"This dissertation proposes new control algorithms dedicated towards improving the reliability, computational burden and stability in grid-connected and stand-alone based power electronic converter systems applicable for ac microgrids.
Two voltage sensorless control architectures, one for stand-alone applications and the other for grid-connected application are established in this thesis. The output voltage of a standalone single-phase inverter is controlled directly by controlling the output filter capacitor current without using a dedicated output voltage sensor. A method to estimate the output filter capacitance is also presented. For the grid connected converter, a novel closed loop estimation is presented to estimate the grid voltage. In addition to the estimation of the grid voltage, the proposed method also generates the unit vectors and frequency information similar to a conventional phase-locked loop structure. The voltage sensorless algorithm is then extended to LCL filter based grid connected converters thereby proposing a new indirect method of controlling the grid current.
Furthermore, addressing the stability issues in current-controlled grid tied converters, this dissertation also analyzes the power angle synchronization control of grid-tied bidirectional converters for low voltage grids. The power flow equations for the low voltage grid are analyzed and compensators are designed to ensure the decoupled control of active and reactive power. It is demonstrated that the proposed compensators are immune to grid fluctuations and ensure stable operation controlling the desired power flow to and from the grid.
Detailed plant modeling, controller design, simulation and experimental results are presented for all of the proposed schemes"--Abstract, page iv.
Kimball, Jonathan W.
Electrical and Computer Engineering
Ph. D. in Electrical Engineering
Missouri University of Science and Technology
Journal article titles appearing in thesis/dissertation
- Control of a single-phase standalone inverter without an output voltage sensor
- Grid voltage estimation and current control of singlephase grid-connected converter without grid voltage sensor
- Indirect grid current control of an LCL filter based grid connected converter
- Model reference adaptive control based estimation of equivalent resistance and reactance in grid-connected inverters
- Power-angle synchronization with fault ride-through capability for low voltage grids
xviii, 179 pages
© 2017 Subhajyoti Mukherjee, All rights reserved.
Dissertation - Open Access
Electronic OCLC #
Mukherjee, Subhajyoti, "Advanced control architectures for grid connected and standalone converter systems" (2017). Doctoral Dissertations. 2627.