University of Illinois Urbana-Champaign

Secondary voltage and frequency control for dispatchable virtual oscillator controlled inverters

Roberts, T.G.

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https://hdl.handle.net/2142/115803

Description

Title
Secondary voltage and frequency control for dispatchable virtual oscillator controlled inverters
Author(s)
Roberts, T.G.
Issue Date
2022-04-29
Director of Research (if dissertation) or Advisor (if thesis)
Dominguez-Garcia, Alejandro D
Department of Study
Electrical & Computer Eng
Discipline
Electrical & Computer Engr
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
M.S.
Degree Level
Thesis
Keyword(s)
  • Grid Forming Inverter
  • Dispatchable virtual oscillator control
  • dvoc
  • secondary frequency control
  • secondary voltage control
  • power systems
Abstract
With the introduction of more distributed energy resources (DERs) on the grid, there is also a decrease in the amount of rotating inertia that can be relied upon to keep the grid frequency and voltage stable. Grid following inverters (GFLs) connect renewable resources to the grid but do not have capabilities to control their output frequency and voltage, and are instead susceptible to any grid disturbances. Grid forming inverters (GFM) in contrast, are inverters that can help keep voltage and frequency stable; even in systems with high percentages of renewables or microgrids that are fully renewable based. In this thesis we examine three types of GFMs, droop controlled, virtual synchronous machine (VSM) controlled, and dispatchable virtual oscillator controlled (dVOC), in both their steady state and dynamic responses. The steady state responses are examined in order to determine how nonlinearities in the dVOC-based inverters compare to the linear behavior of droop and VSM control. Then, for the dynamic simulations, power flow is first be solved using modified versions of the distributed slack bus Newton-Raphson (NR) power flow problem to find initial conditions. Followed by both primary controlled open-loop simulations with a three bus microgrid, and secondary controlled closed-loop simulations on the same system. Finally, we present how the systems react to disturbances, and then outline a plan for further testing.
Graduation Semester
2022-05
Type of Resource
Thesis
Copyright and License Information
Copyright 2022 T.G. Roberts

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