Flexible Active Compensator Control for Variable Compensation Objectives

In this paper, a new approach is proposed to increase the flexibility of the reference current generation for active compensators. Although compensating all useless components of the current is ideal, it is sometimes desirable to target a subset of the possible components of the current due to power electronic converter power, switching speed limitations, etc. Furthermore, power quality objectives may vary over time. The proposed strategy utilizes a novel reference signal generator to provide online flexibility with respect to the compensation objectives. The reference signal generator utilizes a computationally efficient moving-window discrete Fourier transform along with an orthogonal decomposition of the current instead of the filters typically used to extract the desired components of the current. Each orthogonal component of the current can be adjusted independently in any percentage, thus providing the selective current compensation. The proposed reference signal generator also allows for easy extrapolation of the measured current, effectively canceling the delay inherent in the digital current control loop. Cancellation of the delay allows for the elimination of the spikes that typically occur due to poor tracking of fast slope transitions of the current reference. The advantages of the proposed control architecture have been verified by an experimental prototype.