Stabilization of multiple unstable modes for small-scale inverter-based power systems with impedance-based stability analysis

This paper investigates the harmonic stability of small-scale inverter-based power systems. A holistic procedure to assess the contribution of each inverter to the system stability is proposed by means of using the impedance-based stability criterion. Multiple unstable modes can be identified step-by-step coming from the interactions among inverters and passive networks. Compared to the conventional system stability analysis, the approach is easy to implement and avoids the effect of potential unstable system dynamics on the impedance ratio derived for the stability analysis. PSCAD/EMTDC simulations of a Cigre LV network Benchmark system with multiple renewable energy sources are carried out. The results confirm the validity of the proposed approach.