Impact of Aggregated PV on Subsynchronous Torsional Interaction

Research output: NRELPoster


This paper investigates induced oscillation (specifically subsynchronous torsional interactions) in power systems arising from photovoltaic (PV) power modulation. Time domain simulations of a modified IEEE first-benchmark system are presented and analyzed. In the IEEE benchmark system, a PV generator was added at the same bus where the synchronous generator is connected. The impact of different parameters of the PV inverters’ volt-volt-ampere reactive (volt-var) curve on SSTI is examined. The most severe impact found arises from the time response of the inverter’s reactive power change. A second-order time response with natural frequency matching the rotor speed deviation oscillation frequency and low-damping ratio quickly drives the system to an unstable region. Although it is highly unlikely that conditions necessary for distributed energy resource-induced oscillations would occur in the field, with knowledge of this vulnerability in mind, inverters' control parameters can be designed to avoid it.
Original languageAmerican English
StatePublished - 2020

Publication series

NamePresented at the 47th IEEE Photovoltaic Specialist Conference (PVSC), 15 June - 21 August 2020

NREL Publication Number

  • NREL/PO-5D00-76904


  • DER
  • photovoltaics
  • PV
  • specifically subsynchronous torsional interactions
  • SSTI
  • volt-var


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