Decoupled Active and Reactive Power Controllers for Damping Low-Frequency Oscillations using Virtual Synchronous Machines

In this paper, a power oscillation damping (POD) controller embedded in virtual synchronous machines (VSMs) is proposed. This controller suggests the decoupled use of both active and reactive powers to damp low-frequency oscillations present in a power network. This allows for selecting either power component or both of them to damp the oscillations. This issue is relevant since transmission system operators are imposing new connection requirements to converter interfaced generators (CIGs) requesting grid-forming capability and POD. In the literature, it has been shown that these services can be provided using the VSM control technique. However, POD controllers are more complex in VSMs than in typical grid-following converters due to the inherent coupling between active and reactive powers. The performance of the proposed POD controller is evaluated by using electromagnetic transient simulations on a benchmark two-area power system with an additional CIG unit.