A Decentralized Output Feedback Controller to Improve Power System Damping with Virtual Synchronous Machines

Virtual synchronous machine (VSM) is a promising control strategy for inverter-based resources (IBRs) as it can provide desired inertia and frequency support in an inverter-dominated grid. However, it can potentially introduce frequency and power oscillations among multiple IBRs in a similar way as synchronous machines oscillate against each other. To overcome this challenge, a decentralized output feedback controller is proposed in this paper. The controller consists of two loops: output power feedback and frequency feedback. The controller parameters are tuned through an efficient gradient based method. A washout filter is also added to ensure that the steady state power sharing is not affected by the controller. Small signal and simulation case studies are conducted in test systems with different levels of inverter penetration. Results show that dynamic performance of the system can be improved by applying the proposed controller.