Fig 1.
Topology of the three-level active power filter with an LCL filetr.
Fig 2.
The single-phase equivalent circuit diagram of APF.
Fig 3.
Bode diagram of the QPR controller.
Fig 4.
The Bode diagram when changes.
Fig 5.
Schematic diagram of the QPR control.
Fig 6.
The structure diagram of the repetitive control.
Fig 7.
Bode diagram of the LCL filter.
Fig 8.
Nyquist curve of the .
Fig 9.
The structure diagram of repetitive QPR control.
Fig 10.
The structure diagram of first-order LADRC control.
Fig 11.
The structure diagram of repetitive QPR-LADRC control.
Fig 12.
Control strategy of the voltage outer loop.
Fig 13.
RTDS real-time simulation hardware platform.
Table 1.
Simulation parameters of the APF system.
Fig 14.
Steady-state current tracking waveforms of the three control strategies.
Fig 15.
Steady-state voltage and current waveforms of the three control strategies.
Fig 16.
The current waveforms of the three control strategies during APF start-up.
Fig 17.
The DC-side voltage waveforms of the three control strategies during APF start-up.
Fig 18.
The current waveforms of the three control strategies during load mutation.
Fig 19.
The DC-side voltage waveforms of the three control strategies during load mutation.
Table 2.
Comparison of harmonic current THD before and after filtering.
Table 3.
Comparison of the 5th, 7th and 11th harmonic current THD before and after filtering.