Sequence analysis based DSP controller for Dynamic Voltage Restorer (DVR)

The paper examines the behaviour of a dynamic voltage restorer (DVR) under balanced/unbalanced supply voltage sag condition, and restricted DVR injection capability (e.g. limited to 50% of the supply voltage injection). Sequence components of the supply voltage are extracted to generate the reference injected voltage for the DVR. The control determines the maximum possible positive sequence injection within the capacity of the compensator to achieve balanced voltage conditions at the load terminals. The control is verified through simulation and experimentation. The control algorithm has been implemented in a TI320F2812 fixed point DSP and the effectiveness of the controller is verified in a three-phase, 10kVA DVR laboratory prototype. In a three-phase, 240 V system, balanced sag and sag with magnitude and phase unbalance have been created, which is successfully compensated by the DVR with the proposed controller.