Predictive Control of Three Phase AC/DC Converters

88 CHAPTER 5. INVESTIGATIONS OF CONTROL METHODS PERFORMANCE
u La
u Lb
u Lc
(a)
VF-CSF-P-DPC
i La
(b)
u La
U DC
i La
P ref
Figure 5.18: Operation under two phase voltage sag: (a) line voltages u La , u Lb ,
u Lc (100 V/div), line current i La (10 A/div), (b) line voltage u La (200 V/div),
U DC voltage (100 V/div), line current i La (10 A/div), referenced active power
P ref (1 kW/div)
(see Fig. 4.11), which increases line current value. For both controls, the operational
limit is set to the maximum allowable converter input current. When
the current limit is exceeded, the converter is being shut down. The converter
operates in similar way in case of two phase voltage sag.
Figure 5.17 shows line current T HD factor in presence of single and two phase
voltage sags. In both cases, the VF-CSF-P-DPC is more robust to disturbances,
than control with direct line voltage measurements.