc. The studies aim to offer insights on the level of support VSMs can offer to the system as compared with SCs and SGs, and their advantages, potential issues and limitations that need to be considered for a wider application in the system. From the studies, it is found that the VSM system appears to have comparable performance and support to the system from the perspective of fault ride-through (FRT), provision of inertial response and reaction to voltage steps. However, while VSM can potentially provide a fast fault current injection through the implementation of appropriate control, a key limitation is on the magnitude of fault currents, so it is unlikely to be capable of offering the same level of support compared with SCs and SGs.