Fast Determination of Distribution-Connected PV Impacts Using a Variable-Time-Step Quasi-Static Time-Series Approach

Research output: Contribution to conferencePaper


The increasing deployment of distribution-connected photovoltaic (DPV) systems requires utilities to complete ever more complex interconnection studies. Relatively simple interconnection study methods worked well for low penetrations of photovoltaic systems, but more complicated quasistatic time-series (QSTS) analysis is required to make better interconnection decisions as DPV penetration levels increase. Tools and methods must be developed to support this type of complex analysis to enable efficient completion of PV impact studies. This paper presents a variable-time-step solver for QSTS analysis that significantly shortens the computational time and effort to complete a detailed analysis of the operation of a distribution circuit with many DPV systems. Specifically, it demonstrates that the proposed variable-time-step solver can reduce the required computational time by as much as 84% without introducing any important errors to metrics, such as the number of voltage regulator tap operations and highest and lowest voltage occurring on the distribution circuit during a 1-yr simulation period. Further improvement in computational speed is possible with the introduction of only modest errors in these metrics, such as a 91% reduction with less than 5% error when predicting voltage regulator operations. Furthermore, an alternate variable time-step method is also shown to perform adequately and shows promise of even greater reductions in simulation runtime.
Original languageAmerican English
Number of pages6
StatePublished - 2018
Event2017 IEEE 44th Photovoltaic Specialist Conference (PVSC) - Washington, D.C.
Duration: 25 Jun 201730 Jun 2017


Conference2017 IEEE 44th Photovoltaic Specialist Conference (PVSC)
CityWashington, D.C.

Bibliographical note

See NREL/CP-5D00-67769 for preprint

NREL Publication Number

  • NREL/CP-5D00-73964


  • distribution system modeling
  • PV grid integration
  • QSTS
  • time-series analysis
  • variable time-step


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