Online application of SHEM to grid-connected inverters with variable DC link voltage by particle swarm optimization /

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2014
Güvengir, Umut
In this thesis, online selective harmonic elimination method (SHEM) has been applied to a voltage source converter (VSC) based grid-connected three-phase two-level inverter with variable DC link input voltage eliminating 5th, 7th, 11th, 13th, 17th, and 19th harmonics in the output voltage. The switching angles of SHEM are given by a set of nonlinear transcendental equations. Particle swarm optimization (PSO) algorithm is used for the solution of this equation set, and this algorithm is implemented in the field-programmable gate array (FPGA) for a fast and online calculation of switching angles in real time without using a lookup table. FPGA is used as the main and sole controller in the implemented voltage source inverter (VSI) to provide gating signals for IGBTs. In applications where input DC link voltage varies in a wide range, usage of lookup table for switching angle sets might be disadvantageous due to discretization of modulation index values, large lookup table storage, and infeasible region of solution space, which are investigated in detail in the thesis, with explanatory examples. The effects of PSO algorithm parameters on searching performance are also elaborated. FPGA implementation of PSO algorithm for solution of SHEM equation sets is described in detail. A 1.6 kVA, 380 V, three-phase VSI is successfully implemented and tested in the laboratory. Hardware co-simulation, computer simulation, and experimental results have shown that SHEM can be successfully applied online for the control of grid-connected inverters.

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Citation Formats
U. Güvengir, “Online application of SHEM to grid-connected inverters with variable DC link voltage by particle swarm optimization /,” M.S. - Master of Science, Middle East Technical University, 2014.