This paper proposes three dynamic voltage restorer (DVR) topologies. Such configurations are able to compensate voltage sags/swells in three-phase four-wire (3P4W) systems under balanced and unbalanced conditions. The proposed systems in this work use two independent dc-links. The complete control system, including the PWM technique, is developed and comparisons between the proposed configurations and a conventional one are performed. Simulation and experimental results are provided to validate the theoretical approach.
Fig. 1 Typical DVR location in a 3P4W power distribution system
EXPECTED SIMULATION RESULTS:
Fig. 2. Simulation results. Injected voltages by the DVR considering conventional 3HB topology and proposed configurations with equal dc-link voltages (vCa=vCb ! dc-link ratio 1:1) and different dc-link voltages (vCa 6= vCb ! dc-link ratios 1:2 and 1:3).
Fig. 3 Simulation results. Dynamic system operation under 30% single-phase sag in time domain. (a) Grid voltages. (b) Injected voltages by DVR. (c) Load voltages.
Fig. 4. Simulation results. Dynamic system operation under 30% two-phase sag in time domain. (a) Grid voltages. (b) Injected voltages by DVR. (c) Load voltages.
Fig. 5. Simulation results. Dynamic system operation under 30% three-phase sag in time domain. (a) Grid voltages. (b) Injected voltages by DVR. (c) Load voltages.
In this paper three four-wire dynamic voltage restorers (DVRs) have been presented. The studied configurations in this work are based on the concept of open-end winding. Simulated and experimental results presented show that the proposed DVRs are feasible and suitable for power distribution system with YY transformers with neutrals grounded.
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