Environmental Engineering Reference
In-Depth Information
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(a) Frequency tracking
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E
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(b) Amplitude tracking
Figure 23.6
Frequency and amplitude tracking for a distorted noisy signal with a variable frequency:
Experimental results with the SLL (left column) and with the SOGI-PLL (right column)
produce the correct frequency, all with noticeable overshoot. Apparently, the SLL outperforms
the SOGI-PLL significantly.
23.8.2 With a Noisy Distorted Signal having a Variable Frequency
The voltage signal used in Section 23.7.1 was generated and sent out via a DAC channel as
the voltage signal
. Again, the experiment was carried out for the SLL and the SOGI-PLL
with the results shown in Figure 23.6. The experimental results matched the simulation results
shown in Figure 23.3. The SLL tracked the frequency and the amplitude very well; the SOGI-
PLL was able to track the frequency and the amplitude but with much bigger ripples. The
experimental results when the frequency changed from 40 to 50 Hz are shown in Figure 23.7.
The SLL tracked the frequency quickly. The SOGI-PLL tracked the frequency well but there
were noticeable variations in the frequency after the jump.
v
23.8.3 With a Noisy Distorted Square Wave
The voltage signal used in Section 23.7.2 was generated and sent out via a DAC channel as
the voltage signal. Again, the experiment was carried out for the SLL and the SOGI-PLL. The
results are shown in Figure 23.8. The experimental results matched with the simulation results.
The SLL was able to track the phase, frequency and amplitude but the SOGI-PLL cannot track
the amplitude. The voltage recovered by the SLL is very clean but the voltage recovered by
the SOGI-PLL contains significant harmonics.
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