Abstract—This
paper investigates the suitability of selective harmonic elimination (SHE) for
low-loss multimegawatt gridconnected photovoltaic (PV) inverters. The proposed
system is able to meet utilities regulations, IEEE and IEC standards. In an
attempt to substantiate the potential superiority of SHE over carrier-based or
space-vector pulsewidth modulation (PWM), this paper demonstrates that SHE may
allow grid-connected PV inverters to be controlled using a switching frequency
of less than 1 kHz, while the inverter is still able to provide necessary
operation features such as independent control of active and reactive powers
and operation control simplicity. For system validation, experimental results
with SHE are compared to the case when the inverter is controlled using
third-harmonic injection PWM, with a 2-kHz switching frequency. Furthermore,
the paper proposes a new implementation technique for SHE that utilizes the
third harmonics to spread the switching angles over 90◦
instead of being located in a narrow range as generated when using
conventional techniques, along with increases in modulation index. The
advantages of the proposed technique include simplicity in implementation and
flexibility in PWM waveforms. Simulation and experimentation demonstrate
agreement, which validates the practicability of the proposed system.
(Index
Terms—Grid-connected photovoltaic inverters, highpower medium-voltage
inverters, pulsewidth modulations (PWMs), switching losses.)
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