Reduced-Order Structure-Preserving Model for Parallel-Connected Three-Phase Grid-Tied Inverters: Preprint

Brian Johnson, Victor Purba, Saber Jafarpour, Francesco Bullo, Sairaj Dhople

Research output: Contribution to conferencePaper


Given that next-generation infrastructures will contain large numbers of grid-connected inverters and these interfaces will be satisfying a growing fraction of system load, it is imperative to analyze the impacts of power electronics on such systems. However, since each inverter model has a relatively large number of dynamic states, it would be impractical to execute complex system models where the full dynamics of each inverter are retained. To address this challenge, we derive a reduced-order structure-preserving model for parallel-connected grid-tied three-phase inverters. Here, each inverter in the system is assumed to have a full-bridge topology, LCL filter at the point of common coupling, and the control architecture for each inverter includes a current controller, a power controller, and a phase-locked loop for grid synchronization. We outline a structure-preserving reduced-order inverter model for the setting where the parallel inverters are each designed such that the filter components and controller gains scale linearly with the power rating. By structure preserving, we mean that the reduced-order three-phase inverter model is also composed of an LCL filter, a power controller, current controller, and PLL. That is, we show that the system of parallel inverters can be modeled exactly as one aggregated inverter unit and this equivalent model has the same number of dynamical states as an individual inverter in the paralleled system. Numerical simulations validate the reduced-order models.
Original languageAmerican English
Number of pages9
StatePublished - 2017
EventIEEE Workshop on Control and Modeling for Power Electronics - Stanford, California
Duration: 9 Jul 201712 Jul 2017


ConferenceIEEE Workshop on Control and Modeling for Power Electronics
CityStanford, California

Bibliographical note

See NREL/CP-5D00-70295 for paper as published in IEEE proceedings

NREL Publication Number

  • NREL/CP-5D00-68202


  • dynamic states
  • grid connected inverters
  • interfaces
  • inverter
  • LCL
  • system load


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