Shunt active power filter voltage sensorless method using a PR controller for unbalanced grid conditions

Abstract

Unbalanced issues and power quality problems can be handled using shunt active power filters (APFs). Under weak grid conditions and unbalanced grid impedance, the unbalanced three-phase load leads to unbalanced grid currents and point-of-common-coupling voltages. As a result, there will be a significant fluctuation in the real and reactive power of the grid. Several shunt APF control methods were used to solve unbalanced problems. Both voltages and currents measurements are required in the control method. Proposed in this article is a new voltage sensorless control method of shunt APF by using current measurements only. The reference current of the controller was determined from the positive-sequence component of the measured load currents. The APF was controlled by a PR controller. The proposed approach can eliminate fluctuation in the real and reactive power and balance point-of-common-coupling voltages and grid currents. Simulation and hardware experiments were used to verify the proposed method’s performance.

Keywords

• Proportional-resonant controller
• Shunt active power filter
• Voltage sensorless control
• Unbalanced grid conditions
• Three-phase inverter
• dSPACE DS1202