Stability Assessment of a System Comprising a Single Machine and Inverter with Scalable Ratings

Brian Johnson, Yashen Lin, Vahan Gevorgian, Victor Purba, Sairaj Dhople

Research output: Contribution to conferencePaperpeer-review

27 Scopus Citations


Synchronous machines have traditionally acted as the foundation of large-scale electrical infrastructures and their physical properties have formed the cornerstone of system operations. However, with the increased integration of distributed renewable resources and energy-storage technologies, there is a need to systematically acknowledge the dynamics of power-electronics inverters - the primary energy-conversion interface in such systems - in all aspects of modeling, analysis, and control of the bulk power network. In this paper, we assess the properties of coupled machine-inverter systems by studying an elementary system comprised of a synchronous generator, three-phase inverter, and a load. The inverter model is formulated such that its power rating can be scaled continuously across power levels while preserving its closed-loop response. Accordingly, the properties of the machine-inverter system can be assessed for varying ratios of machine-to-inverter power ratings. After linearizing the model and assessing its eigenvalues, we show that system stability is highly dependent on the inverter current controller and machine exciter, thus uncovering a key concern with mixed machine-inverter systems and motivating the need for next-generation grid-stabilizing inverter controls.

Original languageAmerican English
Number of pages6
StatePublished - 13 Nov 2017
Event2017 North American Power Symposium, NAPS 2017 - Morgantown, United States
Duration: 17 Sep 201719 Sep 2017


Conference2017 North American Power Symposium, NAPS 2017
Country/TerritoryUnited States

Bibliographical note

See NREL/CP-5D00-67974 for preprint

NREL Publication Number

  • NREL/CP-5D00-70963


  • analytical models
  • inverters
  • phase locked loops
  • power system dynamics
  • power system stability
  • stability analysis
  • voltage control


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